Category Archives: UNDERWATER VIDEO

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

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

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

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

Dpreview has a decent sample gallery.

Official Test Data from Sony

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

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

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

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

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

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

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

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

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

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

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

Practical Home Made Test

I sourced a cushion with a complex embroided decoration.

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

Here are my findings.

Centre Performance

800% center crop Left f/4 Right f/5.6

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

800% center crop Left f/5.6 Right f/8

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

800% center crop Left f/8 Right f/11

Stopping down to f/11 gives a mild deterioration.

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

Edge Performance

Let’s see the situation at the edges.

400% edge crop Left f/4 Right f/5.6

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

400% edge crop Left f/5.6 Right f/8

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

400% edge crop Left 8 Right f/11

At f/11 the edges are ok.

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

Full resolution examples here

28-60mm 28/4
28-60mm 28/5.6
28-60mm 28/8
28-60mm 28/11

Consideration for use underwater

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

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

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

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

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

Additional Information

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

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

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

This is a 200% crop of the edges

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

Few videos from the Red Sea Image Makers Trip

I only did 4 video dives during the trip and one of them was not really good. This is a short video of the other 3 plus the dolphin experience

Valeri did a much better job with his Sony camcorder in Gates housing and produced this outstanding HDR video

I think it was beneficial for him to be on the boat together as I saw his craft getting better and better during the trip.

The inside of the Thistlegorm are one of the highest quality video examples I have ever seen so well done Val!

I have been thinking if I should do this trip again in the future or switch to something different for example macro in the Philippine I am interested in hearing your views!

Environmental Conditions joy and despair of the photographer

A few weeks ago I went diving in Swanage with BSOUP the British Society of Underwater Photographers that I have recently joined.

I was looking forward to some local diving so when I found out that they were organising a trip I managed to get on.

I drove there the night before and I was number two on the pier the next day.

It was a deceiving clear morning with perfect conditions on land.

I had two cameras one in the housing and one for land use so I took a few snaps.

Once parked on the pier I was informed by two friends that dive locally all the time that it was better to wait when the water level was a bit higher.

At that point it did look like a great day however there was a bit of wind.

I had my GH5M2 with the Panasonic 45mm macro that I acquired last year and has become my favourite macro lens.

I jumped in the water one of the first to find out the visibility was well maybe 1 meter? I could not see the LCD screen of the camera due to the suspended particles and had to use the viewfinder

One of the first things I say was this corkwing wrasse with a massive parasite near its eye.

Unfortunately I did not have a snoot or strobes suited for the challenge so I spend the first dive training myself on how to get the least amount of back scatter. Mind you when there are particles you will have backscatter not matter what you do.

Static subjects are ideal for testing so I had a go at some really simple stuff.

And again some anemone the object was to get the cleanest possible shot.

When I was reasonably happy I moved to some more interesting subject I gave up on blennies as I knew everyone would have shot some and besides my strobes were not the best for the situation and I found a cooperating cuttlefish.

I can tell you that to get this clean shot it took me quite a while but on reflection despite being very low I could not even see a hint of the surface so bad the conditions so I decided to get really close.

I wanted to emulate a profile of a person or perhaps an elephant not sure but I took a number of shots waiting for the tentacles to be in the right position and this is my best shot for the day.

I would say it is quite creepy but after all I had something decent and when I presented the shot in the club review at the sailing club it got some good feedback.

Now with that in mind let’s have a look at some shots taken in clearer water this is from Sorrento Peninsula.

Blenny Gold

You can see that clearer water improves contrast and sharpness as you would expect however as the UK shot was very close the gap is not as big.

And this is a shot from last time I was in the red sea

This is super macro so again suspended particles are not as important.

However if we look at a mid-range shot similar to the whole cuttelfish the situation is very different.

Here we are in Italy.

The Look

And finally here in the red sea.

Napo Lips

For as much as we may love our local dive site there is a degree of adaptation but also a restriction on the variety of shots we can take.

When I was working as resident dive instructor I remember the guidelines we were passed one was really funny and said:

“if the visibility is crap you don’t say that to the guests what you say is today we are going to focus on macro” then you make sure you choose a site where there is some.

I am looking forward to my boat in the Red Sea end of July remember if you follow me on instragram there may be some voucher codes to be used for discount.

If like me you have been trying to make the most of your local dive site you deserve to get yourself in clear water where you can actually see further away than your arm. Of course we do have some good days in England sometimes 5 even 8 meters but I tale Egypt and their 25+ meters any day of the week!

A closing thought on conditions and land photography, in fact even if visibility is not an issue most times unless you have fog, overcast days, excessively clear days do not make great land pictures either so we can say we are always on a quest chasing light and conditions.

Panasonic GH5M2 and GH6 HDMI Lag Optimisation

Key Facts

  • The camera live view is one frame behind due to the image processing pipeline, faster refresh rates reduce delays
  • HDMI latency does not depend on cable length
  • Most monitors have low latency
  • HDMI can carry audio and video and those need to be synchronised: if one of them is slower than the other a delay is introduced to match up
  • Resolution plays a role but not as important as others

GH5M2 and GH6 Lag between LCD and HDMI

  • The camera LCD has a resolution of 960×640 pixels and a refresh rate of 60 fps that can be reduced to 30 fps
  • When recording the camera shows the live view on the LCD with a delay of c 1 frame from real life
  • If you go into the menu HDMI Recording Output and set Sound Output  OFF you can see the real lag between the LCD and the HDMI
  • This lag is typically 2 frames from the LCD 
  • As frame  rate drops the lag increases
  • When the Sound is disabled the lag of the GH6 is generally better than the GH5M2
Measurements Results

Video Tutorial with my recommended settings

Items shown in this video

1. Atomos Shinobi: https://amzn.to/35DmFhD

2. Manfrotto 290 Xtra: https://amzn.to/3sSYggF

3. Manfrotto Light video head: https://amzn.to/3vTCHPc

4. Smallrig Monitor Mount: https://amzn.to/367f22z

5. Smallrig HDMI cable: https://amzn.to/3sVwNe9

6. Panasonic GH6: https://amzn.to/3HTUZlv

7. Panasonic 10-25mm 1.7: https://amzn.to/3KtxAcn

8. Atomos Ninja V: https://amzn.to/3MEKia0

HDMI Optimisation Wrap Up

  • Monitoring has acceptable delays from live time 50-150ms
  • Audio recording introduces a delay of 65ms on the GH5M2 and 35mm on the GH6 
  • The GH5M2 lag  of 190ms in 24p is too high and should be reduced to 160ms
  • There is a bug in the 30p mode on the GH6 as the lag is higher than 24p this needs to be corrected

Panasonic GH6 Power Solutions

The GH6 has the same USB power capabilities introduced in the GH5M2.

In this video I show you what I use with my cameras.

Initially with the GH5 I could only use a dummy battery kit and this will continue to work however it may have challenges with mechanical shutter or very high bitrate codecs of the GH6.

Therefore the recommended solution is a PD Power Bank

Pay attention to the checks you need to do as your power bank needs to deliver 9V 3A which usually means at least 45W better 65W

US

1. Dummy battery kit: https://amzn.to/3sFarxp

2. 65W PD Power Bank: https://amzn.to/35Kh6gW

3. Cheap USB Power Bank: https://amzn.to/3IVhM1u

4. USB C Cable: https://amzn.to/3tnsreQ

UK

1. Dummy battery kit: Currently Not Available

2. 65W PD Power Bank: https://amzn.to/3KgGfih

3. Cheap USB Power Bank: https://amzn.to/3HBGDGk

4. USB C Cable: https://amzn.to/3sGBmcj

Panasonic GH6 my preliminary key observations for Underwater use

I was able to have a 1 hour hands on session with Lumix yesterday and try some of the GH6 features.

Key points

  • Beautifully engineered machine
  • 1 stop dynamic range increase appears to be true
  • LCD design with tilt will make easier to see underwater
  • Records ProRes 422 HQ to CFExpress Card
  • Support HDMI 2.1 (playback only)
  • Battery same as the S5 and newer GH5M2
  • Battery consumption 25 to 35% higher in MP4
  • Significant HDMI lag if you use a recorder (1/4 of a second)
  • Will record to USB with a future firmware update
  • Will record prores raw externally with a future firmware update
  • No battery grip

I am going to do a longer write up once I have tested the camera for land wildife use however I have the following concerns

  1. What is the real battery life when you record ProRes to card instead of the low quality MP4, will it last at least one dive?
  2. HDMI lag is horrible just received confirmation that HDMI recording is capped at 4K resolution This proved to be a red herring as the lag is decreased from the GH5 series see here https://interceptor121.com/2022/03/10/panasonic-gh5m2-and-gh6-hdmi-lag-optimisation/
  3. The lag of the HDMI can be reduced if you use only a  monitor with a few tricks and it only needs HDMI 1.4
  4. The USB recording will be powered by the camera and the battery is already small

My recommendations for a professional grade housing would be:

  • Recording to card either 4K@60 or 5.7@30 depending on your use case
  • Optional monitor to run in 1080p to reduce lag HDMI 1.4 is sufficient
  • PD Power bank inside the housing so you are sure you will not run out for an entire day of shooting

For photography a classic housing would work but then who is going to get this just for photos?

Stay tuned for more information. If there is something you want to know about the camera use the comment feature here.

Panasonic GH5M2 and S series Demystifying Movie recording settings 2022 Update

 

In 2018 I wrote the original article as I had acquired the GH5 and I was faced with a ton of non-sense on which format to use when I was shooting video. With the S series software stack Panasonic has made some changes to the options available and I thought it was about time to refresh the original article. As Before I will focus my analysis on 4K video and ignore other formats. This time I will be looking at the NTSC standard of 29.97 and 59.94 frames per second. This is simply because today majority of content produced by Panasonic consumer digital cameras is consumed online and all computer screen work at 60 Hz refresh rate so shooting anything different than 30 or 60 will result in choppy video. This presents some challenges if you are in a PAL zone and are shooting under artificial lights however for the purpose of this article I want to just ignore this issue, obviously you could shoot 24 fps and hope in a 24 – 30 conversion which is scatty of course. For simplicity I will refer to 30 and 60 fps and not exact values.

Today we have 5 settings for UHD 

  1. 200 Mbps 420 10 Bits Long GOP 60 fps
  2. 150 Mbps 420 8 Bits Long GOP 60 fps
  3. 100 Mbps 420 8 Bits Long GOP 30 fps
  4. 150 Mbps 422 10 Bits Long GOP 30 fps
  5. 400 Mbps 422 10 Bits All-Intra 30 fps.

The last option is only available on the GH5 series and on the S1H. The first option is only available on the S series and the GH5M2. 

Long GOP vs All Intra

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.

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/HEVC 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.

So which format should you choose?

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 30 fps this means circa 13.4 Mbits per frame or  1.67 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 but only CAVLC coding is used, this makes the resulting files easier to read and to edit. The idea of All intra is that you don’t require powerful hardware to edit without conversion in an intermediate codec. However based on my experience this is not entirely through and you need a decent GPU to play it back and edit real time without issues.

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.

it would appear that All Intra 400 Mbps would fall short of Apple recommended bit-rate for 422 10 bit colour however practical tests show that AVC All intra at 400 Mbps is perceptually identical to ProRes 422 HQ and uses much less space. We also did some SNR measures time ago with the friend Paal Rasmussen and we did not find significant improvements shooting ProRes 422 HQ vs All-I on card.

Long GOP Codecs

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 GH5M2 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 on the H264 implementation is here: documentation

There is unfortunately no documentation of the HEVC implementation that I have found to date.

200 Mbps 420 10 Bits Long GOP 60 fps Analysis

An analysis with ffprobe shows a GOP structure with N=30 and M=1 where N is the length in frames of the group of pictures and M is the distance between I or P frames.

This codec does not have B frames but only P frames.

Analysing a set of I frames of a fixed subject at 60 fps resulted in a frame size of 1.16MB for the I frames. This value is quite low however we need to understand that HEVC is much more efficient than H264. 

I shot this test video time ago comparing the recording of this codec with a Ninja V in ProRes 422 HQ. As you can see no major differences however I have not pushed the grading in the clip.

The speed ramps in this video use this codec

 

150 Mbps 420 8 Bits Long GOP 60p Analysis

An analysis with ffprobe shows a GOP structure with N=30 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

IBBPBBPBBPBBPBBPBBPBBPBBPBBPBB before it repeats again.

Analysing a set of I frames of a fixed subject at 30 fps resulted in a frame size of 1.26MB for the I frames.

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 however the additional frames result in better slow motion performance than what is done in software in majority of cases.

100 Mbps 420 8 Bits Long Gop 30 fps Analysis

An analysis with ffprobe shows a GOP structure with N=15 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

IBBPBBPBBPBBPBBP before it repeats again.

Analysing a set of I frames of a fixed subject at 30 fps resulted in a frame size of 1.49MB for the I frames which is the highest if we exclude All I.

150Mbps 422 10 Bits Long Gop 30 fps

An analysis with ffprobe shows a GOP structure with N=15 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:

IPPPPPPPPPPPPPP before it repeats again.

Analysing a set of I frames of a fixed subject at 30 fps resulted in a frame size of 1.25MB for the I frames.

H264 Codec Ranking for Static Image Quality UHD

So in terms of absolute image quality and not taking into account other factors the Panasonic GH5M2 and S series Movie recording settings ranked by codec quality are as follows:

  1. 400 Mbps 422 10 Bit All intra 30 fps (1.67 MB per frame)
  2. 100 Mbps 420 8 Bit Long Gop 30 fps (1.49 MB per frame)
  3. 150 Mbps 420 8 Bit Long Gop 60 fps (1.26 MB per frame)
  4. 150 Mbps 422 10 Bit Long Gop 30 fps (1.25 MB per frame)

The 100 Mbps  and 400 Mbps codec are marginally different with the 150 Mbps long GOP really far away.

Note that as the technology is different I cannot directly compare the new 200 Mbps codec however based on visual impression and ability to grade I would recommend this over the 150 Mbps 420 8 bits

Conclusion

If you have a camera that has the 400 Mbps All Intra this remains the best format  to use. V90 cards have dropped in price and are now available up to 256 GB. Unfortunately this option is only available on the GH5 series and on the S1H.

If you have a camera that does not have the All-I you can of course purchase an external recorder that in some cases will allow you to shoot RAW however this is not necessarily going to give better image quality and will definitely extend your processing time.

My revised advice, if your camera does not have the ALL I and you don’t have an external recorded, is as follows:

  1. Use the 100 Mbps Long Gop codec it is very efficient in the compression and the perceived quality is very good. 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 but this based on experience is not very high. 
  2. Use the new 200 Mbps HEVC for double frame rate it is not hard to process as HEVC 10 bits has hardware acceleration on all platforms.

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, in addition the lack of hardware acceleration for H264 10 bits means you will need to convert the files for editing and they do not open with standard programs or load on phones or tablets. The same is true for All Intra but at least you can edit it ok.

To conclude this is a summary table with all key information

Screenshot 2022-01-24 at 18.01.50

Additional Considerations

A certain number of GH5 users have upgraded to the S5, I was one of them until I sold the camera after 1 month of using and after buying a Ninja V. If you are a Panasonic S1/S5 user you need not only to contend with recording time limits but also with lack of codecs on the camera to fully use the potential that it has. You need to add an external recorder to really see the benefits because in real life situations you are not shooting a step chart so the dynamic range is destroyed by compression quality and errors and SNR drops. It would be interesting to test how does the GH5M2 400 Mbps compare with one of the S cameras using the 150 Mbps 10 bit codec but this is not something I did. I would only warn everyone going down that path that you may get less than what you think and you may require additional hardware to get there. Take also into account that S series only shoot 50/60 fps in APSC/Super35 mode and that in full frame mode there is a substantial amount of rolling shutter that makes pans and tilt practically not possible.

Back in the water Sorrento Peninsula 2021

Although COVID-19 vaccinations are starting to make a difference and travel is resuming is fair to say that we are still far from where we were in 2019 and it may take some time to get back there.

This means our diving travel destinations have been changing and there is much more local diving than before. Big countries like the US have a lot of diving and Caribbean destination on their doorstep those travellers have still quite a lot to choose in comparison to others.

For Europeans, in the geographical sense, there are options for short haul travel. Those do not compare to your macro trip to South East Asia or pelagic trips to South America or Maldives or similar, however you can get some pretty good shots.

In 2020 I had my first experience in Massa Lubrense and this year I was back there.

I wrote about it last year if you are looking for more details on the logistics so in this post I will focus on photography.

Getting back into RIB diving

After 1 year of forced stop from boat diving getting back into a RIB diving with 15 liters steel tanks was a bit of a shock, certainly better than shore diving but yet not exactly streamlines especially as I decided to get a semi-dry suit. Due to stock shortages in UK I was only able to fit into a Scubapro Nova Scotia 7.5mm that has a lot of buoyancy. The suit was definitely toasty but required a lot of weight to go down as it was brand new. Temperatures range from 26 degrees at the surface to 17 at depth in certain sites so after a chilling experience last year this time I was definitely ok.

I did 2 sets of 3 days diving clocking a total of 16 dives. The dives were all close to 60 minutes (time to get back on the RIB by procedure) and depth of 33 meters. I have to say I avoid decompression dives but really this destination does require you to dive deeper than what you expect in tropical destinations.

Camera Equipment

I had the new Panasonic GH5 Mark II that fits in the housing of the Mark I and two Sea and Sea YS-D2 strobes. I took only two lenses the Canon 8-15mm fisheye with metabones smart adapter and the new (for me) Panasonic 45mm 2.8 macro.

The zoom fisheye rig looked exactly like the one in the site menu.

Wide Angle

The visibility can be an issue on the Italian coast however you can mitigate the issue with good technique and photoshop. Interestingly water is always clearer at depth where of course you lack light so strobe power is important to get a good shot.

Banco di Santa Croce is the best spot to meet large grouper and has many sea fans and also macro life, eagle rays and other things to be found.

Grouper resting between red gorgonians
Two groupers chasing

I find also very interesting the schooling fish even if this is usually not well behaved Barracuda who never spin around or a variety of sea bream

Barracudas at Scoglio Penna
Saraghi (breams) at Scoglio Penna

For me the most interesting wide angle though are the cave shots at Scoglio dell’Isca and Punta Campanella

Halloween: multiple entrances to the Isca
Zoom on the lower entrances
Schooling cardinal fish at Punta Campanella

Sunburst opportunities are abundant and due to the depth relatively easy scorpionfish or small sea fans are ideal.

Sunseeker

The performance of the Canon 8-15mm on micro four thirds is just legendary!

Close Up and Macro

Afternoon dives at Puolo but also dives in Santa Croce or Mitigliano offer lots of close up opportunities.

It was the time of testing the Panasonic 45mm 2.8 on land I had the impression it gave better rendering of the Olympus 60mm and I definitely prefer it underwater.

Male Anthias in breeding coloration
Blenny with shrimp on his head standing on a cuttlefish!
Golden Blenny
Mating nudibranches

It is not just macro a long lens gets interesting closeup of large groupers

Tompot Blenny Head On

Wrap Up

Diving in Italy delivered again. I am seriously thinking a group trip would be worth it next year based on the itinerary I sketched last year.

Dates for 2022 would be 4-11 September outside of school holidays the diving is really calm as most Italian divers are back to work and the conditions are usually superb. If you are interested leave a comment and I will come back to you with costs and planned itinerary.

Travelling light – Part II on the field

Disclaimer: there are many USB power banks on sale however most of them do not declare the maximum output current and therefore you cannot be sure that it will work in all situations I describe. The equipment I use does work and is proven by my daily experience, the suggestions are not prescriptive but if you choose your own parts you do do at your own risk

It has been some time since my post on chargers and recharge facilities. During the pandemic I have done a considerable amount of land based photography including wildlife, landscape and astrophotography so I have had the opportunity to develop the concept of portability further on the field. So I wanted to share my experience with you all as some of the findings are beneficial in every day situation.

Charging your camera battery

Today some cameras can charge the battery in camera using USB. In almost all cases the camera needs to be turned off to allow charging, as a complete recharge of your battery can take a few hours I never use this method. I always rely on spare batteries typically 3 and a dual battery charger that can be powered using USB. I use Newmova they are cheap and cheerful for both my Panasonic and Olympus cameras.

Newmowa Dual USB Charger for Olympus BLH-1 and OM-D EM1 Mark II, OM-D E-M1X Camera £9.99

Newmowa Dual USB Charger for Panasonic DMW-BLF19 and Panasonic DMC-GH3,DMC-GH4 DMC-GH5, DC-GH5S(DMW-BLF19 Dual USB Charger) £9.99

With 3 batteries you can have two in the charger if needed and one in the camera which means uninterrupted shooting for a long period of time depending on your use.

Battery Grips

I also use battery grips in particular for my Olympus camera. Battery grip provide the most benefit when you are not wanting to interrupt shooting while swapping batteries. I usually set the camera to use the grip battery first and the camera as back up which means you can then insert another battery in the grip and keep shooting. I do not recommend using a battery grip as a sole source of power as at the end you can can go through 2 batteries relatively fast if you use quick burst shooting. The other dis-benefit of the grip is the one battery is always locked inside the camera so you need to increase your total battery stock to 4 if you use a dual charger. The grip is very useful to shoot verticals and provide weather sealing but overall is not my favourite option and I only use it for specific session on my Olympus camera because I only have 2 batteries.

There are some working 3rd party battery grip like this one that function AS LONG AS YOU USE ORIGINAL OEM BATTERIES.

Neewer Battery Grip Compatible with Panasonic Lumix G9 Camera Replacement for DMW-BGG9 with Shutter Release Focus Point Control Joystick £59.99

I have not seen versions for Olympus camera and the original battery grip is expensive. I got mine second hand for a good price.

Again if you only have two batteries or you want to rotate 4 batteries a battery grip is a good option if you don’t mind the extra weight.

Power Banks

I use a relatively simple USB power bank as I do not have PD capable cameras. This power bank has a decent capacity but more importantly it can output 4.5A using two outlets.

RAVPower Portable Chargers 16750 16750mAh External Battery Pack 4.5A Dual USB Output £24.99 

This power bank has also a light included very useful for your night photography. You can also use it to charge your phone but with two outlets means you can power two dual USB chargers and effectively charge 4 batteries twice until it runs out (typical battery less than 2000 mAh).

This power bank can also be used as constant power supply for cameras that take a dummy battery and do not support powering through USB.

DMW-DCC12 USB Power Cable kit DMW-DCC12 DC Coupler Dmw-Blf19 Dummy Battery (BLF-19 Battery Replacement) Compatible with PANASONIC DMC-GH3 DMC-GH4 DMC-GH3K DMC-GH4K DC-GH5 GH9 and more Digital Cameras £22.99

Using the power bank with this fake battery kit means I can run my GH5 in video for days (8.72x batteries equivalent charge).

IT IS VERY IMPORTANT THAT YOUR POWER BANK OUTPUTS MORE THAN 3A OTHERWISE IF YOU USE MECHANICAL SHUTTER THE CAMERA MAY GO IN SHUTTER VIBRATION AND SUFFER PERMANENT DAMAGE

Some well know power bank from respectable brands like anker and even rawpower themselves only outputs 3A current total so when the mechanical shutter is used and the camera draws more current you run into issue. This also happens when you set a custom white balance and the camera triggers the mechanical shutter. So if you have such power bank you are limited and hence I do not recommend them.

If you also use flash you can use the same chargers I already linked in the previous article

Prices have dropped to £7.99 for the micro USB and £9.99 for the dual USB C and micro USB input. Note that despite the misleading description the two chargers are identical except one has micro USB and the other also USB-C. The USB-C version is slightly bigger (70x90x23 mm USB version vs 97x114x34mm USB C). The USB C version has a stronger output for AAA batteries that I do not use and it does not charge faster standard AA so don’t be mislead.

EBL 40Min Smart Fast USB Battery Charger for AA AAA Ni-MH Rechargeable Batteries
EBL 2-hour Super fast AA AAA Rechargeable Battery Charger with Battery Intelligent Auto-detection Tech for 1-4 NiMH Rechargeable Batteries

Dew Heaters

Another useful accessory if you do astrophotography in humid or cold environment is a lens warmer. There are two versions I recommend the one with the temperature regulator as the strip gets to 50 C and this can increase dark current noise in your shots.

COOWOO Lens Heater Warmer Dew Heater with Temperature Regulator Strip for Ice Fog Universal Camera Telescopic Bottle Heating (Black)

Amazon.com links for my American followers

EBL 40Min Smart Fast USB Battery Charger for AA AAA Ni-MH Rechargeable Batteries

DMW-DCC12 USB Power Cable kit DMW-DCC12 DC Coupler Dmw-Blf19 Dummy Battery (BLF-19 Battery Replacement) Compatible with PANASONIC DMC-GH3 DMC-GH4 DMC-GH3K DMC-GH4K DC-GH5 GH9 and more Digital Cameras

Neewer Battery Grip for Panasonic G9

RavPower 16750 mAh 4.5A dual USB power bank

NewMowa Olympus dual charger

NewMowa Panasonic dual USB charger

COOWOO Lens Heater Warmer Dew Heater with Temperature Regulator Strip for Ice Fog Universal Camera Telescopic Bottle Heating (Black)

Choosing the appropriate gamma for your video project

The previous post on the technical nature of V-LOG has stirred up quite a bit of unset among those people that advocate the use of it as a preferred gamma for video capture. In this post I will show some data point to help you make an informed decision based on what you are planning to shoot in your video project.

Basics of Display Gamma and Dynamic Range

First of all a bit of background on gamma curves. The standard video gamma is based on a correction factor of 0.45 as screen decode it with the reciprocal value 2.22.

Cinema gamma is historically based on a value of 1/2.6 as projectors decode with a gamma of 2.6.

Today most of our content is consumed on phones, monitors or Tv screens as well as of course cinemas but for the purpose of this post I will assume we do not have a real ambition to project in cinemas.

To give some ideas of the dynamic range of the display consider those values

Phone (HDR)9+
Computer Monitor10
Tv (1886 HDTV)11
HDR Tv13+
Projector16+
Typical Display Dynamic Range

It is important to understand how the content we produce will be consumed when we capture our source material as otherwise our video pipeline may be suboptimal.

Mobile phones and tablets are now the predominant platform to consume content and looking at the table above this means that in terms of dynamic range there is not a high requirement. In addition phones and computer monitors may also not be particularly accurate in terms of colour rendition.

HDR content, due to lack of widespread compatibility, is growing on mobile phones but remains a product for high end platforms such as HDR TVs and Projectors.

It follows that content that will be displayed at the best quality on the most common platforms has pretty limited requirements in terms of dynamic range and other qualities are perhaps more important such as sharpness, low amount of noise, colour rendition and delivery of what looks high contrast on a limited contrast medium.

A further obvious consideration is that standard rec709/sRGB video is limited to 10 stops of dynamic range in the display (contrast ratio 1000:1) while new TV sets aligned to BT.1886 can display 11 stops )(Contrast ratio 2000:1). So no matter how you acquire if you end up in rec709 the dynamic range is limited and it becomes more important to accurately capture tones and colors.

Gamma Curves for Capture

As explained capture gamma is the reciprocal of display gamma and therefore majority of cameras capture a standard video gamma (0.45) or in some cases an HDR gamma (logarithmic). I do not want this post to become a deep dive on HDR video of which I have written enough however to stay on course I want to compare traditional gamma (non linear) and log gamma.

In the following graph you see the bit codes output vs input of a standard video gamma (1/2.2) a cine gamma (1/2.6) and a log gamma (v-log).

Bit code mapping for 14 bits linear sensor data

In broad terms you can see that a video gamma produces an output of 3865 vs 16383 bits, a cinema gamma sets at 3166, while a Log gamma can take all 14 bits of data and still be within bit value 960.

It follows that to store the whole set of values read at 14 bits into a 10 bits container a standard gamma needs to do some scaling while a log gamma does not need scaling to fit into a 10 bits container. This also explains why exposure values in log are 2 stops higher than standard video for a 14 bit range, while for a 12 bit range the offset is one stop. As the meter is using a standard RGB gamma all values are rescaled back.

You notice that at no point here I have made references to dynamic range. The camera dynamic range is solely related to the maximum well capacity vs the read noise and it does not relate to the gamma curve being used, however the different compression of the gamma curve have an effect on how tones are mapped and on the perceived dynamic range.

Camera Dynamic Range vs Display Dynamic Range

The overall camera dynamic range influences what you can do with your content and if it is worthwhile to produce an HDR version or not.

If we compare the previous table of display dynamic range vs camera dynamic range and we focus on nominal values (SNR=1) and photographic (SNR=20) we can see what device we need for our purpose.

Camera TypeDRPDR (SNR=20)
Compact 12.99.8
MFT12.310.3
APSC1411.1
Full Frame1412.2
Dynamic Range by Sensor Type

We can see that if all we need to do is to output on a mobile device or a computer monitor smaller sensor are adequate, however for HDR production larger format are preferred. Obviously we can stretch SNR to lower values and this will upgrade the above table of 1 stops or so but not change our reasoning substantially.

Gamma curves vs Bit codes mapping

The various gamma curves have a different distribution of tones (bit values), in this table I compare a video gamma vs cinema a reduced 12 stops log and a full Vlog for a full frame sensor camera.

For the purpose of this comparison blacks are bit codes in the lowest 10%, Shadows are up to 18%, midtones up to 75%, highlights up to 90% and whites above. Blacks and whites do not have color information but just brightness while shadows, midtones and highlights contain respectively dark, medium and light hues.

Distribution of tones vs Gamma

A standard video gamma has over 45% of midtones, those are the colors and tones with intermediate values so produce softer tones. Shadows are just above 35% with highlights under 10% and blacks and whites around 5%.

If we look at a cinema gamma we can see that shadows are now predominant and very close to the midtones, highlights, whites and blacks are compressed.

V-LogL (12 stops DR 12 bit implementation) has the largest range in shadows, midtones are compressed around 50% compared to a video gamma, blacks are subtantially more than a video gamma, and while highlights are compressed, whites are super whites are greatly expanded.

Full VLog is dominated by whites that make 38% of the bit values, Shadows are at 32% with midtones now under 20% and highlights compressed. Blacks remain expanded.

Choosing a Gamma Curve for your Video Project

Our decision tree starts from the content which determines the device we need. Once we have a device capable of a given dynamic range we can make appropriate choices in terms of gamma curve.

Broadly speaking compact cameras and micro four thirds do not have enough device dynamic range at sufficient level of SNR to justify a high dynamic range gamma. There are some very specific exception where this may be worth it (Panasonic GH5s) but in general terms a standard MFT camera for photography should be limited to video or cinema gamma for optimal results as the dynamic range is limited and compression is not required.

If you own an MFT camera your choice is between a video gamma and a cinema gamma. Depending on the look you want to achieve you may choose one or the other. Video gamma has generally more contrast (more blacks and highlights and whites) while Cine gamma has a balance between midtones and shadows but not strong blacks and whites giving overall a softer look.

If you own a full frame or apsc camera you have more options which means you need to think more about the gamma curve to be used. HDR content requires a log curve you can then decide to use a cinema or video gamma if you do not want to output HDR or want to achieve a different look. It is important to note that log gamma have lots of bit values in whites and super whites and those do not exist in many typical scenes.

Scene vs Dynamic Range

While the current effort of camera manufacturers is to promote high dynamic range the reality is that in most cinematography situation you use devices that reduce contrast and therefore dynamic range (think about pro mist filters).

The DR of a scene can be evaluated looking at the histogram. This is of course influenced by the gamma curve so it is important to do this evaluation taking a photograph not video.

The following are example of scenes with the underlying histogram.

High Dynamic Range scene note the shape of the histogram with peaks on darks and lights
indoor scene with mostly midtones
Low contrast portrait despite the light background
Underwater landscape that does not have as much DR as you would think
Moth image predominant in midtones
Outdoor image with low dynamic range
Typical indoor party scene with flash does not have significant dynamic range
The same portrait with a cine gamma sees enhanced shadows and lighter overall image but with bright tones subdued

It may be useful to see the effect of LOG using the LUTs in photoshop on the raw data

Original image
Vlog image
Vlog + LUT back to Rec709

The example above shows that a significant number of midtones have been lost in the conversion with no DR benefit as the scene essentially lacked it.

Conclusion

For underwater video purposes as the water reduces contrast and smooths highlights I would not recommend shooting log or HDR with the exception of very specific scenarios. Likewise if I am shooting a v(ideo)log or an interview there is no requirement for extra dynamic range and log compression is not required.

Outdoor scenes especially in bright conditions, snow, are appropriate for HDR and should be shot with a log format assuming of course the luminance of the scene is not being reduced with ND filters or similar.

Events like weddings can have challenging conditions with a mix of low contrast indoor and bright outdoors with the bride typically dressed in white so in effect those can be very demanding on the equipment but you need to bear in mind that if your delivery format is just HD video the benefit of log gamma are greatly reduced and extensive work may be required to bring colours back in check, always account for the limitations of your equipment as well.