As we know the Sony RX100 cameras, we will refer to both Mark I and II as the lens is the same, do not offer the best out of the box super close up performance.
To be clear no compact camera really does macro, as no compact can capture an area 36×24 mm in size without being on top of the subject and having a shadow cast on it.
The RX100 however are particularly unexciting as the capture area is pretty large at 76x51mm at the minimum focus distance of 5cm. This means a reproduction factor of less than 1:2 so things are half life size in traditional terms.
In water the minimum focus distance increases and so does magnification so performance is all in all the same.
This means that a typical small subject like a medium size nudibranch measuring 4cm will fill a bit more than half the frame, not great.
The problem can be addressed by close up lenses that have a set power that determines the focal length and working distance where we can use the full camera zoom.
So the close up lens sets the working distance whilst the camera zoom sets the magnification.
A typical close up lens will have a power of 5 or 6 diopters with a working distance in water of 200 or 165mm, what does it mean for the RX100?
I have done some testing in water using a ruler and an Inon UCL165 this is the result:
Our capture width is now 46mm so our 4cm nudibranch will nearly fill the frame. The working distance of this lens is 165mm so this is a very versatile solution as most critters have no problem being approached so close.
What happens with a +10 close up lens with a focal length of 100mm, this is another test
A +10 diopter like the Subsee or Inon UCL100 achieves exactly 35mm so life size macro. However a lens like this will not focus at longer focal distances without zooming out, furthermore there are plenty of subject that do not need this magnification.
Close up lenses can be stacked so this is the result of two + 6 diopters
The width is now 32mm which is 1.1:1 so more than macro. This is adequate even for pygmy seahorse and with the incredible resolution of the RX100 cropping is not a big issue. Working distance is around 8.5cm which is still tolerated by small critters.
For completeness I have also tested a +16 combination
At around 26mm this is 1.4:1 so real super macro, the working distance is however only 6.25cm which is really close and will scare most critters away.
Without any close up lens the RX100 can only capture 5cm objects without extensive cropping
A close up lens with a working distance of 165mm allows for most of the critters we consider small but without super macro effects unless cropped
Two stacked +6 diopters offer super macro and can also be cropped for more suggestive effect
A single +10 close up lens achieves real macro however it is not versatile enough for every day usage
Stacking lenses does introduce chromatic aberration but this can be eliminated in photos and is barely noticed in video
Pay attention when you select your close up lenses that the focal distance that is in the specification is measured in water otherwise you will find yourself with a useless purchase
I have been fortunate to receive one of the first RX100M2 that have reached the market so I thought of sharing with you my first impression and what I believe will be the potential for underwater imaging use.
This is the link to the unboxing video of the camera
I posted a summary of the RX100 capabilities for underwater video some time ago on this blog the post is here:
Probably the best thing is to revisit my review and update any significant differences between the RX100 Mark 2 and the original version which is still on the market and will remain at least until the end of 2013.
Bright Lens – Not changed
The RX100M2 has exactly the same lens of its predecessor RX100, it is true that when zoomed the minimum aperture drops down to f/4.9 however this is not a concern for underwater imaging as usually long focal lengths are for macro and we are interested in very small aperture to allow for greater depth of field.
Low Noise – Improvement!
In virtue of the new retro illuminated sensor the mark 2 has one full f-stop advantage over the original RX100. This means that ISO800 is a breeze and potentially we could go as low as ISO1600. I would not do that but what it means is a cleaner image at depth in ambient light.
Image Quality – Improvement
Image quality is outstanding and the lack of aggressive contract and sharpness filters in the default settings means more room for correction in post processing.
Video Mode Control – no change
The RX100 had complete control on video mode and the mark 2 maintains the standard. Very important is that the program mode is excellent and keeps the shutter speed at 1/100 or 1/125 when used in active mode which is ideal for 50/60p smooth footage.
Manual Focus – no change
Same as for the RX100
Battery Life – Improvement
According to Sony battery life has improved from an already outstanding CIPA 330 to a declared value of CIPA 350. The new Mark 2 has also an hot shoe so in theory if any manufactures produces a wired TTL enabled housing this means plenty of shooting before changing the battery pack. We suspect though that only ikelite will have this option on the housing.
Active Steadyshot – no change
I initially slagged the RX100 stabilization system based on performance on land. However at a more in depth analysis it turns out that the RX100 active steadyshot, even if at cost of an image crop is very effective for sudden camera movement and for high magnification macro. The Stabilizer is not as sticky as others so when you eventually vibrate it does not jump. Although the performance for stills is poor to irrelevant and so is the normal mode the active mode is very effective for underwater use. The mark 2 is built exactly with the same algorithm and combination of optical and electronic.
Tedious Workarounds Comparison
Some of the ergonomics of the RX100 are not the best and seriously deduct from an otherwise excellent experience, the most annoying issues:
Lack of focus lock – no change
For some reason Sony decided to skip on this essential feature, the workaround involves switching to manual focus however it is then possible to accidentally change focus if the front ring is set to control focus. The RX100M2 has the same issue.
Setting Custom White Balance in Video – No change
Setting custom white balance is only possible in the still modes, while in fact if you shoot RAW don’t actually need white balancing. This is the largest non sense of this camera that requires the user to navigate out into Program to ensure white balance is set correctly and you don’t end up with the Custom WB Error message. Though this is annoying is not such a killer as it would initially seem if you take your movies in one of this still modes which is valid for wide angle and ambient light shot. For macro you will need to switch to movie mode aperture priority in AWB. If you keep this discipline this is issue is mitigated. The RX100M2 does not change this and I believe this is due to the fact that the shutter button that is used to set custom white balance is disabled in video.
Lack of 24/25/30 progressive modes at 1080HD – Improvement!
The RX100M2 shoots at 50/60p as well as 25/24p in addition to that you can switch between PAL and NTSC which is great!!!
AVCHD – Improvement!
The RX100M2 has not only the progressive modes at double frame rate but also AVCHD 1.0 compliant format, this means that if you choose the 24M 24/25 p mode you can import with all editing programs without issue. Not only that but if you use the wireless import utility this converts also the AVCHD progressive files in mp4 for you. This is great improvement
Key Weaknesses comparison
The RX100 had also some key weaknesses let’s see how the mark 2 fares.
Macro Performance – no change
Exactly the same as its predecessor the RX100M2 has a minimum focus distance of 5cm on land that becomes around 7 in water. Like with the RX100 because of the large capture area you will need diopters for macro shots. On a positive note once you have a close up lens the performance is incredible when coupled with manual focus with peaking.
Sony has adopted a lens shift approach in this camera instead of the sensor shift of the higher end alpha, maybe due to large size of the sensor compared to the camera body. They have then added some software processing in camera but the results are just average. There are many other cameras that do better than the RX100.
Soft Corners at Wide End – Improvement
The RX100 first generation had soft corners until f/5.6 the situation changes dramatically as we can see in this test card comparison shot. Not sure if there was an issue with the RX100 original sensor but this looks excellent and as sharp as the panasonic LX7 or Canon G15.
Look for yourself!!!
No Neutral Density Filter – marginal deterioration
As its predecessor there is no neutral density also on the mark2. A little tip for video is to shoot with filters that take away 1 1/3 f-stop. This is not ideal but helps. There were some speculation that because the minimum ISO in RAW is now 100 instead of 80 sunballs would be more difficult to shoot. 1/3 of an f-stop does not really make any difference I believe this is more a statement so that the RX100 housing that are in stock sell out at full price.
I have to say that the tilting screen is fantastic to shoot on a tripod on lens. I doubt any housing can accommodate for this but the feature is outstanding
And this is the rear
So the question is should I buy the RX100M2 or the RX100 maybe grabbing a deal? Recsea has already announced a housing for the mark 2 and Nauticam is working on it. I believe that when it comes to still photography the difference between the two cameras are not substantial as many shots are with strobes I have however noticed a much faster internal flash cycle time. I do not want to be definite but looks like a full dump takes around seconds to recharge. Also to be considered that in US the price difference is $100 so definitely the Mark2 is the way forward. In UK/Europe the difference on the list price is £150/€180 which is much more.
So I would say if you are planning to use the camera for video go for the RX100M2 the improvements are significant both in terms of video formats but also in terms of sharpness at wide apertures. If your main interest is photography and you live in US go for the mark 2 in Europe instead I would grab a deal on the RX100 when the price of the housing drops.
I am waiting for a test housing from Nauticam as soon as I have it I will post an unboxing video followed by some pool tests.
Inon introduced a new close up lens in February of this year the UCL100. So why did Inon come up with this after the very successful UCL165 series? Probably some pressure from products like Subsee that produce better quality images than the Inon lenses and more and more lenses with similar performance to the existing Inon lenses. So what is different about the UCL100? First of all this lens is heavy 243/269 grams in the LD/M67 version in air that become 130/151 grams in water double than the UCL165. The lens is made of 3 elements instead of two and is very similar to a Subsee this is more evident taking a look at the lens on land.
This shot is taken with the bare port at 50mm.
This is the same shot at the same working distance using the UCL100 note the magnification.
The lens behaves like a magnifying glass exactly as the Subsee, Inon has made some effort to try to reduce vignetting, this picture is taken on land at 28mm.
Note a little dark bottom right corner, the lens in fact vignettes at 24mm this is due to the huge size of the LX7 lens and may not happen with other cameras.
Here we can see the rear of the lens from the Fix adapter side. The lens sits very close to the glass port.
I have opted for a bayonet version of this lens as I will use the fix as m67 adapter if I had to dive with the wet mate.
If you are a photographer I would definitely recommend the LD bayonet version over the M67 as it is easier to remove and attach in water.
There are some other very interesting characteristics of this lens. Usually a diopter works only around a certain working distance for a given zoom so the issue with such a powerful close up lens is that if we are far away from the working distance the lens is not usable.
The UCL100 instead is quite flexible and has a huge swing of working distances for a given focal length as in the table below.
All values are in mm.
So the lens keeps working well far away the nominal 100mm and due to the construction also gives a magnifying effect this means that it is possible to take this lens in water as the only close up lens and there will not be too much of a limitation if for some reason we can’t get that close to the subject. A swing of 40mm at telephoto end is excellent and this becomes 70mm at 70mm zoom and 110 at 50mm.
What about image quality most of you will know by now how specific I am when it comes to aberrations, this is a crop of an image taken with the UCL165
You can see the yellow and purple halo around the zero.
This is a detail of the same ruler in water with the UCL100
The image is a bit soft because of the aperture used but absolutely free of any fringing that is astounding for this level of magnification, the quality of the image is same as Subsee.
This lens comes with a lens front and back cover, the front lens is a clip with lanyard. The UCL100 can also be stacked with other M67 lenses if you need more!!!
With the LX7 the UCL100 achieves a reproduction ratio of 1.1:1 compared to the 1.4:1 of an Inon UCL165. The limitation of the zoom of the LX7 shows a bit here as even the Sony RX100 gets nearly a 1:1 with this lens but the strength of the focus of the LX7 are second to no other camera in this segment so I look forward to using this lens on some really small stuff.
The UCL100 is priced at $282 in US and £275 in UK versus $225/£210 of Subsee so why would you bother getting this lens from Inon instead? I think the main selling point of this lens in addition to the image quality and magnification power is the fact that the lens operates until wide end and has a very wide range of working distances so you are not stuck just around the 100mm nominal focal lenght. This allows use of the full zoom from wide to tele that in video is especially important. For pictures I am not so sure the additional cost is justified as stills are usually at full telephoto end.
You can see in the section of the Veronica L that missing those extra degrees field of view did not allow me to take the full wreck by side even if it was not that big. On couple of reef dives I already had the Inon on the previous wreck dive so I left it you can compare performance of the two lenses in terms of sharpness and flare. Generally I feel the wet mate has less flare and is sharper however it does have an issue of reflections as covered in the previous post.
As always I have used iMovie to edit the AVCHD progressive files that I converted to normal mp4 using the workflow in a previous post. There are no dramatic alterations of colour or exposure and no stabilization has been run in any part of the video (in some parts like the snake eel moving it shows) all was done with custom white balance using the camera functionality, considering how deep were some of the wrecks this is very good I believe.
I would love your comments this was mostly an exploration trip so it is interesting to compare to the RX100 Raja Ampat videos
So I finally had the opportunity to take the LX7 on a trip after some pool tests.
After my attempts last year with the Sony RX100 I was a bit skeptical that I could actually find something better for video but I think the LX7 beats it.
I put together a sample just to give an idea of equipment used and how it works, please note this is not altered in any way
There is a picture of the rig in this blog on a specific page but let me confirm once again in detail
Nauticam LX7 housing
Ultralight TR-DM tray with extension TR-DUP and two TR-DH handles without ball.
12 segments locline arms on 3/4″ mount base and reducer on the handles
Two sola 1200
Nauticam wet mate
Inon UCL165AD on bespoke M67 adapter
Inon UWL-H100 28M67
Inon M67 double lens holder on custom mount
In a previous post I highlighted that for most the wet mate will be the only lens needed however I had some wreck dives and the 18mm of the Inon wide angle are more appropriate.
I also gave a try to the panasonic intelligent zoom that allows for 2x digital magnification and sharpening that for me works very well and you can see it in the footage. This allows a user with just the wet mate to further zoom without need of a close up lens or a use with a single +6 diopter to achieve super macro.
I found the white balance of the camera excellent on both my hand or sand. I had issues with my padi slate that many times returned a ‘scene too bright’ error. Maybe this is the reason why backscatter failed this camera for video?? Who knows.
You can see that even at 36 meters the colour are as good as they can be.
For macro shots I used the temperature setting at 6500K, I found the white balance tint fine tuning to be excellent to further enhance it.
I shot in shutter priority the whole time with shutter speed of 1/100 or 1/50 depending on conditions and type of shot. The camera autoISO and choice of aperture privilege noise reduction however as the lens of the LX7 is really sharp the relatively wide aperture did not mean soft corners.
I tried the various photo styles and at the end settled for the standard one, I found the natural really to have too little contrast.
I thought of shooting in mp4 for wide and AVCHD progressive for close up but this would have meant two different frame rates to edit, at the end I shot at the highest available setting to avoid confusion.
I had received a new port from nauticam so I had no vignette at 28mm and the full 100 degrees the inon lens can offer.
The ergonomics of the camera that have fixed commands for aperture and shutter proved to be convenient and the built in neutral density filter was very effective at shallow depth or on the surface.
In essence I think that the issues backscatter mention are non existent.
I did have a few problems with the wet lenses though.
The wet mate proved to be a great little tool very sharp and light however none of the sides of the glass have anti reflective coating. In bright scenes or backlit scenes I did not have many issues with flare however I could see the marking on the lens reflected back on the wet mate and in the picture. I suggest putting an inon anti ghost sticker or gaffer tape to hide those shining markers or to colour them with permanent black ink.
Other than this the wet mate performs very well in all reef scenes and close up of critter a few inches big.
The inon diopter did not cause any trouble other than the obvious vignetting until 70mm. One pleasant surprise is the LX7 autofocus. Having struggled with the poor focus of the RX100 at high magnification I was astonished that the LX7 finds focus even with two stacked diopters and keeps it!!! I never had to use manual focus that with the RX100 was the norm at macro range.
I had bought the UCL165 and UCL330 in m67 format but decided to sell them as I will actually switch to bayonet very soon for the wide angle.
The Inon UWL-H100 was probably the most disappointing find of the trip. Image was sharp in normal condition however this lens tends to flare quite a bit and this creates block noise in the water column in video, when I used my hand to shade the lens the flare went away. Inon sells a lens hood for the 28LD version of this lens but not for the M67 as there would be issues to align the hood petals to the frame.
Considering that the lens is very heavy in water at 350 grams and that screwing and unscrewing was a concern mid water I have decided to convert the lens into an LD bayonet. Inon sells a replacement service part for the 28LD that can be used to replace the M67 thread of the lens. Other than this part the two lenses M67 and 28LD are identical. I will use a nauticam m67 LD adapter I hope this will not increase the vignette. I will connect my AD mount close up with a AD->LD converter when using the wide angle and then use an AD->M67 converter when I use the wetmate. This saves me buying two different diopters and I can stack the two UCL165AD I already have. They do vignette a lot at medium but who cares when you shoot at full zoom.
I look forward to testing the UWL-H100 with the lens hood I am sure results will be better. On the other hand when the sunlight is behind the shots have incredible sharpness with this lens.
So the LX7 gets 5 stars from my side and I leave you with two recommendations:
1. Apply a form of anti ghost sticker to the LX7 lens
2. If you want to get the Inon UWL-H100 go for the LD mount so that you can put the lens hood on
When compact cameras were designed for 35mm it was quite common to shoot just with a camera and strobe; this allowed the average user to take decent close up pictures as long as the camera was capable of focusing within a couple of inches from the subject.
Years later manufacturers started introducing wider lenses first came 28mm equivalent and most recently 24mm, these cameras give an increased field of view on land of 75 and 84 degrees diagonal.
So why is it a bad idea to shoot just with the bare camera and no add-on lenses?
Two key reasons:
Once in water the 84 degrees diagonal of a 24mm equivalent camera reduce to 54 or less because of the water medium
At focal lengths shorter than 35mm pincushion distortion becomes stronger to the point the pictures are awful.
So if you plan to use your wider compact camera underwater without lenses make sure you zoom to 35mm to avoid distortion.
This is the same picture at 35mm note how the image is now rectilinear.
At 35mm we are back were we were in the mid 2000 and all we can do is close-ups so there is no advantage having a wider lens for underwater use with a compact.
Another common misconception is that a compact camera takes great macro just with the internal flash. Firstly a macro picture has a 24mm height of the capture area, nearly no compacts on the market are capable of this: the Panasonic LX7 and the Canon G15 within the current range are the exceptions. However at 1cm distance the internal flash is completely obscured by the lens, which means there really is no macro without a strobe and a close up lens: all you can shoot are close-ups.
This explains the need for wet lenses in water, wide-angle lenses to increase the field of view and allow us to get closer and take advantage of artificial lighting, close up lenses that also allow us to get closer using the full zoom of the camera and shoot at increased magnification without being on top of our subject.
The needs of photography and video differ as lighting tools differ, photos require strobe to freeze motion, video instead uses fixed lights. Photos are also taken at much wider angle than videos and fisheye effect is accepted, an effect that in video is generally not welcome.
With this in mind what are the wet lens options for the Panasonic LX7?
It depends of course on the planned usage of the camera.
The LX7 has extremely good close up capabilities out of the box, however the capture area is around 12×8 cm that is not exactly small. If we want our nudibranch of shrimp to fill more of the frame we need a close up lens.
From my tests the Inon UCL165 brings around 2.5x magnification with the LX7.
I have tried stacking two UCL165 but the amount of chromatic aberration is too much for my liking, I found that 9 diopters is the max before fringing becomes a real problem and I do not recommend stacking two of those lenses or two equivalent Dyron diopters. I think the most flexible set up is a UCL165 and UCL330, this covers all possible working distances. I do not have a UCL330 yet so I can confirm but I have taken shots with a very similar lens (Olympus PTMC-01) and the results are excellent with a capture area of 48×32 mm that is very close to real macro. The zoom of the LX7 is the real limit here as it maxes out at 90mm versus the 120 of a Canon S110 or 140 of the Canon G15.
For close focus and ambient light wide-angle the bad news is that there is no fisheye lens that works well with the LX7 this is due to the extremely large lens.
I have tested the Inon UWL-H100 and I had to wait for a new port to be delivered from Nauticam as their original one was too long and had vignetting even at 28mm. This lens yields more than 100 degrees diagonal and is my preferred choice for the LX7 for stills. There is however a good amount of blue and yellow fringing if I really have to be picky so the extended field of view comes at some price.
I use Inon lenses however a possible candidate is the Epoque DCL30, this lens is reported to work with 28mm equivalent cameras however the rear lens is smaller than the Inon so I believe this needs confirmation. There is a $70 difference in US and £70 here in UK between the two lenses and considering that a dome will not worth I encourage testing this lens as the results may be acceptable. I think bluewater photo markets this lens in US under their own brand.
If you plan to use the LX7 for video the situation is different, as the camera close up performance is extremely good and usually macro video is very hard. Most time we shoot with ambient light and if visibility is acceptable getting that close is not so important considering the LX7 ability to manipulate white balance.
The first suggestion is to get a Nauticam Wet Mate, this is a sealed air dome that gives us back the air field of view and works extremely well without any chromatic aberration and extremely sharp corners. This lens keeps the image rectilinear that is also a good thing for video.
For majority of reef dives the wet mate is all is needed as this also allows the full use of the zoom without soft corners that occur if you zoom into a wet wide-angle lens. This lens is the most versatile for general video use and costs $250, great value from Nauticam.
There are however specific situations where the wet mate is not sufficient, as before close up performance with the bare port is good but not great for smaller critter, so a close up lens would be the next addition, again an Inon UCL165 or a Dyron Double Diopter would work just fine and have the same power.
When shooting at closer distance with lights, or when there is large fish or wrecks a wet lens is important as the 84 degrees diagonal of the LX7 are actually only 76 horizontal. Again the Inon UWL-H100 is my choice but would check again for the Epoque DCL-30. One characteristic of the LX7 that is interesting is that the diagonal field of view of the camera remains constant when picture format changes, this means the horizontal field of view is larger at 16:9 movie mode than it is at 3:2 for pictures.
Field of view with the LX7
Those are the maximum angles of coverage horizontal of the LX7 as I measured them at 3:2:
Bare Port 24mm: 50°
Wet mate 24mm: 71.5°
Inon UWL-H100: 88°
At 16:9 there is a wider field of view of:
Bare Port 24mm: 54°
Wet mate 24mm: 76.2°
Inon UWL-H100: 93°
In general terms with the wet mate we can cover 1.56x the horizontal field of view of the flat port and with the wide-angle 2.1x.
The wide-angle offers an additional 35% over the wet mate don’t be mislead by the apparent small difference between 84° and 100° as those are diagonal measures not horizontal and those few degrees more count.
At 1 meter distance the maximum subject size with the wet mate in movie mode is 1.56 meters and with the wide-angle this becomes 2.1, that confirms that the wet-mate is good for general use and the wide-angle is only required for close scenes of larger fish or wrecks.
Those are the three lenses I have used for those tests. A final consideration is about the lens mount. I will use the LX7 for video so my choice has been a 67mm mount, because this is the only format that the wet-mate offers.
If I was using the LX7 only for pictures I would prefer the flexibility of the Inon LD mount even if this costs a bit more as it makes it so much easier to swap lenses in water when you have a bayonet mount.
There is always a lot of confusion around macro photography and close up lenses. It is useful to set some definitions right before going into selecting the appropriate lens.
In traditional terms a macro photograph is one where the image of the subject on the sensor is the same size of the subject itself. As photography is based on 35mm film this means that a macro photograph is one where the vertical size of the frame measures 24mm. If we look at high-end compact cameras there are very few that are able to capture an area smaller than 35×24 mm, among those the Canon G15 or the Panasonic LX7. Majority of other cameras capture around 60-65mm wide and 40-42mm tall frames usually at the widest end with distances of 1-3 cm from the subject. As compact camera sensors are small strictly speaking there are no compact cameras on the market that can capture an object as small as their sensor.
So as far as we are concerned all that matters is that the height of the frame is same or smaller than 24mm as if we were shooting with a full frame DSLR.
For an SLR user the choice of a close up lens is quite straightforward as usually there will be a 100mm lens behind a flat port. This lens gives a magnification of 1:1 usually with a closest focus distance of 12” or 30cm. To achieve more with the same lens there is the need of a close up lens that works with a similar principle of a magnifying glass.
A close up lens will have a determined focal length or maximum working distance, beyond which it will not focus. If you hold a close up lens at the focus distance and look inside it you will notice that the object will appear larger as you step back from the lens and smaller as you get closer to it. The camera lens behaves in a similar way. Once you reach the working distance of the close up lens is the zoom that moves the lens forward or back and effectively provides the magnification. The close up lens only shorten the working distance allowing you to get closer.
Close up lens are measured in diopters this is the ratio between 100cm and the lens focal length. So a lens with a focal length of 20cm is a +5 diopter. A 100mm lens at 30cm once placed at 20cm from the object would achieve a 1.5:1 magnification. So with a 100mm lens in a flat port and a +5 diopter we are able to capture images larger than life-size with a DSLR full sensor. A +10 diopter would give a magnification of 2.1:1.
So how much power do we need to shoot macro with a compact camera? Is it the same than with a DSLR? Are there other considerations that apply?
The first issue is that because compact camera have fixed lens there is no way to predict at a given focal length if we will achieve macro or not. A compact camera zoomed to 100mm equivalent is not the same as a full sensor camera with a 100mm lens: in most cases the capture area is much larger. In fact there is no way to know if our lens will or not achieve our objective of taking a macro shot just looking at the camera specs. To make matters more complicated it is not always possible to get too close to our subject, this may be because there is no physical way to get closer or because we do not want to freak out the marine life that we want to capture. In general I like to leave some breathing space to subjects, as a minimum 3 inches or 7.5cm are needed and a bit more. This means that more than a lens with more than 12 power is generally a bit too close to the subject.
So how do we work out what diopters we need for our lens? Unfortunately we will only know after we have actually tested it, this is of course not very good!
Another possible approach is to define what is the working distance that we can realistically sustain with our equipment and the conditions we dive in.
Generally it is always possible to get between 20cm and 10cm and in some cases also under 10cm. This corresponds to 5 – 10 diopters and sometimes more for example 12. Considering that plenty of marine life is actually one inch or larger to capture a frame where the subject is filling it we do not actually need real life-size macro. In practical terms this means that for a compact with zoom of 100mm a lens with 6 diopters is fine with less or more depending on the camera zoom and focus ability. So for general purpose a close up lens between 5 and 7 is perfectly fine, this corresponds to working distances between 14 and 20 cm or a bit less from the back of the close up lens so actually closer from the front of the lens itself. For very small subjects around 1.5 cm like a pygmy seahorse we would be looking at 10 to 12 diopters, more is impossible as we would be crashing into the critter. This means a working distance between 8 and 10 cm or 3 to 4 inches from the front of the lens or 3 to 5 cm or 1 to 2 inches from the close-up lens that would still allow a small space for our lights.
Will we achieve real life size macro with this? It depends, to give some context my Panasonic LX7 that only has a 90mm zoom will capture a 32mm tall frame with 6 diopters power, strictly speaking this is not macro, and 20mm with two stacked 6 lenses achieving a 1,2:1 super-macro.
There are also other consideration that apply, if all we have is a +10 diopter we need to get very close to our subjects for our lens to start working, in all those situation where we cannot get close we would run into problems. If we look at a videographer with a 10x 400mm zoom camcorder they most likely only need a 2-3 diopter because with the range of zoom available they can comfortably achieve macro staying over a foot away from the subject. So the advice is to always have a 5-6 lens for general work and another 10-12 for smaller subject or if the lenses are stack-able two 5-6 this will cover all possible situations with a camera with a 90-140mm equivalent zoom.
I thought of concluding this blog with some recommendations so those are my recommended close up lenses based on personal use or looking at pictures of others:
DSLR: Reefnet Subsee both 5 and 10 with 100mm lens on full frame or 60mm on 1.5x cropped sensor. The new Inon UCL100 is also worth checking but it is more expensive.
Note that the Inon UCL165 focal length of 165mm is from the back of the lens so the power is 6.06. Dyron lens are reported as 7 diopters however they are then declared 165mm underwater which is actually 6.06 exactly as the Inon.
Optical quality of both lenses is similar so I guess it depends on price what would be the choice. Inon is available with bayonet mount that maybe a big advantage for some cameras like the Sony RX100.
Whilst the Subsee give the best optical quality they are bulky and not flexible so I would not consider those for a compact rig. Inon and Dyron are lighter and more portable and can be stacked, a single diopter will be in most cases sufficient for good close up work with two required only for the smallest critters. It has also to be considered that at least for stills chromatic aberration can be removed in the editing phase, not so for video, but there generally goes unnoticed unless is really heavy. The Dyron and Inon lenses have the level of quality that the aberration cannot be noticed. This muck diving video has plenty of macro and close up with diopters note that no chromatic aberration is visible, shot with single or double Inon UCL165
There are other brands like FIT or époque but there seems to be quite some confusion as their specs are either air values or magnification that as we appreciate depends on the lens used. From tests I have seen the FIT 16 seems less powerful than an Inon 6 and same of a Subsee 5 and they are expensive so not an option for me.
What other tips are useful for shooting with close up lenses? The first is to make sure to use small apertures to have the maximum depth of field.
Contrary to what many believe the diopter itself does not create an issue of shallow depth of field is the size of the subject and the magnification that create the problem. With diopters most times we are at the maximum possible magnification with a total depth of field of few millimeters, it is important to operate at aperture values for a compact camera of f/8 and if available smaller.
For pictures is it also advised to use very fast shutter speed to avoid motion blur that the shake of the camera could create, usually 1/250 or faster unless using a tripod or a solid base. Video is not usually shot with high shutter speed, if available use double frame rate and shutter of 1/100 or 1/125 depending on the PAL or NTSC video system. This will allow half speed slow motion in editing that could prove useful.
Lights are also very important for close up, for still cameras they allow the camera to focus and for video they are needed to actually take the shot. For still cameras a strobe is essential, as video lights do not perform well at high shutter speed.
A final advice is to use the lowest ISO or gain available to ensure the quality of the picture or footage is the best possible, as we are close and have lights this should not be an issue at all. Most macro stills are shot in manual, for video if a manual mode is not available pumping the lights up results in the camera closing the aperture and reducing the ISO. If manual mode is available it is possible to set shutter, aperture and ISO and then measure the exposure that the light give until a satisfactory value is achieved.