Tag Archives: Panasonic GH5

Fisheye Zoom for Micro Four Thirds

Looking at Nauticam port chart the only option for a fisheye zoom is to combine the Panasonic PZ 14-42 with a fisheye add on lens. This is a solution that is not that popular due to low optical quality.

So micro four thirds users have been left with a prime fisheye lens from Panasonic or Olympus…until now!

Looking at Nauticam port chart we can see that there is an option to use the Speedbooster Metabones adapter and with this you convert your MFT camera to a 1.42x crop allowing you to use Canon EF-M lenses for cropped sensor including the Tokina 10-17mm fisheye. This is certainly an option and can be combined with a Kenko 1.4x teleconverter giving you a range of 14.2 to 33.8 mm in full frame equivalent or 7.1 to 16.9 mm in MFT terms fisheye zoom of which the usable range is 8 -16.9 mm after removing vignetting.

A further issue is that the Speedbooster gives you another stop of light limiting the aperture to f/16 while this is generally a bonus for land shooting in low light underwater we want to use all apertures all the way to f/22 for sunbursts even if this means diffraction problems.

Wolfgang Shreibmayer started a trend time ago in WetPixel https://wetpixel.com/forums/index.php?/topic/61629-canon-ef-lenses-on-mft-cameras/ to use full frame lenses and in this post I want to do a deep dive on what is for me the most interesting lens option the Canon 8-15mm fisheye.

This lens on full frame can be used for a circular and diagonal fisheye but Wolfgang has devised a method to use it as an 8-15mm fisheye zoom on MFT.

Part list – missing the zoom gear

What you need are the following:

  • Canon EF 8-15mm f/4L fisheye USM
  • Metabones Smart Adapter MB_EF_m43_BT2 or Viltrox EF-M1 Adapter
  • A 3D printed gear extension ring
  • Nauticam C-815Z zoom gear
  • Nauticam 36064 N85 to N120 34.7mm port adapter with knob
  • Nauticam 21130 30mm extension ring with lock
  • Nauticam 18810 N120 140mm optical glass fisheye port

The assembly is quite complicated as the lens won’t fit through the N85 port. It starts with inserting the camera with no lens in the housing.

GH5 body only assembly
Camera in housing without port

The next step is to fit the port adapter

Attach N85 N120 Metabones adapter

Then we need to prepare the lens with the smart adapter once removed the tripod mount part.

Canon 8-15 on Metabones Smart Adapter IV

As the port is designed for the speed booster the lens will be few mm off therefore the gear will not grip. Wolfgang has devised a simple adapter to make it work.

gear extension ring
Zoom gear on lens

This shifts the gear backwards allowing to grip on the knob.

3D design is here

Lens inserted on housing

Looking at nauticam port chart an extension ring of 30mm is recommended for the speedbooster and now we have extra 5mm in length Wolfgang uses a 35mm extension however looking at the lens entrance pupil I have concluded that 30mm will be actually better positioned. Nauticam have confirmed there won’t be performance differences. You need to secure the ring on the dome before final assembly.

Fisheye dome and extension
Full assembly top view
Side front view

The rig looks bigger than the 4.33 dome but the size of the GH5 housing is quite proportionate. It will look bigger on a traditional small size non clam style housing.

The disassembly will be made again in 3 steps.

Disassembly

I am not particularly interested in the 1.4x teleconverter version consider that once zoomed in to 15mm the lens is horizontally narrower than a 12mm native lens so there is no requirement for the teleconverter at all.

This table gives you an idea of the working range compared to a rectilinear lens along the horizontal axis as diagonal is not a fair comparison. The lens is very effective at 8-10mm where any rectilinear would do bad then overlaps with an 8-18mm lens. The choice of lens would be dictated by the need to have or not straight lines. The range from 13mm is particularly useful for sharks and fish that do not come that close.

Focal lengthHorizontalVerticalDiagonalHorizontal Linear EqWidthHeightDiagonal
8130.995.9170.217.31321.64
9114.984.7147.8
10102.575.9131.06.9
1192.668.7117.88.3
1284.562.9107.29.5
1377.757.998.410.8
1472.053.790.911.9
1567.050.184.613.0

Wolfgang has provided me with some shots that illustrate how versatile is this set up.

8mm end surface shot
Caves 8mm
15mm end close up
Dolphins at 15mm
Diver close up at 8mm
Snell windows 8mm
Robust ghost pipefish @15mm

As you can see you can even shoot a robust ghost pipefish!

The contrast of the glass dome is great and the optical quality is excellent. On my GH5 body there is uncorrected chromatic aberration that you can remove in one click. Furthermore lens profiles are available to de-fish images and make them rectilinear should you want to do so.

I would like to thank Wolfgang for being available for questions for providing the 3D print and the images that are featured here on this post.

If you can’t print 3D and need an adapter ring I can sell you one for £7 plus shipping contact me for arrangements.

Amazon links UK

Canon EF 8-15 mm f/4 fisheye USM lens

Viltrox EF-M1 Mount Adapter

Note: it is possible to use a Metabones Speed Booster Ultra in combination with a Tokina 10-17mm zoom fisheye and a smaller 4.33″ acrylic dome.

UK Cost of the canon option: £3,076

Uk Cost of the Tokina option: £2,111

However if you add the glass dome back

UK Cost of Tokina with glass dome: £2,615

The gap is £461 and if you go for a Vitrox adapter (would not recommend for the speedbooster) the difference on a comparable basis is £176 which for me does not make sense as the Canon optics are far superior.

So I would say either Tokina in acrylic for the cost conscious or Canon in glass for those looking for the ultimate optical quality.

Using Rectilinear Wide Lenses Underwater

I was checking the technical details of Alex Mustard Underwater Photography Master Class and the majority of wide angle pictures are taken with a fisheye lens. In the section about shooting sharks Alex says that he prefers to shoot sharks with a fisheye otherwise they look ‘skinny’.

If you look online on underwater video forums you frequently see comments on problems with wide angle lenses connected with the use of a rectilinear wide angle lens in a dome.

The two most common complaints are soft corners and distortion.

Soft corners are due to a combination of lens optical issues and dome port optics. In short any lens is to some extent curved and therefore if you shoot a flat surface the image may be sharp in the centre and softer as you move to the corners. Issues with field of curvature are corrected stopping down the lens. The issue with field of curvature happens everywhere not just underwater.

Right now there are four wide angle lens that can be housed for a micro four third camera:

Olympus 9-18mm

This lens has a nice working range that allows to capture 100 degrees diagonal at widest setting and still has a 35mm equivalent at the tele end. This is a pretty little lens at $699 is the most affordable option that can be put in a housing. You will need a wide angle port and the zoom gear. The whole combination for your Nauticam housing comes at $1,399. This lens can also be combined with a glass dome but this will make the whole combination much more expensive and you may want to think about getting a better lens instead.

Olympus 7-14mm

This is an outstanding lens especially on land due to the fast f/2.8 aperture. It is expensive at $1,299.99 and very heavy and bulky. The lens does not fit through the N85 port opening and requires a port adapter this gives the extra benefit of a focus know but with such a wide lens is not really useful due to high depth of field. You will need a 180mm glass dome and the zoom gear for the lens to complete the set up ending at a whopping $3159.99.

Panasonic 7-14mm

I have owned this lens and I have to say that at $799 is the right compromise between wide field of view and price. Furthermore once you get the zoom gear you have the option of a cost effective acrylic dome that will give you a very wide set up for $1589.99. There are reports of poor performance with this lens and it is true that is not as sharp in corners but the results are perfectly acceptable if you stop at f/8 in close shots.

Steering Wheel Truck
Panasonic 7-14mm with acrylic dome 9mm f/8
Exploring the Chrisoula
Panasonic 7-14mm with acrylic dome 7mm f/5

This lens is prone to reflections and flare however once you add the N120 port adapter and the 180mm glass dome this will get you to $2819 at that point you may want to consider the Olympus combination instead.

Panasonic Leica 8-18mm

This is my favourite lens is sharp does not suffer from field of curvature issues and has a very useful zoom range 16-35mm in 35mm equivalent. The zoom gear and the 7″ acrylic dome will take you to 1889.99 that is an excellent price point. The lens is not prone to reflection or flare and as the 7″ dome has the same curvature radius than the 180mm dome it will produce very similar results.

Encircled
Panasonic 8-18mm in 7 acrylic dome f/8
Sunset Neat
Panasonic 8-18mm at 8mm f/10

The significant size of the acrylic port and the fact it floats make it ideal for split shots and this is the lens that gives me the best results.

This lens can also take port adapter that allows you to use the 180mm glass dome. This adds up to $2919.99 if you experience bad reflections and shoot frequently in the sun it may be worth it but I have not had any issue so far with this lens probably because of its nano coating.

I have found the 7mm focal length too problematic for dome ports and the amount of perspective distortion excessive generally it would be preferred to shoot at 9mm and narrower however this maybe insufficient for wreck interiors if you want a rectilinear look.

Perspective Distortion

One of the regular complaints of video shooters especially in wrecks or caves is that the edges look horrible and distorted and that there is an issue with the corners pulling. This is in fact not an issue but a problem with perspective as you shoot very wide angle. The following test shots will illustrate that the issue happens on land and has nothing to do with dome ports.

Shot at f/2.8 with Panasonic 8-18mm at 8mm shows sharp corners
Image with objects in edges at 8mm

As we can see the football looks like an oval and the chair is pulled. This is due to a perspective issue and is not a lens problem. When you shoot underwater video the objects on the edges of the frame change shape creating this pull effect that most people dislike.

Same scene at 9mm

At 9mm the amount of perspective distortion is reduced and this is the reason why 18mm on 35mm equivalent is one of the favourite focal length for rectilinear video and the maximum angle that should be used in small spaces to avoid the pulling edges.

One of the reason why a lens like the Nauticam WWL-1 is preferred for video is because the corners look sharp but is that really true?

Not really let’s apply some barrel distortion to simulate the WWL-1 to the image that looked badly distorted.

Barrel distortion applied -60 8mm

Now the football looks circular as we have applied -60 barrel distortion, obviously the rest of the image is now bent but this seems not to be of a concern to most people!

Barrel distortion -30 9mm

It needs much less correction to bring the 9mm shot into shape and for sure between the 8mm and 9mm the 9mm is the dimension that produces the most acceptable results.

It has to be said that in video with 16:9 aspect ratio most of the issue will be cropped away at the edges but the distortion in the middle of the frame will remain. For the same reason the 9mm image will appear practically rectilinear with no issues

16:9 crop still showing the edge ‘pulling’ at 8mm

16:9 crop looks straight at 9mm

I hope this post was useful there are four options for micro four thirds shooters to use rectilinear lenses I have settled for the Panasonic 8-18mm as in most cases it is still possible to control the perspective issue, I found this impossible at 7mm.

Bike on Hold 2
Bike in hold 2 on SS Thistlegorm Panasonic 8-18 at 8mm
Bubbling Bike
Shot at 7mm showing the front tyre pulling outside the frame

Obviously if you shoot in the blue this problem will not be visible however rectilinear lenses are popular with wreck shooters and I think this posts gives an idea of the challenges at play.

Finally I would discourage the use of the 7-8mm focal length range for video to those that want to have a rectilinear look.

From this post I started supporting Bluewater Photo in US for my links because it still provides multi brand and choice and because I learnt a lot from Scott Gietler Underwater photography guide back in the days where there was no internet resource to learn from.

The importance of Underwater white balance with the Panasonic gh5

One of the key steps in order to get the best underwater colours in your video is to perform a custom white balance.

This is true on land and on water because auto white balance only works in a specified range of color temperatures.

Panasonic GH5 advanced user manual

For our GH5 the range where auto works goes is approximately 3200-7500K. When the camera is working outside this range you get a colour cast. Let’s see with some examples:

Grey card Auto White Balance 8mm
Grey card Custom White Balance 8mm

In the example above I am taking a picture of a white balance reference card under warm lights that have a colour temperature of 2700K.

As you can see the auto white balance fails resulting in a yellowish tinge, while the shots taken after the custom white balance is accurate.

In terms of white balance card I use the Whibal G7 Studio 3.5″x6″ (8.9×15.2 cm). I found this card to work well underwater and I use it with a lanyard attached to a clip that I hook on my BCD D rings.

More info on the whibal here

It is possible to buy a larger card such as the reference that is 7.5″x10″ however this is cumbersome and I found the Studio version to work well with the Panasonic GH5 as it only uses the central part of the frame for white balance.

Custom white balance with the 8mm fisheye

Going back to our GH5 instruction manual you can also see that the camera white balance is limited to 10,000K which is the colour of blue sky.

Underwater due to light absorption at longer wavelengths red and orange disappear at depth and blue tends to scatter over suspended particles. So the colour temperature of water tends to be higher than 10,000K and also the blue is somewhat washed out by scattering.

This is the reason filters are essential because reduce the amount of blue or to say better cyan and bring the camera into a range where custom white balance works again.

I have already posted a whole range of observations on filters in a previous post so am not repeating here.

With the right filter for the water colour I dive in and with the appropriate white balance card you can get some pretty decent results with custom white balance.

To help the colour accuracy I have experimented with the Leeming Luts and I want to thank Paul Leeming for answering my obscure questions. Obviously you do not have to use the LUTs and you can design them yourself however I found that using the Cinelike D LUT I have a very good starting point for colour correction.

The starting point is a CineLike D profile with saturation, noise reduction and sharpness set to -5 all other settings to default as suggested by Paul, there is no need to lower the contrast as CineLike D is already a flat curve.

*Noise and sharpness have actually nothing to do with grading but are set to -5 as the GH5 applies sharpening and noise reduction even at -5 setting. Sharpening has generally a negative effect all around while noise reduction if required is better performed in the editor.

Looking at imaging resource tests of the GH5 we can appreciate that the camera colours are oversaturated by default.

the GH5 has around 113% over saturated colours

The GH5 tends to push deep colour and wash out cyan and yellow. This becomes apparent when we look at a white balanced clip uncorrected.

White balanced clip in final cut pro you can see how the water column is washed out whilst red and other dark colours are accurate

The Leeming Lut helps rebalancing the camera distorted colours and when you apply the camera LUT, provided you have followed the exposure instructions and applied the profile as described, the improvement is immediate.

The previous clip now with the CineLike D Leeming LUT applied

From here onwards it is possible to perform a better grading and work to improve the footage further.

For the whole read please look at Leeming Lut website

One other thing that I believe it is interesting is that while generally for ambient light or balanced light shots I do not actually trust the camera exposure and go -1/3 to -2/3 for close up shots exposing to the right greatly helps highlights recovery

In the two frames you can see the difference the LUT brings restoring the correct balance to the head of the turtle.

Turte detail the highlights appear blown out
Turtle detail with Leeming Lut applied

To be clear the turtle detail has been white balanced in water on the whibal card while using a Keldan Spectrum filter -2, then in fcpx automatic balancing is applied. The LUT brings out a better dynamic range from the same frames.

Obviously you are free to avoid lens filters and LUTs and to some extent it is possible to get similar results however the quality I obtain using automatic settings I believe is quite impressive.

I found myself most times correcting my own wrong exposures or wanting to increase contrast in scene where I had little however this only happens in sever circumstances where white balance and filters are at the limits.

Conclusion

There are many paths to get the right colours for your GH5 underwater videos in my opinion there are four essential ingredients to make your life easier and give your footage a jump start:

  • Take a custom white balance using a professional grade white balance card
  • Set the right picture profile and exposure when shooting
  • (Recommended) Use appropriate filters for the water conditions
  • Apply the appropriate LUT to eliminate the errors in the GH5 colour rendering in post processing

With the following settings producing a video like this is very simple and all your efforts are in the actual cutting of the clip.

Short clip that applies this blog tips

Please note some of the scenes that look off are shot beyond the working conditions of filters and white balance at around 25 meters…

which macro lens to pick for your gh5 or micro four third

I see many posts on line debating which macro lens is best for your micro four third system.

If I refer to the Nauticam system we have 4 macro lenses:

  • Olympus 30mm
  • Panasonic 30mm
  • Panasonic 45mm
  • Olympus 60mm

For the purpose of this article I will skip the Olympus 30mm as the Panasonic lens is known to be sharper and will focus on the other 3 lenses.

DxOMark is a popular tool for comparison as it gives you the results on one page. I have run it for the Oly 60 and the Pana 30 and 45 on the 20 Mpix OMD E-M1 MKII

DxOMark Comparison on Olympus OMD E-M1 MKII

Surprisingly the much more expensive Leica performs worse than the other cheaper models, this is confirmed on all internet sites running other type of tests.

What we can see is that there is little difference between the Panasonic 30mm and Olympus 60mm when it comes to image quality so whichever lens you choose your subject at the same level of magnification and aperture will have more or less the same detail.

Common Misconception: Shorter focal length give more depth of field

Many people think that using a longer lens is harder because there is less depth of field this is actually incorrect conceptually.

Let see why

Using an online calculatore like Dofmaster https://www.dofmaster.com/dofjs.html

Enter for the Panasonic GH5 the following parameters

Circle of confusion: 0.015 mm

Focal length 30mm

Distance 10.5 cm (minimum distance of the 30mm Macro)

Aperture f/11

Result Total depth of field 0.3cm

Now enter

Focal Length 60mm

Distance 21 cm (as it achieves the same magnification)

Aperture f/11

Result Total depth of field 0.3cm

So depth of field is not a consideration when choosing a macro lens…

Shooting a subject close to the background

In the following 3 shots am taking an image of a widget at f/11 at 29-44-60 mm on a Leica 12-60 (it is just easier it makes no difference to the outcomes)

Shot at 60mm
Shot at 44mm
Shot at 29mm

At the same aperture you can clearly see that there are no difference whatsoever in the detail and actually overall in the picture you don’t notice anything.

Shooting a subject far from the background

For the second shot I have moved the widget away from the wall.

Shot at 60mm
Shot at 44mm
Shot at 29mm

Again there is no difference in the level of detail of the widget however looking at the background we can see that

  • The 60mm shot reveals one brick and less than one quarter
  • The 44mm shot reveals one brick and a half
  • The 29mm shot reveals two bricks

So while the subject is exactly the same as the 60mm lens has a narrower field of view we see much less of the background.

This means that if you are shooting a nudibranch on the sand or something flat on a rock you won’t notice anything however if there is space behind the subject you will capture much more of that resulting in less subject isolation.

Underwater Comparison 30 vs 60 mm

In the first shot the Rhinopia is taken with a 60mm lens

Rhinopia Olympus 60mm

In the second shot the same Rhinopia with the 30mm (in a different place to be fair)

I have marked up with red the areas that with a longer focal length would have been minimised.

Which Lens to choose?

Now that we have clarified that depth of field is not a consideration and as each macro lens will have the same magnification there are only two factors that matter:

  1. Working distance
  2. Isolation from background

The 60 mm will have a longer working distance and at the same magnification will isolate the subject better from busy backgrounds, the 60 mm is also better for skittish subject because of the longer working distance. I have this lens and I have borrowed the 30mm in couple of occasions but do not have the 30mm yet.

There are however situations where longer working distance is not a benefit, specifically when the visibility is poor and there are suspended particles or the subject is really large.

In the example below I was at one meter from the two frogfish, a 30mm would have been better however the shot came OK.

Hairy frogfish Olympus 60mm

Conclusion

I believe the Olympus 60mm is a must lens to have. To date I have not felt the need for the Panasonic 30mm that is indeed a very sharp lens because I have always managed to pull out the shots. However for someone diving in murky water and focussing on nudibranches or subject laying flat on the seabed the Panasonic 30mm could be a better choice. I also want to say that using the 14-42mm at 42mm for me is actually a better choice for portraits and with a close up lens works very well with small subject not super macro and therefore as I already own the 14-42mm and various diopter for me the 30mm is not on the shopping list.

Getting the best colors in your underwater video with the panasonic gh5

There is no doubt that the Panasonic GH5 is a very capable camera and in given conditions the video performance you can get is truly impressive.

Broadly speaking a video clip needs to be:

  1. Sharp
  2. Colorful
  3. Contrasty
  4. Clean

Those 4 characteristics are tightly related to:

  1. Resolution
  2. Color depth
  3. Dynamic range
  4. Low Noise

Resolution

Today everyone shoots 4K and after all resolution is well supported by almost any camera, broadly is unaffected by other factors and unless the noise is really high sharpness of your frame is not going to be a real issue shooting at 4K.

Color depth

In normal conditions and not underwater a camera can resolve many colors. However underwater due to the diffraction of light and selective absorption of colours the starting point is very different from land. So generally is not the camera that cannot resolve the colors but the colors that are missing to start with. This post will focus specifically on this aspect. The Panasonic GH5 can resolve 23.8 bits in RAW and therefore technically has less than 8 bits color depth – do not confuse this with the 8 or 10 bit recording setting.

Dynamic Range

Underwater scenes tend to have limited dynamic range, with the exception of sunbursts or shooting against the light this is going to be an issue only in specific circumstances of very bright scenes with shadows. In all scenes taken with video lights dynamic range is not an issue at all. The GH5 has 13 stops of dynamic range but rarely this is an important consideration.

Noise

Noise is an important consideration as when the noise goes up the camera looses the other characteristics, color, dynamic range and resolution will be affected when the camera is outside the sweet spot. Broadly speaking the Panasonic GH5 does not do well once you pass the ISO 1600 setting and I tend to cap the ISO in video at 800 in most cases.

Diving Conditions

To understand how those variables play we can see how the same set up reacts very differently in scene where there is less light and therefore the camera uses high ISO like this one.

The same camera with exactly the same equipment in brighter water produces this

So the reason for the above is that with less light there are less colours and the clip looks what it is really.

OK moving on to the main subject of this post how do I get the colors right? It is a combination of techniques and the trick is to use the right one in the right conditions.

Generally every site has specific conditions that change depending on weather, time of the day, visibility and other factors. So in broad terms a site will have more or less light and therefore more or less colours. It is therefore impossible to categorically define what to do at a given depth but is more about typical values. With this in mind we have typically 3 scenarios:

  1. Ambient light shots
  2. Artificial light shots
  3. Balanced light shots

Close up Shots

In general close up shots especially of small subject fall within the scenario 2 for which a video light with high color rendering is important as this will define the colours you see. With a lot of power it is possible to extend artificial lighting to larger subjects but eventually you run out of power due to distance or size of the subject.

Wide angle shots and seascapes

True wide angle shots are generally ambient light shots which also means when it gets too dark the colors will be missing and it will look blue not matter the equipment.

In order to make the most of ambient light shots for wide angle it is essential to balance the colours in water even when you use a RAW format on a still image because RAW files are not as RAW as you think and are actually compressed.

Custom White Balance

Using Custom White balance with a grey card it is possible to obtain decent results until the camera hits the maximum color temperature in the case of the Panasonic GH5 this is 9900K. Depending on conditions you may get to 10-12 meters and this still works, in darker water this stops working much sooner.

Chrisoula K Bow
Chrisoula K Ambient Light 5 meters

Color Filters

Color filters push the limit of custom white balance further down. Some add more or less 4 meters others up to 6-8 meters at the expense of an overall loss of light. Filters are useful when there is a lot of light because also help to keep the Panasonic Gh5 in the best aperture range (not smaller than f/11)

Filter in action at 10 meters

Right now there are predominantly 3 filters on the market:

  1. UR PRO
  2. Magic filter
  3. Keldan Spectrum

All those filters will improve the performance and color rendering of your footage, under the conditions that the loss of light is not pushing the camera above reasonable ISO values.

In terms of depth range the magic filter and the Keldan Spectrum -2 version can be pushed to 15 meters depth on a bright day in clear water. The URPRO is capable of getting a few meters more down to around 17-18 meters although it does generate an orange cast (as there is no red left) it is still workable.

FilterLight LossTypical Max Depth
Magic Filter1 2/3 Ev15 meters
Keldan Spectrum -22 stop (WWL)12 meters
URPRO 1 2/3 Ev18 meters

This image gives an idea of the 3 filters as you can see they are very different one from the other.

Keldan top URPRO bottom Magic filter

Balanced Wide Angle Shots

This is an entirely new technique that has started with the Keldan Ambient light filters. I wrote a whole piece on wetpixel

The principle is to use custom white balance with or without filter to obtain color rendering and then put filters on the video light so that the color of the light emulates the ambient light and therefore it only gives texture not color.

Keldan has developed a whole range of filters for various situation that match their light and therefore are not applicable to any other light.

As I do not own a set of Keldan I have done some tests and found that a gel of Cyan filter 2 or 3 stops makes my divepro G18+ practically ambient light in the conditions I dive into.

FilterCyan Strength
Magic Filter2 stops
Keldan Spectrum1 1/2 stops
URPRO3 stops

The above value are based on my experience use at your own risk especially with different lights.

Square Cyan 2 stops Round Cyan 3 stops

To give an idea I overlapped the filter to my iPhone lens

This is the shot without any filters

Original Shot

URPRO and Cyan 3 stops (darker)
Magic filter and cyan 2 stops accurate
Keldan and cyan 2 stops accurate

This example shows that the two filters cancel themselves the result is almost daylight with no cast which means in water if you use a video light or a strobe you will not see a red or orange spots on the image.

For those taking pictures the same combination remains true with Inon Z240 and Sea and Sea YS-D2

Example picture here

five in a row
My own filter and Cyan 3 stop note that the light is coming from the other side

One thing to take into account is that you need to find a way to hold the gel on the video light or the strobes. The flat surface strobe diffusers make this process easy, finding something you can use with your video lights is not easy and also the gels may melt after continuous use.

Artificial lights

It comes a point and a depth where filters stop working, this could be as shallow as 8 meters in green water. As the scene is dark using lights is what is required. There is nothing specific about this technique except making sure you don’t get burned highlights or backscatter. As it happens in photography using long arms (maybe not as long as for stills) is key to get good lighting on your subject.

My Camera Settings

I use CineLike D with saturation, sharpness and noise reduction to -5. I shoot at 24/25p AVCI 400 mbps and follow the 180 rules, it is entirely possible to shoot at 1/100 if you like more crisp look.

Clearly there are people out there that do not like filters and think white balance is best etc but I think a good read on magic filters explains it all.

http://www.magic-filters.com/need.html

Macro video with the Panasonic gh5

Broadly speaking with the GH5 as well as with any other camera you have four categories of close up work:

  1. Close-up – frame size 10 cm or 4″ and wider typically hand held
  2. Super close-up – frame size 5cm or 2″ preferably on tripod
  3. Macro – frame size below 2″ only on tripod
  4. Super macro – frame size below 1″

For still images a typical choice is the Olympus 60mm, this lens however is very narrow so for any subject that is not too small and for the first category of close up you end up having working distances well above one foot. This in turns means more water to go through and makes it virtually impossible to cover larger subjects.

If you make that choice is because you have skittish subjects that do not like proximity and are very small. Furthermore the Olympus 60mm has not stabilisation and therefore with our GH5 will only use in-body stabilisation. Another side effect of using this lens is that it is impossible to take shots of divers or anything else at medium range so the videos end up being a collection of very close shots that may please someone but result fairly boring.

Of course you can make this kind of video exciting to an extent like here

But at the end for me something like this is more fun although of course the quality is very different (I shot this years ago with a Panasonic LX7 and edited in iMovie)

The difference between the stunning video of Dustin and the basic video of mine is that you only have very close shots in the first one and frankly a slideshow of still images would be equally nice. There is no description of any sort of where is the fish what are the conditions or anything at all. You may argue that the stuff to see is not that nice but at the end this gives you a real idea of the diving where you go which is the purpose of my videos and majority of non Pro people. Furthermore medium size subjects that move like octopus, squids, crabs will almost always exhibit some kind of behaviour.

My macro video rig is built around the Panasonic 14-42 MKII which is the same lens I use for wide angle video with the Nauticam WWL-1. In effect am running video like a compact set up.

GH5 Macro Video Rig as at 29 March 2019

Ergonomics and lens

  1. The field of view with at 42mm is only 23 degrees horizontal and 13 degrees height this is ideal for portrait type of work
  2. I still use my old Sola 1200 video lights that can be used with a 20 degree beam creating a snoot like effect to better isolate your subject. It can be argued that color rendering index of newer lights is better but I think the narrow coverage of the lights is more important. Consider that at wide end the field of view is less than 60 degrees anyway with the flat port at 18mm
  3. I use two close-up lenses with a Saga dual flip diopter
  4. The rig as described is heavy in water more than 700 grams negative to ensure the required stability
  5. The tripod base has 2x 3″ segments and 1x 5″ segment to be as close as possible to the bottom this creates issue if you do not have a monitor as you need to have your face in the sand however once the shot is framed all is good

Close-up lenses

I use two close up lenses with this rig as the 14-42mm as a working distance in water around 26cm and a minimum frame size around 9cm that is pretty wide.

SubSee 5 wet lens

The SubSee 5 is in the sweet spot for the 14-42mm lens because it starts working pretty much when the 14-42mm can-t focus anymore and down to around 10-12 cm working distance. Minimum frame size is 46 mm

SubSee 5 + 14-42@42mm

Using the Ex-Tele feature in video means we can get to 33mm which is below the 36mm classic DSLR 1:1

When this is insufficient and the subjects are really tiny the next lens is the Nauticam CMC-2

Nauticam CMC-2 on Saga dual flip holder

The CMC-2 gives a frame size of 32mm as in this image

Panasonic 14-42@42mm with CMC-2

Using Ex-tele this becomes 23mm which is the same you get with the CMC-1 without ex-tele and is plenty for any purpose. It is theoretically possible to stack the two close up lenses but is not really necessary and the working distance too small. The CMC-2 works around 6-7 cm so you have still space for lights etc.

Olympus 60mm

Is there any use for this lens? Of course there is in case you want to capture a frame smaller than 23mm with the 60mm you can get down to 17mm with the bare lens to 12mm with the Ex tele, 9 mm with the CMC-1 and 6 mm with CMC-1 and ex tele. Will you be able to focus and work with the CMC-2 at 22mm from the subject is another discussion however for skittish subjects it gives you more working distance and this may be needed. I would recommend taking this lens with you for those cases but for video I do not see how you can really use the CMC-1. Please note the CMC-2 is useless with the 60mm as the working distance improvement is minimal to none.

PANASONIC GH5 my underwater still rigs

The Panasonic GH5 is well known to be a great camera for video and I can confirm that see my latest videos

Clearly the camera is fantastic and with the right set up that I will cover in future posts it takes amazing video.

I wanted to start however from photography as the GH5 also takes great still images.

First and foremost macro. In general terms the lens choice of other micro four third also applies to the GH5 so my favourite lens is the Olympus 60mm. Alternatively if you don’t have that lens and you don’t have extremely small subjects you can get good results with a zoom lens I use the Pana 14/42 MKII but other work well too.

In terms of arms strobes nothing changes so my current rig is based on a Nauticam NA-GH5 housing and two Inon Z240. I have each arm set with 1x 8″ and 1x 5″ arm segments you will notice that the longer arms is closer to the camera this because in macro you will usually shoot above the sand so this makes it easier.

For wide angle the situation changes slightly as I use a 12″ arm segment as in the rig below.

GH5 with WWL-1 wet lens and 8+12 arm segments

For wide angle the arms return to a standard situation with shorter segment close to the housing. The same configuration applies if you shoot the 8mm fisheye.

In terms of floatation the GH5 housing is heavy with the 35 macro port is 720 grams and with the fisheye 620 grams. For macro I like my set up to be negative so less floats . For wide angle in case you take slow shutter speed shots I also use the tripod kit for the NA-GH5 this is not as good as a complete tripod but works well in wrecks

In the next posts I will talk about video as here there is a question about diopters and which ones do I use. Lights is also a topic of contention and will discuss few options there too

As always please ask questions if you wish

Panasonic GH5 Demystifying Movie recording settings

 

There are a lot of videos on YouTube that suggest that there is not much difference among the various recording settings of the GH5 for UHD.

To recap we have 4 settings for UHD (I will refer to PAL system because it is easier but all applies equally to 24p, the 30p/60p format will be the same with worse results)

  1. 100 Mbps 420 8 Bits Long GOP 25p
  2. 150 Mbps 420 8 Bits Long GOP 50p
  3. 150 Mbps 422 10 Bits Long GOP 25p
  4. 400 Mbps 422 10 Bits All-Intra 25p

The difference between Long GOP and All Intra is that in the Long GOP what is encoded is a group of pictures (GOP) and not separate individual pictures. In this article I will use ProRes as a proxy to AVC-Intra as, in the GH5 implementation, they have very similar logic and performance you can find some posts on the internet of people trying to discern the two but there really is not difference as essentially this is just image compression. 

Within a Group of Pictures there are different type of frames:

  • I (Intra coded) frames containing a full picture
  • P (Predictive coded) frames containing  motion interpolated picture based on a prediction from previous frames
  • B (bi-predictive coded) frames containing a prediction from previous or future frames

It is important to note that frames are not stored sequentially in a GOP and therefore the GOP needs to be decoded and the frames reordered to be played, this requires processing power.

The reason why H264 is very efficient is that within a group of picture there is only one full frame and the rest are predictions clearly if the prediction algorithm is accurate the level of perceived quality of long GOP is very high and similar to All-Intra clips.

This is the reason why comparing All Intra and Long Gop using static scenes or scenes with repetitive movement that can be predicted very accurately by the codec is a fundamental error.

Incorrect example here:

The scene is composed of static predictable objects with no motion and after YouTube compression the (wrong) conclusion is that there is no absolute difference between the codecs. Instead what this shows is the effectiveness of Long GOP when the prediction is accurate which is exactly the point of the codec plus the fact that YouTube flattens differences due to heavy compression and use of Long GOP.

Another example is a bit better as it uses a fountain which is a good representation of unpredictable motion

In the 300% crop you can see how All_Intra performs better than Long GOP in terms of prediction despite the YouTube compression, but generally those tests are unreliable if you see the last section of the video where there is a semi-static scene you cannot really take the three examples apart.

So why is that and is there any point selecting different settings on your Panasonic GH5?

In order to understand the workings we need to dig deeper into the structure of the GOP but before doing so let’s evaluate the All-Intra codec.

AVC All-Intra explanation

This codec records at 400 Mbps so with 25 fps this means circa 16 Mbits per frame or  1.9 MB per frame and there is no motion interpolation so each frame is independent from the others. The implementation of All-Intra of the GH5 does not make use of CABAC entropy encoding as Panasonic does not believe this is beneficial at higher bit-rates making this AVC-Intra implementation very close to ProRes as both are based on Discrete Cosine Transform.

If you consider a Jpeg image of your 3840×2160 frame on the GH5 you see that it stores around 4.8 MB per image because there is no chroma sub-sampling so if you wanted to have exactly the same result you would need to use ProRes 4444 to get a comparable quality (this not even taking into account that Jpeg are 8 bits images).

Video uses chroma sub-sampling so only part of the frame contain colours at a given time. Apple in their ProRes white paper declare that both ProRes 422 and 422 HQ are adequate to process 10 bit colour depth and 422 sub-sampling however they show some quality differences and different headroom for editing. If you count 50% for 4.2:0 sub-sampling and 67% for 422 you get around 2.34 MB and 3.5 MB frame sizes that correspond to ProRes 422 and ProRes 422 HQ individual frame sizes.

In simple terms All Intra 400 Mbps would fall short of Apple recommended bit-rate for 422 10 bit colour for circa 92 Mbps is like saying you are missing 0.44 MB from your ProRes 422 frame and 1.6 MB from ProRes 422 HQ and you have 0.3 MB more than ProRes LT however I do not have the full technical details of ProRes to evaluate directly.

The real benefit of such codec is that it can be processed with modest hardware without conversion as the AVC Intra codec is edit ready and each frame is captured individually without any motion artefacts and therefore the computer does not have to do a great deal of work to decode and render the clips.

In order to record All-Intra in your memory card you need a V60 or higher specs card which in terms of $ per GB costs you more than an SSD drive however you no longer need a recorder.

Coming back to the other recording quality option we still need to evaluate how the various long GOP codecs compare relative to each other.

In order to fully understand a codec we need to decompose the GOP into the individual frames and evaluate the information recorded. If you look on Wikipedia it will tell you that P frames are approximately half the size of an I frame and B frame are 25%. I have analysed the Panasonic GH5 clips using ffprobe a component of ffmpeg that tells you what is exactly in each frame to see if this explains some of the people claims that there is no difference between the settings.

Link to Panasonic documentation

 

100 Mbps 420 8 Bits Long Gop 25p Deep Dive

An analysis with ffprobe shows a GOP structure with N=12 and M=3 where N is the length in frames of the group of pictures and M is the distance between I or P frames.

So each Group of Picture is made like this

IBBPBBPBBPBBP before it repeats again.

A size analysis shows that B frames are in average 14% of the I frame and P frames are around 44% of the I frame.

I B B P B B P B B P B B
Size 1648326 247334 237891 728777 231947 228048 721242 228347 227544 713771 236866 232148
Ratio to I frame 100% 15.01% 14.43% 44.21% 14.07% 13.84% 43.76% 13.85% 13.80% 43.30% 14.37% 14.08%

With an average video bit-rate of 94 Mbps each GOP has 45.3 Mbps which means an I Frame has around 13.1 Mbits or 1.57 MB per frame and an equivalent All-Intra bit-rate of approximately 328 Mbps however this codec is using CABAC entropy encoding that Panasonic states is 20-30% more efficient than CAVLC used in All-Intra so net of motion artefacts this codec is pretty strong.

150 Mbps 420 8 Bits Long GOP 50p Deep Dive

An analysis with ffprobe shows a GOP structure with N=24 and M=3 where N is the length in frames of the group of pictures and M is the distance between I or P frames.

So each Group of Pictures is made like this

IBBPBBPBBPBBPBBPBBPBBPBB before it repeats again.

A size analysis shows that B frames are in average 13.4% of the I frame and P frames are around 41% of the I frame. With an average bit-rate of 142.7 Mbps each GOP has 68.5 Mbits which means an I Frame has around 11.3 Mbits or 1.35 MB per frame and an equivalent all Intra bit-rate of approximately 566 Mbps. Again this uses CABAC entropy encoding so the equivalent All-Intra is higher.

One very important aspect of the 150 Mbps codec is that as the GOP is double the length of the single frame rate 100 Mbps codec there are the same number of key frames per second and therefore it is NOT true that this codec is better at predicting motion. In fact it is exactly the same so if you had acquired a 100 Mbps codec at 25 fps and then slowed down the footage to half speed asking your editor to interpolate intermediate frames it would come to the same result although with some more processing required.

150Mbps 422 10 Bits Long Gop 25 fps

An analysis with ffprobe shows a GOP structure with N=12 and M=1 which means this codec does not use B frames but just I and P frames so the GOP structure is as follows:

IPPPPPPPPPPP before it repeats again.

A size analysis shows that P frames are on average 53% of I frames so this codec is in fact less compressed however this has also some consequences.

With an average bitrate of 150 Mbps each GOP has 72 Mbits which means an I Frame has around 10.5 Mbits or 1.25 MB per frame and an equivalent all Intra bitrate of approximately 262 Mbps. So this codec in terms of compression efficiency this is actually the worst and this is due to the lack of B frames.

We can only think that the Panasonic GH5 processing is not strong enough to capture 10 bit and then write 422 Long GOP with IPB structure.

Codec Ranking for Static Image Quality UHD

So in terms of absolute image quality and not taking into account other factors the Panasonic GH5 Movie recording settings ranked by codec quality are as follows:

  1. 400 Mbps 422 10 Bit All intra 25 fps (1.9 MB per frame)
  2. 100 Mbps 420 8 Bit Long Gop 25 fps (1.57 MB per frame)
  3. 150 Mbps 420 8 Bit Long Gop 50 fps (1.35 MB per frame)
  4. 150 Mbps 422 10 Bit Long Gop 25 fps (1.25 MB per frame)

The 100 Mbps  and 400 Mbps codec are marginally different (21% larger frame size) with the 422 10 Bits long GOP really far away.

Conclusion

If you want to record your footage to the internal memory card you are really left with two choices:

  1. Use the 100 Mbps Long Gop codec it is very efficient in the compression and the perceived quality is very good. It does however require you to convert to ProRes or similar during editing if you don’t want to overload your computer as the codec is really heavy on H264 features. You need to get the exposure and white balance right in camera as the clips may not withstand extensive corrections. There is a risk with footage with a lot of motion of some errors in motion interpolation that can generate artefacts.
  2. Buy a V60 or V90 memory card and use 400 All intra at single frame rate. This will give you edit ready footage of higher quality without motion artefacts, You still need to get exposure and white balance right in camera as the headroom is not so large to allow extensive corrections. The bit-rate and frame size is not sufficient to really give you all the benefits of 422 sampling and 10 bit colour but it will be a good stepping stone to produce good quality rec709 420 8 bit footage.

Generally there appears to be no benefit using the internal 422 10 Bit codec nor the 420 8 bit double frame rate due to the limitations of the GOP structure, here Panasonic has created a few options that to be honest appear more a marketing effort than anything else.

There may be some use to the 150 Mbps double frame rate if you intend to slow down the footage after the conversion to ProRes or similar but the extremely long GOP does not make this codec particularly robust to scenes with a lot of motion and in any case not more robust than the 100 Mbps codec.

A final thought if you are interested in 10 bit colour is that the FHD All Intra 200 Mbps codec has enough quality and headroom to allow manipulation. This is in fact the only codec that has bit-rate higher than ProRes HQ at least at 24 and 25 fps so if you want to check the real range of colours and dynamic range the camera is capable of you should try this codec.

Note: I have removed some comments on ProRes and external recorders as there are plenty of people that believe that the intra codec does better than ProRes HQ on the Atomos

Panasonic GH5 the gateway to 4K HDR Video

It has been a while I have been busy with some personal stuff and to be frank not much has been happening the Underwater Video or Still scene that was of interest to me until pretty much September 2017 when Panasonic released the 2.0 version of the DC-GH5 firmware.

The link to the firmware updates is here and here is link to the full PDF

The section we are interested is this one

4K HDR video recording

– [HLG] (Hybrid Log Gamma) is added to [Photo Style]. HDR (High Dynamic Range) is a mode to reproduce both bright part and dark part in an image, making it look just as human eyes see. The camera records video with a designated gamma curve compatible with ITU-R BT.2100, and you can now choose Hybrid Log Gamma (HLG) in [Photo Style].
– A low-bit-rate recording mode 4K HEVC for HLG was added. This enables playback on AV equipment compatible with the HEVC compression format, such as Panasonic 4K HDR TVs.

 

In the PDF we read this additional information

Recording of HDR (High Dynamic Range) motion pictures in HLG (Hybrid Log Gamma) format is now supported. With this format, you can record bright images susceptible to overexposure with more natural colors than is possible with conventional formats.
• “HLG” is a standardized HDR video format that converts and expands the dynamic range of

compressed high-luminance image data on a supported device.
• The monitor and viewfinder of the camera are not capable of displaying images in HLG format. • HDR images appear darker on devices that do not support the HLG format.

If you have headache to understand what is HLG and how it differs from other HDR formats search on the internet the following short document from BBC may help.

 

Why does HDR matter and what can I do to record HDR?

HDR matters because the human eye is more sensible to contrast and colours than resolution. In majority of cases if you do a blind test of UHD 4K footage to anyone sitting at the recommended seating distance for cinema at home (look up SMPTE seating distance) nobody can actually see differences between HD and UHD and this is because the ability of the human eye to resolve pixels is limited by our visual acuity. So why does a YouTube video in 4K looks better than HD? Simply because the bitrate is higher and this means the quality is higher but if you look at your own 4K footage at home and scale it down to HD with good quality you are not able to tell the difference.

However try now some HDR material if you have Amazon or Netflix or even on YouTube and have a compatible Tv set the difference to normal content is staggering. This is because a normal REC709 (the standard for HDTV) display has 6 stops of dynamic range. There are no official figures of how many stops is REC2020 for HDR but good Tv sets are capable of around 10 stops. Now that is a big difference especially on the bright part of the image which is where the HDR displays really excel.

So HDR does matter more than 4K UHD in fact Sony has just produced an HD set HDR capable not sure there will be many of those but this gives an idea.

So how do I record HDR and why there are no HDR certified cameras but only certified displays? The answer is pretty easy you need a camera that offers more than 10 stops dynamic range in video and that is where our Panasonic DC-GH5 comes into the picture.

The camera is capable of 13 stops dynamic range but what is more important it can produce around 8 eV even at ISO 12800 so in essence the camera is well above what is required for REC709 and it can get to around ISO 3200 and still produce nearly 10 stops which is great. So if you have a Panasonic GH5 you have a sensor that is capable of producing the required dynamic range.

However this is not sufficient the camera needs to be able to product at least 10 bit colour depth, an image resolution of 3840×2160 and a colour palette aligned to BT.2020 specifications (wide colour gamut) and finally have the appropriate transfer function to deliver the signal. Majority of commercial cameras are not capable to deliver 10 bit colour depth and do not have a compatible transfer function. The GH4 predecessor of the GH5 was already capable of delivering 10 bit colour to an external recorder using the HDMI output now the GH5 makes this available in camera for recording on SD card at bit rate of 150 mbps IPB and 400 mbps all intra H.264.

HLG vs VLOG and why it matters

Before the firmware 2.0 the only way to produce HDR out of the GH5 was to buy the VLOG upgrade and then attempt to use the recording feature of the camera or an external recorder with Prores 422 or 422 HQ and then take a trip into grading. The reality is that once you crammed the VLOG dynamic range into a REC709 format you essentially limit yourself to 6 stops and therefore waste majority of your effort. So in order to extract real dynamic range you need to output in HDR that is possible but not so easy to do. In practical terms unless you are producing a documentary you will soon give up using vlog underwater because it is just too much work. Here now comes HLG so what is good about HLG and why this can make a real difference here my list:

  1. It is free you don’t need to pay for an upgrade
  2. It is backward compatible with standard dynamic range
  3. Requires a less intensive workflow compared to Vlog
  4. You can produce a decent file recording in camera without external recorders
  5. If you do have an HDR capable external recorder than it shows things are they are and not the washed out version of vlog

This is just my personal list of reasons there may be more.

How to set the Panasonic GH5 to record in HLG and UHD

There are 3 settings that give you the possibility to record HLG HDR compatible files, two are available in MP4 (LPCM) and MOV and one in MP4 (HEVC).

MP4 (LPCM) and MOV

P1040940
400 mbps ALL Intra

P1040941
150 Mbps LongGOP

There are not many cards that can work at 400 mbps and they are expensive. In any case do not assume that 400 mbps ALL-intra is better than longGOP as longGOP is fairly efficient and if you look into the various YouTube videos you will see it is very hard to see any difference unless you do pixel peeping.

MP4 (HEVC)

There is also a convenient low bit rate format available that uses HEVC in camera you can access it selecting MP4 (HEVC) in the REC FORMAT menu

P1040942

You then have this option available

P1040943

Tests show that when done real time HEVC produces files 50% of H.264 so the bitrate makes sense however unless you want to play the files directly on your Tv this is not such a good choice as the files are too hard to edit with any computer as there are no H265 hardware accelerated display widely available.

So the format of choice is as follows:

REC FORMAT: MP4 (LPCM)

REC QUALITY 422/10 bit/LongGOP 150 mbps

Please note the format at 50/60p does not give HLG in camera only the HDMI output is HLG compatible this is because the output is 10 bit as required by HLG. 8 bit colour does NOT qualify for UHD HDR so if you use this format in camera the HLG photo style will be greyed out.

How to convert 150 mbps HLG LongGOP files

At time of writing only programs like VLC play the H264 10 bit files produced by the GH5 and on my computer they play badly. So when you will go and edit those files your NLE program will most likely convert them into a format that is easier to digest and still supports 422 10 bit colour, this format is Apple Prores.

Unfortunately unless you have a paid software the files will only be unreadable if you use DaVinci Resolve or iMovie. However you can use a command line encoder like ffmpeg and convert all those files for free.

The command once you have the executable and you have the files in the right directory is something like this:

ffmpeg -i GH5file.mp4  -c:v prores -c:a copy GH5file.mov

This tells ffmpeg to transcode the video to prores 422 and to just copy the file as is (prores uses linear PCM for audio) here you notice that the source file has mp4 and the destination mov that is the default for prores and the reason to set your GH5 to record mp4 and not mov.

I have developed an automator script that is able to convert all selected files in the memory card and place them in a location of choice on the hard disk or else.

automator

Ffmpeg will convert using prores 422 that in my case bumped the files from 150mps to 474 mbps as prores is an all intra codec this is reasonable and there is no reason to use higher version like 422 HQ starting from a 150 mbps longGOP. Obviously if you use an external recorder feel free to use the higher bitrate available.

How to produce your HDR video clip for free

DaVinci Resolve is able to use your prores files converted from the GH5 and produce HDR compatible files.

You need to go into project settings and select colour management and change your settings as shown here

DaVinciProjectSettings

Colour Space Rec.2020 and Gamma Rec.2100 HLG will produce a file that on a compatible Tv will trigger HDR.

Now the bad news if you don’t have an HDR monitor it is very hard to grade properly on a standard monitor although you can look at luminance curves and chroma curves to see if you have situation of bad exposure or saturation this can be tricky with underwater footage so the trick is to try and get it right in camera.

Of particular interest is the HLG View Assist setting on the GH5: as the screen of the camera is not HDR this should help exposing the scene properly but I have to yet determine what is the setting that I prefer.

Well that is all for now…!