Category Archives: Sony A1

Full Frame, Sony A1, Underwater Photography, UNDERWATER VIDEO, Wet lenses, wide angle

Nauticam WWL-1 on Sony Full Frame what to expect

March 11, 2023 interceptor121 1 Comment

It has been almost 9 years since my first review of the Nauticam WWL-1 and five years ago I revisited this lens on micro four thirds.

Since the very first release I was told by Nauticam that the WWL-1 had been tested on Sony full frame with the 28mm f/2 lens and since then more lenses have been added to the compatibility list and the WWL-1 itself has had a redesign called WWL-1B, this lens has an integrated float collar and I do not know if there is any difference in the optics but I assume there is none.

Nauticam has since released a number of other water contact optics with dry mount and today you have a choice of at least 3 flavours for your Sony full frame camera that provide the 130 degrees diagonal field of view.

Model	Price (€)	Weight (kg)	Diameter (mm)	Depth (mm)	Max Filter size (mm)
WWL-1	1424	1.35	156	97	52
WACP-C	2930	2.24	170	145.5	72
WACP-1	4604	3.90	194	176	82

Summary Table Nauticam 0.36x Water Contact Optics

The three lenses provide the same field of view but they are different in size and mount. A useful way to see is that as the lens physical size grows you require a larger underwater optic.

The Sony E-Mount is still the only full frame format compatible with the WWL-1 in virtue of some really small and compact lenses. As you can see from the table above the WWL-1 rear element is large enough for 28mm lenses that have a maximum filter size of 52mm.

Two E-mount full frame lenses the 28/2mm prime and the 28-60mm zoom are compatible with the WWL-1.

As you move towards the WACP-C you can also use the 28-70mm lens which is one of the worst kit lenses on the market but will give you a longer tele end and finally the WACP-1 gives access to the Tamron 28-75mm and Sigma 24-70mm two lenses that have much higher quality than the smaller Sony lenses but have some restriction in terms of zoom range.

Underwater Performance Context

There are quite long discussions about which water contact optic to get for your Sony full frame once you have the 28-60mm zoom and some comparison in terms of sharpness.

In simple terms you can think of the following equation:

Underwater Performance = Land performance X Port Factor

Port Factor is always less than 1 which means a lens will never do in water as well than it does on land. Looking at my analysis of the 28-60mm corroborated by other test you know before buying any water contact lens that the lens has its own limitations and no matter how good is the port performance will only go down. However this may still be a better option compared to a standard dome port.

I do not have access (yet) to the other two water contact optics however I have a good idea of how the WWL-1 perform and how the Sony 28-60mm performs topside. If you want a refresh look at this article.

To understand how a water contact optic works you can go back all the way to the Inon UWL-100.

The idea of this lens designed for compact cameras is to demagnify the camera master lens to enlarge the field of view. You could then get an optional dome that will enable the lens to expand the underwater field of view from 100 to 131 degrees.

Back in 2015 I compared the Inon UWL-H100 with dome with the WWL-1 and concluded that the WWL-1 was giving better results when used on the same camera. It is now time to see if the WWL-1 can be used also on a full frame system.

Sony A1 WWL-1 Rig

The WWL-1 requires the flat port 45 to be used on a Sony full frame underwater housing. The lens will be attached using the same bayonet adapter that has been available for several years now.

I have removed the focus knob from the port as I found it inconvenient. The focus knob may be useful with the flat port but for the WWL-1 that is afocal is definitely not required.

Once you add the flat port the overall length is very much the same of the WACP-C but this will require an extension ring resulting in overall 30mm additional length.

Overall the rig is very similar in weight to the Canon 8-15mm with the Acrylic Dome Port 5.5″.

Pool Tests

With the rig assembled I went for a pool session with the objective of finding out what was the overall performance of the system.

What follows are a series of test shots of divers.

In general I found the lens to be sharper in the centre at f/8 but closing down to f/11 was required if there was something in the corners.

Edge Sharpness

I was intrigued by a number of discussions on edge sharpness and after several exchanges with Shane Smith he was clear that the lens needs to be stopped down to f/11 for best results.

After the session in the pool I would agree with Shane however I was curious if this was an issue of the WWL-1 or the 28-60mm lens itself.

This image quite simple has something at the edges and has focus in the centre at f/8.

You will notice that the part of the frame closer to the camera is fairly blurry.

So I did another experiment placing the slate on the edge.

The edges were quite fuzzy. I wanted to exclude this was an issue of depth of field so I focussed right on the corner.

This is the resulting image and is still soft on the edge.

I then took the same shot at f/11 with focus on centre.

The image at the edges is better. Then moved the slate to the edge.

The image improved overall regardless of the focus point indicating this is not a depth of field issue but some other defect of the lens, most likely as the lens meridional and sagittal resolution are different we have an example of astigmatism.

The sharpness improves closing down the lens regardless of where the lens is focussing consistent to the MTF charts.

Looking back at land test shots we can see something very similar.

In conclusion it is not about the WWL-1 but about the lens itself.

Comparison to Rectilinear lenses

While the WWL-1 can offer a diagonal feld of view of 130 degrees the image is distorted and the lens can only offer 107 degrees horizontally and 70 vertically. Is like saying that the horizontal field of view is similar to a 13mm rectilinear lens while the vertical is is more like 17mm. A fair comparison is probably a 14mm rectilinear lens but as the WWL-1 is a fisheye like optic a direct comparison is not entirely possible. In my opinion as the image is distorted is more appropriate to compare the WWL-1 with a fisheye with teleconverter and when I look at what the canon 8-15mm with kenko 1.4 tc can produce for me the results are very similar, I would say the Canon has in fact an edge however the field of view are not comparable except when the WWL-1 is at the widest and the canon with the tc at the maximum zoom. I would go as far as to say that the canon + TC at f/8 is as good as the WWL-1 at f/11.

Conclusion

If you have the WWL-1 from your previous rig it makes absolutely sense to get the Sony 28-60mm and flat port. This combination will give you decent (but not sensational) shots and work very well for 4K video at reduced resolution. I do not believe that this lens can resolve the full 50 or 60 megapixels of the A1 or A7R4 or A7R5 even topside.

If you are starting from scratch I would recommend to think careful at your intended use case. If you want angles wider than 130 degrees and already have the Canon 8-15mm you may want to check the kenko telecovenverter before you buy a new port as all you need is a 20mm extension ring and a zoom gear.

If you really like the field of view range of 69-130 degrees you need to consider which water contact optic you need.

I am still looking for a test WACP-C but until then my general guidance would be to consider simply if you prefer a dry or wet mount.

A dry mount has the benefit of being ready to go as you hit the water, without the need to remove bubbles between the wet lens and the port. As photographer a dry mount may be the best way forward.

If you intend to use your camera for video and insert filters between the lens and the flat port or you require the lens to be removed in water then go for the WWL-1.

Rigorous comparisons between WACP-C and WWL-1 are not yet available but the first indications are that the difference in image quality is very small therefore I would not loose my sleep there and look more at overall ergonomics.

The final consideration is should you get the WACP-1 instead? Based on my assessment of the Sony 28-60mm I would think this is not particularly wise even if this choice is very popular. Personally I always believe that the master lens needs to be good enough to justify the cost of the water optic so I would like to see how the Tamron 28-75mm performs however no test images are available so I am not in a position to conclude.

In my case having seen what the Sony 28-60mm lens can do I am not planning to invest in a WACP-C but I would be very interested in testing one.

The WWL-1 gets my approval also on full frame but it is not going to give me the same resolution than the Canon 8-15mm or the Sony 90mm macro will give. I look forward to testing some rectilinear lenses to see how those compare and this will happen in a week from now so stay tuned.

Costs to get one for your Sony full frame excluding lens:

WWL-1B €1,424
Bayonet adapter €102
N100 45 flat port €494

Total €2,020 vs WACP-C + N100 Extension Ring 30 €3,333

Canon EF lens, Dome Port, Fisheye lens, Full Frame, Sony A1, Underwater Photography, wide angle

Canon 8-15mm with 4.33″ Acrylic Dome for Sony A1

March 4, 2023 interceptor121 19 Comments

Following from a previous article about not increasing bulk I have considered a few options for the Canon 8-15mm fisheye.

The 8-15mm is not a small lens and due to the different flange distance between Canon EF mount for DSLR (44mm) and Sony E-Mount (18mm) we have a chunky 35.5mm N100 to N120 adapter port that makes the whole set up not that compact.

Dome Options 140mm vs 4.33″

The Nauticam port chart recommends the 140mm glass fisheye dome for the 8.15mm, this port is 69mm radius and is made with anti reflective optical glass and weights 630 grams.

There is another dome from Nauticam the 4.33″ acrylic but this does not feature on the port chart for the Canon 8-15mm.

I did some calculations and this dome should require the same extension so I ordered one conscious that this would be lighter but not necessarily increase the underwater lift due to a reduced volume.

Although there is a difference of 362 grams the smaller volume will result in less buoyancy 348g lift vs 688g lift for the 140mm so overall the additional buoyancy is only 22 grams.

The primary benefit of this smaller dome is that it gets you closer this in turn means that things will look bigger and as consequence depth of field will drop. Depth of field depends on magnification and as you will get closer it will drop compared to other domes. So larger domes have more depth of field not because they are larger when you are at close range but simply because your camera focal plane is standing further back.

To give an idea this is a little miniature shot with the 140mm dome with the target touching the glass port.

This is the same target with the 4.33″ dome.

Side by side shows the difference in magnification.

If we look at the same detail we can see that the 140mm dome image detail is less blurred.

We are on land here there is no water involved and the 140mm image is sharper at the edge simply because it is smaller.

As depth of field must be compared at equal magnification we can also bust another myth of larger domes vs smaller domes there is no increased depth of field you are just standing further back if you compared the front of the port instead of the focal plane.

Building the Rig

The extension required is still 30mm as for the 140mm dome,

The overall size of this dome means it is flush with the extension ring.

Port details the lens hood must be removed

This is the overall rig with the amount of flotation in this image it is around 600 grams negative in fresh water.

Now that we know what to expect is time to get in the pool and take some shots. I got some miniature aquarium fixtures to simulate a close focus wide angle situation.

Pool Session

Once in water I set up my artificial reef and got shooting.

I was at the point of touching the props so I had to stand back a little. As expected the issue is depth of field.

Shots at f/11

For starter we try to get as close as possible and focus in line with the chick.

Due to the extreme magnification the front details are quite soft. So from here I start moving backwards a little.

Still focussed on the chick the sharpness improves due to reduced magnification this is a simulation of a larger dome.

There still is severe blurring of the front detail at f/11. However due to the increased depth of field that the dome brings behind the focus point the rest looks pretty good.

Focussing on the middle of the frame at f/11 results in blurry details for the features in the front of the frame but much less blurry than before and the chick is still relatively sharp.

Focussing on the pink reef detail results in a better overall result in a counterintuitive way.

Shots at f/16

Stopping down the lens results in increased depth of field so more of the image is in focus however the overall sharpness drops. This is a good place to be if you don’t want to be too sophisticated with the choice of focus point and you are close.

You can get closer but the front detail is still a bit soft but acceptable.

If you move your focus point a bit further in front the situation improves.

At this point I decided to get into the picture with a white balance slate.

Although the front is quite blurry due to the extreme close range the result is acceptable for the non pixel peeper.

Shots at f/22

We are here hitting diffraction limit and the image looses sharpness but we are after depth of field so be it.

Now the depth of field is there although the detail in the centre is less sharp.

Moving the focus point makes the image a bit better.

Time to insert the diver in the frame.

Overall ok not amazing consider the dome is on the parts.

Conclusion

The small acrylic dome does quite well at close range, the limitations come from the depth of field and not from the water and the dome increases the depth of field behind the focus point. This is something that you can use to your advantage if you remember when you are in open water.

For shots that are further away you can shoot at f/11 and get excellent IQ there is no need to stop down further to improve the edges. Consider however that f/8 may be just too wide on full frame and introduce additional aberrations regardless of depth of field.

Some numbers:

Nauticam 140mm Glass dome: £911

Nauticam 4.33″ Acrylic dome: £550

Price difference £361 or 40% however bear in mind that the primary benefit of the glass dome is to resist reflections and ghosting due to the coating and the fact you can keep the 8-15mm hood on.

Canon EF lens, Fisheye lens, Full Frame, Sony A1, Underwater Photography, wide angle

Fisheye Lenses for Underwater myths vs reality

February 26, 2023 interceptor121 Leave a comment

There are several myths surrounding fisheye lenses when it comes to underwater use.

A quick tour to underwater photography guide usually a good source of information.

Myth Busting

Properties of fisheye lens as per UWPG:

They usually focus very close

They are small and light

When shooting ultra-wide angle, you benefit from a large depth of field

You can get very close to large subjects, maximizing color and sharpness

They perform well behind dome ports with good corner sharpness, and they don’t need a diopter

You usually need at least 2 strobes with good angle of coverage to properly light the entire area.

Some of the above statements are correct in absolute, some are correct but not specific to fisheye lenses and some are just incorrect.

Fisheye lenses usually focus very close -> true for the most recent fisheye lenses, not true for some older models

They are small and light -> Not true. Canon 8-15mm and Nikon 8/15mm are fairly chunky lenses with lots of glass

When shooting ultra-wide angle, you benefit from a large depth of field -> not a property of the fisheye lens but of the focal lens. In fact due to the extreme field of view Fisheye lenses have issues of depth of field.

This is a tea towel shot with a rectilinear lens. Note how sharp the target is at f/5.6

This is the same target at the same distance with the Canon 8-15mm at f/5.6 note how the edges are blurry and the blur starts very near centre.

You need to stop down the lens to f/16 to start getting coverage for the edges.

You can get very close to large subjects, maximizing color and sharpness -> This is a consequence of close working distance and wide field of view however sharpness is another story

As we have seen before fisheye shots at close distance are generally not that sharp especially at the edges.

They perform well behind dome ports with good corner sharpness, and they don’t need a diopter This happens to be true in practice and it is a major benefit for the underwater shooter

We will dive in detail in this topic.

You usually need at least 2 strobes with good angle of coverage to properly light the entire area. Fisheye lenses cover an aspect ratio wider than the format aspect ratio and result in limited vertical angle of coverage. Fisheye lenses are ideal for two strobes except the very far edges.

Canon 8-15mm specifications.

Horizontal field of view: 142 degrees

Vertical field of view: 91 degrees

A barrel gives an idea of the fisheye lens distortion

Let’s ignore the edges and assume we are a one meter.

Horizontal field of view 2*tan(71)=5.8 meters

Vertical field of view 2*tan(45.5)=2.03

Aspect Ratio = 2.85:1

The issue with fisheye lenses is that the frame is really very wide much wider than it is tall. This means some of the edges on the horizontal axis will be normally dark unless you are very very close.

Fisheye lenses and Dome Ports

A dome is simply a lens with a single element that has the property to retain the air field of view of a lens.

A dome is a lens with a lot of field of curvature simply because it is bent.

Using the dome port visualiser we can see that the effect of a dome is to bring the image closer to where it really is.

The net effect of a dome port is to increase the depth of field as infinity focus is reached much sooner.

A dome port has several side effects the main ones are:

Spherical aberration
Field of curvature

A fisheye lens works opposite to a dome. The centre of the frame is closer to the lens the edges are further away.

Domes, field of curvature and Fisheye lenses

In order to understant how the barrel distortion works in combination with a dome port and a fisheye lens we can build a small simulation in a light box where the edges of the frame are closer than a flat target.

We can see that despite the edges are quite blurry this image is actually better than our flat target.

At f/11 the image is not perfect but we can see that most details off centre are not looking bad at all.

it is definitely blurry but not as bad as the tea towel as if the way the element are laid out improves the image in the corners.

And this is exactly the point: the items as laid out emulating the curvature of a dome improve the fisheye lens performance.

By f/16 the image is almost all sharp.

One trick is not to focus in the back of the frame but find a middle point this means we can find additional depth of field in front of the target.

Let’s see how this goes. at f/11 we already get some better results.

At f/16 we get some additional improvement but is not as major as the original f/16

Looking at the other areas there are some minor improvements but generally less as we close down the aperture.

In conclusion the layout of the image elements helps the fisheye lens to achieve better image quality this can be futher improve focussing off centre however closing down the aperture results in the best results regardless.

In short we can improve an image at f/11 by shooting off centre in a strategic point to improve depth of field but ultimately aperture plays a bigger role in improving performance of the fisheye lens.

A similar reasoning can be applied to dome size vs closing down the aperture.

We can plot a scenario in the dome simulator tool.

In the starting example our aperture is 4cm to similate our 15mm lens at f/4.

We now reduce the aperture to 2cm which is more or less f/8

And finally to 1cm which is more of less f/14. In reality this is mm not cm but should make you understand that aperture matters more than anything else.

What we can see is that by reducing the aperture the light rays passing through the dome converge and this means stray light is reduced and as consequence spherical aberrations are decreased.

Let’s now introduce dome size which is the equivalent of depth of field in the mix in our light box shooting off centre.

We can see that with a double size dome the converging effect on the light rays is not as significant as the aperture is already small, but nonetheless is present. This is consistent with our f/11 off centre use case.

Finally at aperture completely closed.

Although virtual distance has increased significantly the effect of the large dome on the stray rays is not significant here aperture rules.

What does all of the above mean?

I realise this was a bit geeky.

To summarise a dome has two issues one is spherical aberration for the very shape of the dome. This is mostly cured by closing down the aperture. Dome size has limited effect here unless you shoot wide open and with apertures from f/14 we can see that large dome vs small dome does not really matter.

However when it comes to field of curvature large dome helps the situation but because fisheye lens have barrel distortion and this has a counter effect to dome shape curvature therefore dome size matters much less to a fisheye lens than it would to a rectilinear lens.

Some additional insight in this post. And the summary finding here.

The takeaway message is this: stopping down the aperture improves field curvature and astigmatism somewhat, improves coma a lot, and improves spherical aberration most of all. The sum total of these effects changes our ‘area of best focus’, which is what we photographers really mean when we say ‘field curvature’.

We could paraphrase this by saying:

A dome port increases depth of field and a fisheye lens, due to barrel distortion, benefits from a dome port. Optical aberrations introduced by the dome are mostly addressed by stopping down the aperture. The size of the dome port does not matter too much when using a fisheye lens and the benefit on aberrations of a much larger size dome is likely to be minimal when we look at that simulator. Focussing appropriately mitigates residual issues of field of curvature of the dome for the fisheye lens.

Underwater proof of concept

I took my Sony A1 with a Canon 8-15mm first and then with a WWL-1 that behaves very much like a fisheye lens.

Let’s have a look at some images shot with Nauticam 140mm dome.

The image above sees two buddies in the frame almost flat with their fins going back in the frame however the result is much better than the lightbox example as result of distance and dome port increasing field of view and adding curvature to bring the fins in.

This however does not resolve all issues if you focus near like in this example focussed on the eye of the croc

Here the eye is close resulting in the tail being blurred this is an effect of close distance and lack of depth of field despite the dome.

More interesting the nose is even more blurred as the dome brings that even close and blurs away due to field of curvature as the focus point is behind.

In this other example instead of focussing on the eye the focus goes mid frame so the fins are still in decent shape even if deep in the frame at f/8.

In order to prove the concept even more I took some props underwater.

First let’s have a look a shot at f/8 with the WWL-1.

As we can see the image is not too bad even in the close area but it is definitely better at f/11

What happens if we position the target off centre?

Contrary to our topside example the situation does not improve by focussing on the edge to further prove the issue here is NOT depth of field.

Here a detail crop the image is still fuzzy despite then focus is right on the spot. Depth of field is not the issue.

And finally we close down the aperture to f/11.

Crop at 100%

So here we can see that the underwater interface provides already for the depth of field but moving the focus at the edges does not have such a good effect.

Why? Because this is likely to do with aberrations of the lens itself as shown in my previous post on the Sony 28-60mm.

The combined 28mm with WWL-1 at f/8 means 20/8-2.5 mm aperture when stopped down to f/11 this becomes small enough to cure aberrations (less than 1cm with reduced field of view is sufficient).

For the same reason ASPC and MFT will be able to shoot at wider aperture not because of depth of field but due to smaller lens aperture.

15mm fisheye at f/14 –> 1.07mm physical aperture

8mm MFT fisheye at f/8 –> 1mm physical aperture

Again it is not the depth of field but the aperture size to cure most aberrations.

Conclusion

All Nauticam port chart recommend the 140mm dome and not larger domes. This is aligned with the theory behind this post that dome size ultimately matters but not as much as stopping down the lens and that fisheye are naturally helped by dome port geometry.

This conclusion also extends to water contact optics which are composed by a fisheye like demagnifier and an integrated dome port.

As long as the rear element of the lens is big enough the increased size of the lens does not result in proportional improvement of performance.

To support the empirical evidence of this article you can read this review of the 140mm dome by Alex Mustard.

By coincidence Alex recommends shooting at f/14 or f/16 which means a physical aperture of 1mm which cures all sorts of aberrations.

Considering that the benefit of a much larger dome may be as small as 1/2 to 2/3 aperture stops you may consider going the opposite way and get a very small dome which will result in additional spherical aberration and will need to be stopped down more when shooting very close.

If you use the Nauticam system there are only two ports that are a full emisphere and therefore able to contain a fisheye lens field of view:

140mm optical glass fisheye port
4.33″ acrylic dome port

I happen to own both those ports and in a future article will compare and contrast the two. I will also revisit the topic of dome ports and rectilinear lenses which is obviously different from fisheye lenses.

ambient light, Full frame, Nikkor, Sony A1, UNDERWATER VIDEO, wide angle

Nikkor UW15 on Sony Mirrorless for photography – Worth it?

February 19, 2023 interceptor121 Leave a comment

Nauticam makes some really interesting adapters and ports for Sony cameras, one of them allows you to use vintage Nikkor lenses on full frame mirrorless cameras.

I decided to source the UW15 as I am planning to use it for video after seeing the results on the movie Avatar.

The challenge of the Nikkor lenses is that they are entirely manual with aperture and focus knobs. This is generally not an issue for videography which is my intended use but I wanted to check how does this lens work for photography as many people still rave about it.

Lenses compatible with the adapter are UW 15, UW 20 and UW 85 full manual. Later autofocus lenses are not supported.

The Rig

My rig is a classic derivation from wide angle with 8″ and 12″ arm segments and my trusty (!) Sea and Sea YS-D2.

The Nikkor weights around 600 grams and gives almost zero lift so this rig was over 300 grams negative in fresh water.

Before using it you need to assemble the lens on the adapter.

You have two parts that can be removed to allow the lens to mount depending on your preference. I set the lens with the display upright so I could try and see it while shooting.

The controls are located on the left side side and bottom which is where I normally have my levers.

On the right you will see the display scales.

I have to say I was a bit nervous setting this on my A1 considering that this is a lens that is 25 years old at least but the vacuum test was fine so ready to go to the pool with the friends at Rec2Tec Bletchley.

The UW 15 Construction

The Nikkor lenses were generally rectilinear. The 15mm has a field of view equivalent to 20mm so only 94 degrees on the diagonal.

The approach was to correct the water distortion until such point when the image becomes rectilinear and eliminate other aberrations.

I have to say that the amount of chromatic aberrations is practically non existant.

Rectilinear lenses have gone out of fashion since dome ports with fisheye distortion being the preferred look for wide angle in modern underwater photography. For video though straight lines have a value.

Pool Session

Using this lens on the Sony A1 proved challenging for photography. Nailing the focus using peaking did not feel particularly precise.

Some shots may have been sharp enough on film resolution but with the 50 megapixels of the A1 even the slightest misfocus shows.

My productivity was quite low at the beginning as I was trying to get a hand of the lens.

The lens itself is by all means extremely sharp even for my camera.

I worked out that I could not do what I normally do which is to frame first and focus after as by the time I had nailed the focus things would have moved so I decided to set the focus and move forward or back until I thought I had my target in focus.

The situation started to improve.

I felt I had worked out how to use the lens so started looking for some subjects. During those sessions you see all sort of stuff as people practice their skills.

Considerations on the controls

I believe that the average underwater photographer shooting digital will find it very hard to use this lens and will end up shooting at f/8 or smaller apertures so that focussing becomes easier. The lens is especially challenging as it is not particularly wide so you do need strobe power.

I found really hard the lack of display of aperture and focus position. The lens is designed for much smaller Nikonos housing, with my A1 housing being more bulky you need to actually turn and look at the lens to check your settings so many times I did not have the right aperture of focus and it all was pretty laborious. In a video situation for wide angle this lens will work just fine with set and forget at 4K but to nail focus on a high megapixel camera is a hard task.

When you do get the focus though the image is outstanding.

I tried a selfie to check the focus scale and it worked well.

Consider that the most shots were at f/5.6 or f/8.

As you have no exif data it is impossible to remember what you shot unless you write it down on a slate.

Is it worth it?

The answer depends on your use case and if you already had the lens.

The following use cases fit the Nikkor UW 15 pretty well:

Videos of sharks or pelagic that do not come too close where ambient light is low
Photos at mid range with fairly static scenes where you want straight lines for example fashion models

The lens is definitely not easy to use for dynamic shots, situations where you need to get very close (as it does not focus very close) and where you need to continuosly adjust focus.

In terms of costs in GBP you are looking at:

£474 Nauticam Nikonos Adapter 37202

£300-500 Second hand Nikkor UW15

Obviously if you already have the lens and you are in one of the above use cases I would recommend you get an adapter and give it a go perhaps looking on the second hand market.

If instead you do not have the lens I would say not to bother unless money is no object, you are in the two use cases above and you have sufficent dexterity to control this lens.

Undewater photography has moved forward a great deal thanks to autofocus and although the Nikkor UW 15 is really sharp getting critical focus right is not easy. When it comes to video where you do not normally use autofocus for wide angle this lens is really interesting.

You can shoot at f/5.6 even f/4 subjects in the distance in ambient light with extremely clear and sharp detail at a fraction of the cost of other water contact optics. If you do not own any of the WACP or WWL I would say the UW 15 deserves some considerations but only if your command of depth of field and focus is very good otherwise it is better to pass.

Sony A1, Underwater Photography, UNDERWATER VIDEO

Moving to Full Frame without increasing bulk or at least not excessively!

February 4, 2023 interceptor121 Leave a comment

Many things have changed since Helen housed her Canon Ixus65 in a polycarbonate housing.

Compact cameras are practically extinct and those left have either a port system as the lens is too long or a shorter 24-70mm equivalent lens which is not useful.

Nauticam developed the N85 port system for Sony APSC (also small form factor) and Micro Four Thirds and since mid 2010s those are the prevaling systems for interchangeable lens system underwater.

APSC in the mirrorless Sony format and today Fuji has lacked native fisheye lenses and been plagued by slow flash sync speed and challenges of battery life.

When it comes to DSLR there is no significant size difference between APSC and full frame when you look at the body but moving into lenses there is a substantial difference with the Tokina 10-17mm being the lens of choice for a compact set up for both Nikon and Canon shooters.

Moving to full frame DSLR has meant historically larger ports bigger lenses and a lot more weight especially if you consider larger domes or the newer water contact optics all in excess of 2Kg and frequently more.

When you look at mirrorless the newer Nikon and Canon systems all use the N120 port system so there is no size difference between DSLR and Mirrorless.

In addition if you are already using N120 dome ports like I am you will soon find out that depending on your housing the weight benefit is not entirely there even for Sony camera whose housing are lighter and use the N100 port system. However housing are in general lighter up to 800 grams less.

Today if you want to have a portable ILC camera for photography you are really only looking at the Olympus/ OM Systems range.

If you have made the choice to get larger N120 ports or you have a Panasonic GH series your housing is already pretty big and moving to full frame will impact only when it comes to certain ports.

Let’s dive into this topic.

Here a first perspective of the A1 housing vs the GH5 housing.

Rear side view

Rear view note how the Sony has joystick controls

And finally top view

You can see that the A1 housing is a bit thicker a bit wider but not a great deal and the GH5 is taller.

Dimensions

340mm

× 169mm (H) × 125mm (D)

A1 Dimensions

Dimensions

331mm

× 184mm (H) × 110mm (D)

GH5 Dimensions

Looking at the weight on the scale

Difference is 320 grams the weigtht are higher than reported as there is a vacuum valve installed.

This means that as the GH5 system was already heavy due to the clam shell housing the difference in weight will come from the lenses and ports.

As I use the N120 system for wide angle already the difference in that use case would come from larger adapter weight or larger ports.

For flat ports on the N85 system there will be instead a weight disadvantage due to the different diameter but this is less than the delta between N85 and N120.

In my future posts I will show my port system for the Sony A1 that has the objective of:

Reducing bulk without totally compromising image quality
Use as much as possible ports I already had
Reduce the overall number of parts and adapters
Offer complete focal range coverage for wide angle

As you will see my macro choices will not go into a direction of reducing weight or bulk but there is a reason for that. You could argue that by using the GH5 and the N120 system I had already killed portability and that is true however unless you want to shoot native lenses on Olympus system there are no real better options to keep image quality and still be relatively light.

~~Stay tuned for the next articles that will introduce my choices for:~~

Index of articles with my choice of lenses and ports (continuosly updated):

Sony A1, Underwater Photography, UNDERWATER VIDEO

Sony FE 28-60mm f/4-f/5.6 Close up tests

January 24, 2023 interceptor121 4 Comments

The Sony 28/60mm f/4-f/5.6 is a small lens that was initially provided a kit lens for the Sony A7C a 24 megapixel low end camera.

There have been several discussion on underwater forum about the performance of water contact optics adapters to see what is best etc etc.

However I could not find any proper resolution test for this lens so I thought of giving it a go myself.

Dpreview has a decent sample gallery.

Official Test Data from Sony

You can find the lens specifications on Sony website https://www.sony.co.uk/electronics/camera-lenses/sel2860/specifications

The lens is nothin special mostly plastic but it is weather sealed. It has only 7 aperture blades so this is a lens for snapping around happily topside but not exactly a top of the range device.

The construction comprises 8 elements in 7 groups. Sony publishes the MFT resolution chart for this lens on their website.

Sony has some strange nomenclature however for reference images [3] is at 28mm f/4 and [4] 28mm at f/8.

[5] and [6] are at 60mm less interesting for underwater purposes.

The red lines indicate a resolution of 10 lp/mm which is a really low value (the A1 sensor resolves up to 120 lp/mm). The blue lines indicate 30 lp/mm, The [10] indicates Sagittal and [11] meridional lines.

Read this excellent article from Nikon on MTF to understand how to read the graph.

What graphic [3] is telling us is that as we move away from the centre of the frame both sagittal and meridional lines drop in contrast.

Graph [4] shows that at f/8 the deterioration as we move towards the edge of the frame is more contained neverthless meriodional lines drop considerably.

While we cannot conclude how this lens will compare to other lenses what we see from the MFT is that the 28-60mm as tested performs better at f/8 than it does at f/4 when used at 28mm. In fairness it seems to be the same situation at 60mm but the gap between f/4 and f/8 is much less.

I found a good test here aligned to what you will read here to a good extent.

Practical Home Made Test

I sourced a cushion with a complex embroided decoration.

With the camera on a tripod a remote release and one off camera strobe I took shots at f/4 f/5.6 f/8 and f/11. I run tests with the camera poiting at the centre with field of curvature and off centre with the centre of the cushion at the edges.

Here are my findings.

Centre Performance

As anticipated the lens is not sharper in the center when wide open.

At f/5.6 the difference with f/8 is minimal

Stopping down to f/11 gives a mild deterioration.

Looking at centre I would say f/5.6 to f/8 is the way to go.

Edge Performance

Let’s see the situation at the edges.

f/4 was not better in the centre and is pretty bad at the edge.

Stopping down to f/8 sees an improvement the situation is not great though.

At f/11 the edges are ok.

So looking at edge performance I would use this lens between f/8 and f/11.

Full resolution examples here

Consideration for use underwater

Looking at the lens in isolation I would think the starting point is f/8 with one stop up or down depending on the situation. This lens is not good wide open and beyond f/11 resolution starts to drop.

Alex Mustard has taken some comparison shots between the WACP-1 and the WWL-1 and his conclusion is that the performance of the WACP-1 at f/4 is similar to the WWL-1 at f/6.3. Based on my tests I would frankly not bother shooting this lens at f/4 the quality is just not there. The starting point would be f/8 and f/11 does not deteriorate edge performance that much but of course needs more light. Wider aperture like f/5.6 may be good for blue water shots.

My opinion is that this lens will not offer amazing sharpness no matter which adapter you use and is likely to stop at 26-28 megapixel in reality if not less depending on conditions, assuming your starting point is a camera with more than 40 megapixels.

it would be interesting to compare the water contact options at the aperture of f/8 and f/11 but we can safely conclude that the 28-60mm is not going to be a champion for ambient light shots in low light because the performance wide open is not great.

If I had to invest into the best image quality I would be looking at a different master lens and a larger water contact optic such as the WACP-1.

Additional Information

I have created some stir on the fact that this lens is quite weak but it actually is.

I took the same shots with my 24-70mm GMII and I can say that there are 3 stops difference at the edges between those lenses

The 24-70 at 28mm at f/4 is the same of the 28-60mm at f/11

This is a 200% crop of the edges

Left 24-70 GM at 28mm f/4 Right 28-60mm at 28mm f/11

Sony A1

Sony A1/A7S3 : Video Codecs

December 5, 2022 interceptor121 5 Comments

The A1 and A7S3 share the same codecs and format for (4K) video. The cameras have been around a few years however I could not find a proper analysis of the codecs. You can find the usual YouTube doing some qualitative analysis mostly lacking rigour and based on static charts which is not really sufficient.

I did this analysis on my A1 but the results hold for the A7S3.

So I decided to give it my own attention and you will get my findings in this post. I do not shoot 8K and for this format the choices are limited anyway to XAVC HS so not much to go about.

XAVC Basics

Sony has like many other brands their own codec for in camera video recording and their version is called XAVC.

You can find some more detailed information on Sony Pro Site.

Take into account that the documentation does not consider the newest XAVC HS based on HEVC coding.

In general terms you have two options:

Intra frame -> each frame is self contained and does not depend on other frames, the clip is a collection of compressed images
Group of Pictures (GOP) -> frames are a combination of 1 reference intraframe for each group of pictures and multiple P and B frames which means respectively Predicted and Bi-directional predicted.

A1 Codec Options

As mentioned XAVC gives you both options and the A1/A7S3 can record Intra video up to 240,250,300,600 Mbps depending on the frame rate Sony approach is 10mbps per frame.

GOP is more compressed and has 140,200,280 Mbps respectively for 24/25/30, 50/60, 100/120 frames per second. Please note higher frame rate of 100/120 fps is only supported on GOP formats as it would otherwise reach 1.2 Gbps.

Higher compression does not mean at all lower quality, analysing all codecs using ffprobe you can see that the individual Intra frames within a GOP structure are larger than the Intra frames of an All-Intra clip at higher bit rate. However due to the nature of GOP there will be potentially motion prediction errors and more noise.

A1 Sample Video

I ran some tests of a music box both static and in motion using Slog3. I warmly recommend using Slog3 for all your video as it the log compression achieves less bit utilisation and makes the video compression even more efficient.

From what I can see (there is a small focus error on the XAVC S moving part) there are minimal difference in motion handling and minimal differences on noise.

I checked each clip with Neat video using the same reference area. XAVC S and HS return the same amount of noise.

While All intra for some reason has less noise. I believe this is because the prediction introduce some small error themselves.

Considering those shots are taken at ISO 4000 there is not much to complain. ISO 4000 in Slog3 is the point where dual conversion gain goes into High gain. If you use a standard profile this would be 500. I do not recommend shooting the A1 or A7S3 in any other picture profile than slog3.

Visual Differences between Codecs

I frankly cannot see much of a difference between those codecs, I have also shot a few sequences in APSC in equivalence so at ISO 2000 and f/3.2 instead of f/4.5 and I could not see much difference except APSC has a bit more noise as expected.

Analysis

The following table shows some key data points and my observation based on a series of 50 fps video test shots with the A1.

You can see that the key difference between the codecs is the bitrate, the edit effort (how taxing is on your machine) and the noise.

What codec you will use depends mostly on practical considerations as the difference in image quality are intangible.

The HS format which is based on HEVC has a single reference frame each second which means this codec is really for static scenes as most frame are predicted. XAVC HS biggest limitation is the lack of 25/30 fps options it is a good choice for 24 fps and it does not completely stall your machine in the editing.

The S variation is good in terms of space saving as well as generally being effective for motion however it is the hardest one to edit. If space is a problem and you are happy to convert or edit natively XAVC S is a good option. If you need something that can go on for long and manages almost all situations the XAVC S should be your choice however unless you have a workstation that supports accelerated H264 10 bits 422 (and there are not many at all) you will need to convert to an intermediate codec spending more time in post processing.

Finally the S-I All intra is the one that has the least noise and is more demanding on your memory card but is the easiest one to edit and play despite the higher bit rate. If you shoot wildlife, actions, or use gimbals and your default is 50/60 frames per second, the All intra codec XAVC S-I is the best option but it does not support higher frame rate so you would need to switch to another codec for those situations and this should be the XAVC S as it manages motion better.

I have not done a test with a gimbal but those scenario where a lot of pixel move in the frame is much more taking than my music box test.

Conclusion

Although the choice of codecs is not as rich as Panasonic cameras and there are no formats other than 16:9 there are no quality issues with the A1 and A7S3 codecs as long as you shoot in Slog3.

Obviously there are options for external recording although this is not the best option for run and gun and that would give you ProRes 422 HQ or ProRes RAW with huge files easier to edit. In the future I will do a comparison between the internal intra codec and ProRes 422 as well as ProRes 422 HQ so stay tuned.

If you have any question leave a comment and I will follow up.

Sony A1

Sony A1 : Video Resolution

December 3, 2022 interceptor121 6 Comments

When you buy a new camera some time after the initial release date you are lucky to find all sorts of videos of other geeks like you that have been testing.

I was referred to this video that shows quite a few quirks of the Sony A1. Gerald has since confirmed the A1 video is binned not line skipped.

You can’t always rely on third party so here are a number of geek tests.

The first question was do you need to shoot ASPC or full frame. APSC is scaled while full frame is binned which means the first may look better than the second but will have more noise.

Pixel Binning

As usual there is no official documentation of the camera inner workings but this diagram should help explain a few things.

On the upstream the potential flow for a classic bayer filter camera to accomplish binning (it is a guess). On the bottom what a mobile phone may be doing.

In the first case binning results in a reduction of resolution and potential artifacts. In the second only a reduction of resolution.

Now one of the question is what if we just crop the sensor in APSC and then scale down will it look better?

I have done exactly this test and the answer seems to be no.

UHD binned vs APSC scaled

In theory the binning should look much worse but what I have seen is that moire kicks off for both at around 2x the focal length of the other. So if APSC gives moire at 50mm full frame will give it at 100mm. The full frame moire is more severe when it occurs but in most cases you cannot tell the APSC and binned UHD apart in conditions of good light.

other side by side of a dpreview sample shot cropped again there is moire in their situation on the full frame but in effect the image quality is identical.

So personally am not going to bother with APSC unless I need more magnification and I am not in low light. For all the rest I will use full frame binned.

ProRes RAW

The A1 also provides its pixel binning mode in ProRes RAW and it is identical to the internal recording when the lens corrections are off. ProRes RAW does not have a concept of lens profile so you get all the lovely defect of your lens. To my horror e-mount leses have many defects, all are distorted and have significant amount of CA.

ProRes RAW vs Internal

In short unless you have a DSLR adapted lens with zero defects those aberrations are troublesome so with native glass am skipping ProRes RAW altogether.

4K with External Recorders

If you have a Ninja consistent to what Gerald Undone says you can get a scaled down version of 8K setting your HDMI output to Auto or 2160. Auto generates 4k60fps while 2160 gives you the same frame rate of your 8K.

Interestingly if you do not record to card the HDMI output goes back to what you get in internal recording. So in short you need to record 8K to card which means eventually overheating. It is unclear what subsampling is being output howeverthe image does look a bit cleaner.

8K vs 4K

There is no doubt that the 8K mode although only available up to 30 fps is superior however editing the 580 mbps HEVC files is not that easy.

I personally shoot in 4K so I am set on the full frame binned 4K but if you have the hardware to process and the screen to watch 8K is the way forward. Gerald Undone trick of the HDMI 4K while shooting also works but be careful with overheating.

Coming Soon

Next article will break down the codecs available with the A1.

Sony A1

Sony A1 : The One or Two Face?

November 30, 2022 interceptor121 Leave a comment

I have been looking for a camera that would be a significant upgrade from my GH5M2 for some time and I have narrowed my options to two choices: the Sony A1 and the Canon R5. As the A1 underwater port system can use most of my glass I have recently acquired the A1.

Did I get the upgrade I was looking for? For photos I would say the answer has been an immediate yes due to the amazing autofocus and EVF of this camera and the burst rate. For me 15 fps is enough but the fact the A1 can trigger a flash with electronic shutter at 1/200 of a second is amazing. But I still like the mechanical shutter (unlike the Z9) and this goes to 1/400 which is also a first.

Let’s have a look at the A1 and where it stands at the end of 2022.

The Sony A1 was announced in January 2021 and was at that time the fastest, high resolution (>42 MP) full frame camera on the market.

Capable of producing 20 fps continuous autofocus at staggering 50MP and 30 fps JPEG it still is the full frame camera producing the highest resolution at the highest frame rate as the Nikon Z9 has the same frame rate but lower sensor resolution.

As new cameras have come along we have seen some development especially on the video front and while the Sony A1 can produce ProRes RAW this is at half resolution (4230×2430) the Canon R5 is able to output 8192 x 4320.

キヤノンEOS R5外付け8K ProRes RAW ダイナミックレンジラボテスト

Users have been curious on why the Canon R5 can do that while the A1 can’t and also why does the Z9 produce ProRes RAW internally at half resolution, so similar to the A1 and NRAW (that is likely not RAW) at full resolution?

Various tests on video show that both the Z9 and A1 outperform the Canon R5 in video on all formats.

Sony A1 Lab Test – Rolling Shutter, Dynamic Range and Latitude

Interestingly SNR improves 0.8 stops moving from 8K to 4K full frame which would not be possible if the camera was skipping pixels.

But of course neither the Z9 nor A1 can produce external ProRes RAW 8K and users have been screaming at Sony.

Investigations

I was quite suspicious of the fact that the Z9 can only record internal raw and I have noted that Nikon has pushed back on RED lawsuit on RAW recording and therefore I believe NRAW is actually demosaiced.

I looked at dpreview studio scene and compared those cameras and in addition added also the Panasonic SR1 to check the image quality.

You can see how all cameras are affected by false color artefacts, the A1 and Z9 much more than others.

Moire is not an issue

The other suspicious fact is that the A1 and Z9 produce ProRes RAW at half resolution. How can the camera produce RAW at half resolution with no false colour artefacts if the 2×2 cell is made of different colours?

If you follow mobile phone technology, you are familiar with the super high resolution claim of certain phones, this article on Sony semiconductors web page provides an insight

The actual pixels are arranged in cells of 4 of the same colour and to produce the high resolution image the pixels are re-mosaiced, which in turn could produce artefacts. This technology has been mainstream for at least 4 years.

If you look at this video you can see that ProRes RAW video no longer produces false colour artefacts but is prone to moire as the camera does not have a low pass filter.

Dpreview studio scene provides some additional insight looking at video grabs.

No false color in 4k video

Moire in 4k video due to low resolution generating aliasing

My conclusion is that the A1 as well as the Z9 are cheating. Unlike the Canon R5 they are based on a quad-bayer sensor cell and therefore will not offer the same color resolution at 1:1 pixel of the canon R5.

It has already been proven that the A7S3 has a quad bayer cell.

Measures like DxOMark color depth do not look at color errors so this will not be spotted but I believe the remosaic of pixels of the same colour is the issue here that is showing in the dpreview studio scene.

There has been additional debate then on why the A1 defaults to APSC mode when producing 4K video, this is counterintuitive however the APSC image does not have moire nor false colour.

If we carry on with the assumption that what I have written here is correct, we can have a look at the required bandwidth to read the sensor and produce video output at various resolution and frame rates

H	V	Depth	FPS	Bandwidth	RGB Bandwidth	Subsampled
8640	4860	12	30	15.116544	45.349632	22.674816
5760	3240	12	60	13.436928	40.310784	26.873856
4320	2430	12	60	7.558272	22.674816	15.116544
3840	2160	12	120	11.943936	35.831808	23.887872
2880	1620	12	120	6.718464	20.155392	13.436928

Bandwidth Gbps for various video resolutions

Considering a readout at 12 bits we can see that the highest bandwidth is for the 8K and the 4k APSC mode as the other modes have less pixels even the 120 fps does not get to that bandwidth however required a faster sensor scan and is cropped

When the raw data goes in the image pipeline it is converted into RGB signal and here we can see that after subsampling the ASPC format has the highest data volume due to the 422 subsampling.

This in turn produces the least artefacts in fact it is quite resistant to moire as anti aliasing can be performed in camera using different techniques. So this is why APSC footage from the A1 is smoother but not necessarily sharper in fact the opposite.

A different current of thought may say no it is a full resolution classic bayer filter array which is then binned for 4k video however

Such technology does not exist is not advertised there are no patents
The remosaic of quad bayer sensor has been mainstream in mobile phones for years now and is done on chip

So my take is Sony is just leveraging mobile phone technology for the IMX610 in the A1 but I am open to the challenge.

For clarity as some readers seem not to understand I believe the camera has a total of 50 megapixels arranged in a quad bayer cell and goes to 12.5 in video 4K full frame combining pixels in 2×2 cells. There are phones on the market with 108 megapixels so this is nothing new.

The A1 is produced on the Exmor RS line which has been developed for mobile technology so no suprise the same investement is leveraged for cameras.

Many commercially available phones already implement the same features of the A1 see for example the specs of the Xiaomi12

Video Format Choice

The other question is then what to shoot now that we know or think we know the inner workings of the camera?

8K suffers from similar false colour artefacts of still images and 8k displays are rare it is only available in 4:2:0 subsampling due to bandwidth issues.
APSC is cropped while the image has no defect this mode does not have a benefit on other cameras like the Panasonic GH6, it also does not support 120fps. Many other cameras offer cropped APSC 4k footage: you do not need an A1 if you want APSC video.
UHD has moire in certain situations due to the lower resolution being out resolved by the lenses used and the lack of anti aliasing filter however it does offer the highest dynamic range and no false colour artefacts

My approach is to use UHD and if I have moire, use APSC. Moire is visible in the EVF so you can then mitigate it by switching to APSC only when required.

I have done a full analysis of the codecs and frames which I will post in a later article.

The other consideration is that I did not get a full frame camera to shoot it in APSC and in fact the A1 APSC also looks the same as my Panasonic GH5M2 and offers minimal benefit of DR and SNR due to the smaller size of the cropped area.

Now that I know (or think I know!) What may be behind the A1 limitations, am I disappointed? Actually I am not. I did not buy this camera for 8K, I have no ability to edit or display 8k but I wanted an upgrade to 4k and I can say the A1 holds video footage at 12800 ISO in slog3. I have yet to see any moire and prores raw 4k@60 is amazing quality, surely there is distortion and chromatic aberrations and vignetting but especially underwater or topside long lens this is not an issue. I am a bit disappointed by the codecs on card especially as HEVC does not have a 30 fps mode however overall the camera delivers an extremely pleasing image quality in 4K with outstanding clean colours using slog3/cine.gamut. If there is one thing that is weak is the IBIS.

If you are a purist and want the best image quality in full sensor should you look at the canon R5? This is where it gets interesting. I believe the R5 has a cleaner image however Canon is behind in terms of sensor technology so at the end when you look at real life images in terms of IQ and SNR I do not see the Canon taking an edge. What the Canon is better at is ergonomics, menu systems but not ultimately image quality despite all the things discussed here.

Conclusion

Despite all the cheating the A1 remains an amazing camera, it is small, it has many lens options and has the best underwater ports option and I do not regret my choice in fact I look forward to using this underwater. And finally, all of this just made me reflect on what a great camera the Panasonic GH5M2 is and I will keep it for some time until I am happy with all use cases.

Underwater Performance Context

Sony A1 WWL-1 Rig

Pool Tests

Edge Sharpness

Comparison to Rectilinear lenses

Conclusion

Dome Options 140mm vs 4.33″

Building the Rig

Pool Session

Shots at f/11

Shots at f/16

Shots at f/22

Conclusion

Myth Busting

Properties of fisheye lens as per UWPG:

Fisheye lenses and Dome Ports

Domes, field of curvature and Fisheye lenses

What does all of the above mean?

Underwater proof of concept

Conclusion

The Rig

The UW 15 Construction

Pool Session

Considerations on the controls

Is it worth it?

Official Test Data from Sony

Practical Home Made Test

Centre Performance

Edge Performance

Consideration for use underwater

Additional Information

XAVC Basics

A1 Codec Options

A1 Sample Video

Visual Differences between Codecs

Analysis

Conclusion

Pixel Binning

ProRes RAW

4K with External Recorders

8K vs 4K

Coming Soon

Investigations

Video Format Choice

Conclusion

Wildlife photography made easy