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Offline Last Active Dec 04 2016 11:44 PM

#379269 Sony a7s II underwater use -- All parameters

Posted by dreifish on 01 December 2016 - 02:18 AM

Hmm.. what? Nothing school-bus sized? Boring! :D

#379025 Underwater Colour Correction With The Sony AX100

Posted by dreifish on 23 November 2016 - 12:12 AM

If no one has, I have an RX100 mk1 that I can have a try on. Water here is just green rather than blue.


I'd be interested to hear also: how does the AX100 compare with the RX100 MK4 or (soon MK5) underwater?

It seems to be a clear win for UW video to buy the RX100 MK4/5 given same sensor, codec, bitrates etc. - camcorder ergonomics go out the window anyhow with UW housing.


The ergonomics of the Gates AX100 are going to be head-and-shoulders above a still housing for the RX100 line when filming video. Things like a flip-in-flip-out red filter, adjustable boyancy/trim characteristics and a 12x lens/Gates GP34A wet lens combo that lets you shoot everything from 100 degree wide angle to near macro without any lens swaps may seem like small differences, but they make a big difference if you're primarily a video shooter.

#379022 Sony a7s II underwater use -- All parameters

Posted by dreifish on 22 November 2016 - 05:06 PM


Thanks very much Andrei.  These are very helpful, for next time.  I was shooting at f8, and sometimes at f11.  I pretty much agree with everything you say here.  I am sure I can get better results and I wish I had used the zebras.  You suggested that last time and I did not implement it.


And I agree about not shooting into the sun.  Sometimes, however, the subject presents itself and if you want to film it, you just have to film it where you see it.  Here, I was not able to set up ideal conditions, but was pretty much scuba diving and looking after my girlfriend -- considering myself a documentarian while filming everything I could that looked photogenic.  I was eager to record things, in part to document the coral and fish species, and I am going back and attempting to identify as many of them that I can, so that I can become more knowledgeable about the ecology in the area.


Much room to improve.  Only wish I had more time to dive!


I was having a lot of trouble getting close enough to fish to get good portraits, with this wide angle set up.  Any suggestions on that?  I wonder what things would look like with just my 28mm on.  


In any event, the next challenge is setting up a new dive trip to try to continue to improve.  This last trip was expensive!  Am still looking at Indonesia.  We loved it.  


For anyone reading this, any suggestions?






Depends how small of a fish you're talking about, but I find the 16-35F4 lens to be very versatile on the A7RII because you can film in either full frame or APS-C mode. Turn on APS-C mode, and you suddenly have a 24-50mm lens on. At the 50mm lens, it should be quite adequate for portraits of medium fish. For things that are smaller/more shy, you can use the 90mm macro (inside the same dome as the 16-35 or in its own macro port).


The 28mm by itself isn't a particularly versatile lens. The 16-35 does everything it can do and more.


It's going to be tough to find any place where the reefs are as vibrant as in Raja Ampat. Perhaps try Komodo between April-November. The reefs aren't quite Raja Ampat level and the biomass of fish is lower, but it's as good as it gets in Indonesia outside Raja Ampat. 

#378993 Sony a7s II underwater use -- All parameters

Posted by dreifish on 21 November 2016 - 05:41 PM

Ok guys.  I just posted the first little film from my Raja trip.  All this footage was shot at the same dive site -- the "Magic Mountain" that Ammar and I visited.  I was following the advice of several people on this topic.  I shot this exclusively with UAWB, and video lights when I could.


I started off using manual exposure control, and could get great results, but I was constantly having to adjust exposure.  When you are an ambient light photographer "running and gunning" on a dive like this, it really helps to use auto exposure, as every time you change the view, the exposure can change.  For example, capturing a scene shot into the light, or with the sun in the frame like many of these shots, is quite different from what you might do if you merely turned around and shot the other way.  Thus, I got passable results using auto ISO underexposed .7 stops, usually. 


This was shot with the a7s II.  I think the low light capability of the camera really makes it helpful in shooting ambient light.  Next, the waters varied from murky, to a little less murky, and were never anywhere as clear as either Grand Cayman, or Cozumel.  (This is one reason why there are 100 times more fish).  I think it also very much helped the white balance issues, which pop up when the water is too blue and clear.  Thus, AUWB works better in murky water, when you use video lights in particular. 


Nice footage and interesting observations, George. I'm not sure I agree that the low light capability of the camera is all that useful for underwater filming because the situation you're often dealing with with ambient light shots is too much light, not too little. I can't think of a situation where I've had to use an ISO higher than 1600 underwater, and, for all practical terms, I never go above ISO 800. 


I agree that fixed aperture, fixed shutter speed auto ISO gives the best flexibility for "run and gun" work with the least need to adapt to changing lighting conditions. But sometimes locking the ISO as well can have some advantages, as I'll discuss below.


As others have commented, some of your footage is over exposed, even at -0.7 ev. But if I'm correct about the cause, I don't think the solution is to go to -1.0EV. Rather, you need to be aware of your shooting conditions and start to get a feel for the ambient light. What do I mean by this?


First, a number of the shots are into the sun. When shooting ambient light video, it's usually best practice to try to keep the sun behind you to reduce the dynamic range of the scene, reduce lens flaring effects, and get the best mid-tone contrast. This is true even when shooting with lights, because video lights aren't as powerful as strobes, so they can't light the foreground properly if you're underexposing to keep the sun from clipping half of your scene.  Keeping the sun behind you can be tricky with a really wide lens, but start to develop the habit of looking around for where the sun is and anticipating the action so you can position yourself in the best place to film it while keeping the sun behind your shoulder. In the long run, this will help you get much more vibrant footage.


Second, what aperture setting were you using? One of the dangers of going with auto ISO is that you lose awareness of what ISO the camera is actually using. So, for example, if you're shooting in very shallow water in bright conditions, the camera will be using its lowest ISO (ISO 100). It will do so whether you have your EV set at 0, -0.7, -1, or -2 for that matter, because it can't go any lower. And the results will always be overexposed because your combination of shutter speed and aperture are simply letting too much light in. I've noticed this is a common problem in shallow water during mid-day dives if shooting at 1/50 or 1/60 with the aperture at F8 or sometimes even at F11. This is why I keep the zebras (100+IRE) on to stay vigilant for overexposure. So remember, when shooting in the shallows, check to see what kind of aperture and shutter speed combination you need to get proper exposure at ISO 100 rather then just relying entirely on auto-ISO to do the trick. Odds are you might have to bump your aperture up to F16 and/or even double your shutter speed to 1/100 or 1/120 to limit the ambient light. This is not optimal as it may soften your image a bit because of diffraction (narrower apertures) or create less inter-frame blurring than would be ideal (higher shutter speed), but, in practice, I haven't noticed perceptible degradation in quality in the resulting video. If it's really a concern for you, use a 2-stop neutral density filter or orange/magneta filter which will also block 1-2 stops of incoming light and allow you to keep the aperture at F11 and shutter speed at 1/50 or 1/60.


It's interesting to hear that you think the murkier Indonesian waters are helping with the white balance problems of the Sony cameras. I need to get myself in the water somewhere with 50+ meters of visibility to see if that kind of blue water breaks the white balancing algorithms :)

#378961 Sony a7s II underwater use -- All parameters

Posted by dreifish on 21 November 2016 - 01:46 AM

Hehe, looks nice. What monitor is that?

#378775 Sony a7s II underwater use -- All parameters

Posted by dreifish on 14 November 2016 - 10:48 PM

I would like to download this test and study it with the vectorscope. At this depth I will go with lights no doubt.
I like the 9900K, but I would touch de BIAS somthing like A5 M4 or A6 M5...
Will try next week at red sea Magic filter is AWB ans UAWB mode to see....


Hmm.. you might want to be careful with pushing the bias towards magenta to that extent to counteract the cooler ambient light, especially when shooting with video lights. It may result in the illuminated subjects being a bit too purple. For example, at 3:24 in your Similans film, the fan coral and the water color strike me as a bit too purple (though it's subtle). It does render the sand and rocky reef a nice color, though.


Unfortunately, the A7RII (and other Sony cameras) do seem to have a tendency to push towards green a bit too much, especially in UAWB mode. The white balance bias is one method to try to correct that. I wonder though if we couldn't achieve a better result by shooting in a custom picture profile (could be based on Gamma ITU709  & Color Mode ITU709) with a negative Color Depth for green/yellow or by changing the Color Phase. So many things to experiment with -- this would obviously best be tested using an waterproof color chart. 

#378770 Sony a7s II underwater use -- All parameters

Posted by dreifish on 14 November 2016 - 09:39 PM

Here is the A7R II different WB modes test video at 20m depth, ambient light.


<iframe width="640" height="390" src="https://youtu.be/--4pRdwSNYQ"frameborder="0" allowfullscreen></iframe>




Not sure how to embed a YouTube video :)


I think it's fair to say none of the white balance settings you tested do much to restore the warmer colors (including Underwater Auto White Balance) in the foreground subject (though it's a bit hard to tell -- ideally need to test with something in the foreground that's red/yellow under torches). This accords to my own testing. I'm not really surprised -- Sony's white balance system caps out at 9900k, and to execute an accurate white balance (e.i. to make a white/grey object record equal levels across the red, green and blue channels) you'd need something closer to 20000-50k at that depth, plus a strong magneta push.


If you have lights and the ambient light isn't too powerful, the best approach obviously is to just set the white balance to something that gives you nice blues in the water column (4300k-4800kl usually works quite well) and use the lights to illuminate the foreground once you're below 10 meters. You can use some warming gels on your lights if the light they produce is significantly cooler than 5000k. 


But if you need to work with ambient light for some reason, the obvious solution is to add a orange/magneta filter to the lens to supplement the camera's custom white balance abilities. It's more inconvenient because you have to commit to using it for the whole dive. The results may also not be to everyone's taste. Here's some screen grabs from test footage shot at 15m and 18m with an orange magic filter, both with UAWB and with a custom white balance done off my palm:




Unfortunately, I don't have any footage shot at the same locations without the magic filter to compare, but you can look at the test footage Ammar shared from 20m to see how much of a difference the orange filter makes.


Note that the SLOG2 images are actually graded (just to boost the contrast so they don't look quite as flat).


I think it's interesting to note that the UAWB algorithm does not really push the reds as much as a CWB does. This has the advantage of preserving a nice blue water column, but the foreground reef and sand isn't quite as vibrant and remains a bit too greenish for my taste. On the other hand, with the custom white balance, I feel like the reds are pushed to the point where it's unnatural, and the water column becomes muddy, with a hint of magenta.


I can't say I really like either result.

#378724 Keldan 8x - flux or CRI?

Posted by dreifish on 12 November 2016 - 11:17 PM

I think part of the answer will turn on what sort of camera you'll be filming with.


Inside a cave, you have no ambient light to outcompete, so the strength of your lights is less crucial if you have a camera that can film clean video in low light (e.g. ISO 3200, 6400 or even 12800 if filming with something like the Sony A7S/A7SII). This is great, because it means you can run your lights at lower power and still get nice footage. For reef shots, a camera with high sensitivity won't help much because it'll be equally sensitive to the ambient light, and what you want to do is have your torches brighter than the ambient light in order to bring back the full spectrum of colors. So, for reef scenes, the more powerful your lights, the better. 


Also keep in mind the inverse square law of illumination -- light intensity decreases proportionately with the square of the distance from the light source. What this means, in practice, is that no light will strongly illuminate objects very far away. Importantly, it also means that varying the distance to the object you're trying to illuminate will be more effective than increasing the power of the light source. 12k lumens may be 50% brighter than 8k lumens, but in terms of reach, you're only increasing the light's reach by around 22%. (In other words, the 12k lumen light will produce the same illumination at 1.22m away as the 8k light would produce at 1m away). I don't don't dive in caves, so I can't really opine about how much of a difference the stronger light would make from experience, but, based on the above, I would say there's diminishing returns to increasing light intensity if your goal is to illuminate more of the cave. 


Regarding 82CRI vs 96CRI -- I haven't seen any specific tests done underwater. I've used some 70CRI lights in the past and use 90CRI lights currently. My impression is that the higher CRI lights tend to produce richer shades of red and yellow. Is it a major difference? I doubt someone could look at footage blindly and tell you if it was filmed with 82CRI lights or 96CRI lights, because there's so many other variables confounding the final result (strength of the lights relative to the strength of the ambient light, etc)  Now, if you were comparing them side by side, you'd probably see a difference. Maybe. But even then you'd be confounding it because one light is stronger.


Once you add cyan filters, CRI goes out the window since by definition the cyan filters are stripping out the reds and the yellows. With cyan filters, neither light is going to have a particularly good CRI. 


If you're still confused, to what I did -- get the Gates GT14 lights. 90CRI and 14000 lumens -- best of both worlds :)

#378676 Sony a7s II underwater use -- All parameters

Posted by dreifish on 11 November 2016 - 03:10 AM

That FLW filter seems like a rather unusual choice for color correction, TaxiDiver. Have you tried it out?  I'm quite curious about the results. What are you using it to achieve underwater? 


Regarding custom white balance, to the best of my knowledge, it's a bit of a pain on the A7 series -- you have to be in one of the picture modes (manual, aperture priority, shutter priority) to be able to set it. It's can't be set directly in the movie mode. You can change back to movie mode afterwards and the white balance will be retained, but it makes the procedure quite lengthy.  Or you could film in the picture mode, but then you don't have the 16:9 crop until you start filming. 


Moreover, just like with the UAWB mode, custom white balance will require a red/magneta filter below 10 meters. The camera's internal white balance range maxes out at 10000 calvins, which isn't sufficient at depth. So you need to filter out some of the blues/greens with a red magenta filter first to allow the camera to produce a more accurate white balance at depth. From my (admittedly limited) experimentation with custom white balance and filters on the A7RII, two issues bother me:

  • custom white balance tends to push too red, even when white balancing off my palm or a brown coral. This produces rather muddy, purpleish blue water column
  • below 5 meters (10 if the visibility is excellent) it invariably creates a pretty flat, low contrast, low saturation image which I find aesthetically unappealing even if it may be technically correct

I've acquired two new red filters (one auto-magic, on ur/pro) which I hope to experiment with more in a couple of weeks when I get back into the water. I've also gotten some blue gels to use on my lights so that I can hopefully film with the filter + light combination at depth. We'll see how the results turn out.

#378602 Sony a7s II underwater use -- All parameters

Posted by dreifish on 09 November 2016 - 01:52 AM


 Thanks buddy. Totally agree, light is terrible to my taste also, and this is after correcting it in Adobe Premiere. First days, I dove 30 to 20m, totally dark and dead. Nothing but rocks. This is why I started to dive and shoot close to surface. Plus poor light condition, visibility was terrible also. Well, now I learnt from the locals that February is the best time for visibility in Raja Ampat.


Raja Ampat visibility can really vary, unfortunately (or fortunately, as it's mainly due to heavy plankton concentrations that bring in bigger schools of fish). It was mostly 5-10m and green when I went in November last year and in February this year as well. Go figure. Sure makes filming pleasing wide angle footage pretty much impossible though.


Anyway, for the shallow shoots, the ambient light and visibility seem just fine to me, but the colors are.. a bit muted, and the footage is often a bit overexposed. Where you using underwater auto white balance mode, or just the regular auto white balance? And what f-stop where you shooting at? I find that in the 0-10 meter range with good visibility, if you're at 1/50 and iso 100, you need to push your f-top to at least F11, maybe ever F16 or you will overexpose because there's just so much light. Watching the histogram and having zebras at 100+ to help you spot over exposure is a good practice. 


It looks like you tried to use lights in a lot of the shallow shots also, but, because the ambient light was still quite strong, their effect isn't so obvious. When you're shooting with strong ambient light, your video lights tend to be outshone by the ambient light and don't really bring back much reds/yellows. Best conditions for video lights are deep (30m+) or dark (overcast, early morning, late in the day) when the sunlight that penetrates isn't so strong. Or night, of course :) Conversely, for shallow shots with strong ambient light, you can just go with the underwater auto white balance mode (keeping the sun behind you if possible) and get pretty good results without the video lights. 

#378368 Sony and its frequent camera releases: is it positive or negative?

Posted by dreifish on 01 November 2016 - 07:27 PM

It's all about the output, right? It's not like your old camera suddenly becomes any less capable once a replacement model comes out. So long as your work wouldn't benefit from the new features, why upgrade? And if your work would benefit from the new capabilities, then shouldn't you be happy about a fast release cycle that brings you something you want?


The bottom line is that camera bodies (and, despite what others claim, I believe lenses, too) aren't really investments. They rapidly depreciate in value, just like pretty much everything else these days. If you're price sensitive, don't buy the current generation, buy one or two generations back -- you'll still get a machine capable of producing incredibly images (if your skills are up to the task) at much more reasonable prices. 

#378077 Winter musings

Posted by dreifish on 23 October 2016 - 04:07 PM


Maybe you can read that from the metadata of the file. I do that in Sony Vegas Pro with an extension called Show Recording Data, but you there would be other free tools to do it outside of Vegas like EXIF Viewer(?). I guess maybe Adobe apps (Lightroom? P Pro?) show it in the file properties.


As to the main question, it's very difficult at the moment to make recommendations. I'm not happy with the GH4 for run-and-gun style underwater shooting, which is what I do, for many reasons. I badly want to go to Raja Ampat but I actually turned down a trip this coming February partly because I thought I would be frustrated by the camera. And I think that would be true for most of the "stills" cameras that have video features.


On the other hand, the GH4 is great for tripod-based macro video, once you've worked out a working focus procedure. So it depends what you want to shoot.


The camera that interests me most for wide angle is still the Sony Z100 in a Gates housing with a SWP44 lens that Josh Jensen shot this with. A 4K 60p ENG camera with a built-in lens, ND filters, proper auto-focus, nice white balance, proper zoom, worldwide support etc.. But it's so old now! Maybe we'll get a Z200 one day. Who knows...



Fully agree on this Nick -- I'm not sure how much of it is the camera/housing/lens/lights combination as opposed to Josh's obvious mastery of it and whatever post-production he's doing that makes the difference, but his  footage is excellent -- both in terms of colors, sharpness, focus, and stability.  Aspirational I would say.


I'm not convinced it could be replicated with a Sony A7RII, GH4, or other similar DSLR setup, including a housed Canon 1DXII ($11000).


Of course, the Z100 ($4500 new, $3750 used) + gates housing ($7250) + SWP44 lens ($4300!) at $15000+ starts to put you firmly in Sony FS7 ($8500 body + $6400 aquatica housing + $2000 dome = $16900 + lenses) or even Red Raven territory ($10k body, $10k nauticam housing, 2k dome = $22000 before lenses). And, from the specs, it's a larger, heavier camera setup than the FS7 or Red Raven.


Which begs the question -- why did Josh pick the Z100 over an large sensor, interchangable-lens raw-capable FS7 or Red setup? I'd be curious to hear his answer. Perhaps it's the versatility of the 20x zoom-through par-focal lens with the SWP44 port allowing you to go to a full 110 degrees at the wide end. That sure would be sweet to have for run-and-gun type shooting. Does it outweigh the benefits of RAW recording and the higher dynamic range of a large-sensor camera? I don't know. Perhaps for his work, it does. I'd be really curious to hear Josh's take.

#378018 Island of the Gods - Bali

Posted by dreifish on 22 October 2016 - 03:19 AM

Awesome stuff, Dustin!

#378010 Color Correcting Purple Water

Posted by dreifish on 21 October 2016 - 05:10 PM



It's actually a pretty easy correction using the blue color vector in the 6 vectors panel of Color Finale Pro plugin for FCPX, pushing the hue of blue from magenta towards cyan and increasing the saturation a bit. I do the same thing with the HLS panel in Lightroom for stills, so I suspect something similar can be done in Adobe Permiere or DaVinci Resolve, but I'm not experienced enough with that software to explain. Here's the exact correction:


First, adjust the blue vector, which fixes the water column:


Screen Shot 2016-10-22 at 8.58.33 AM.png



Then fine-tune white balance with the color wheels. 


Screen Shot 2016-10-22 at 8.58.43 AM.png

#376888 Sony a7s II underwater use -- All parameters

Posted by dreifish on 10 September 2016 - 04:53 AM

Well the deep shot is so defective with its magenta color that I don't think anything could help it.  The question is, if it had been shot in a sLog profile, would it be easier to correct?


Thanks for taking the time to do that.


No, it would be even harder to correct. SLOG is meant to solve issues with dynamic range -- i.e. a very contrasty scene where the brightest part of the image and the darkest parts of the image are more than 7-8 stops apart. The scene you filmed isn't one of those situations. It's easy to tell -- just put up the histogram when recording the video or a waveform monitor in your video editor. Most likely, when shooting with no picture profile, you'll find that neither your blacks nor your whites are clipping. So you can easily represent all of the image in 7-8 stops of the standard no picture profile. All SLOG will do is compress those 7-8 stops of contrast into 3-4 instead.  


After further testing over the past two days, I've basically found no situations where you NEED more than 7-8 stops shooting ambient light underwater. Think about it -- all those particles in the water strip away contrast resulting in a very flat image. That's why the most important rule of underwater photography/videography is to get as close to your subject as possible. The only situation where the scene has greater contrast than that is if you're shooting directly into the sun AND you're trying to preserve detail in the highlights AND the shadows (as opposed to just silhuetting whatever you're shooting against the sun). How often do you find yourself doing this with ambient light underwater?


SLOG only helps you preserve more luminance detail. It does not help you preserve more color detail. In fact, because it compresses the luminance range, it actually preserves less color detail. So no.. color correction of SLOG footage is never going to be easier than color correction of non-slog footage. 


I will try to post some more of the tests I've done, including some UAWB tests in the 10-12 meter range and using all the different picture styles to see which creates the best colors over the next few days (or weeks.. I have a busy week next week). In the meantime, I'll leave you with another screen grab from a video shot today. No picture profile, picture style standard, 3m, underwater auto white balance. 20160910-.jpg