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LOG Footage - Opinions on Underwater Use?

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So with the GH4 looking likely to be getting V-LOG-L (12 Stops) and with the new RX100 IV having S-LOG2

 

We will have more consumer options for shooting this supposedly nicer to grade footage.

 

I'm wondering if anyone has shot LOG footage underwater before? (Thinking Blackmagic, Arri, Red)

 

Wondering if its worth the hassle, if the colour fidelity is better (after post) or if you reverted to a more punchy profile in camera?

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Check this out:

 

http://www.eoshd.com/2015/08/gh4-log-converter-lut/

 

The people at EOSHD created a LUT to match the Canon 1DC color. I still don't fully understand the workflow/concept of LUT. If I understand it correctly, say if you really like the blue color that the Canon 1DC render, you can shoot with GH4 using the LOG profile, then run through the LUT and get the color of Canon?

 

RX100 IV S-LOG2 still need to be investigated. In another discussion, I read that the Sony A7S S-LOG fixed the ISO to 3200, ended up require the video shooter to use and ND filter otherwise everything get blown out.

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I was quite excited when I saw this, as the colours from Canon underwater I do really quite prefer compared to my GH4.

 

However it appears to be a take the relative flat profile (CINELIKE-D?) from the GH4, some predefined settings Andrew has configured in-camera (Sat/Const/Hue etc?) and an intermediate LUT (created by Andrew) to flatten the profile further to make it similar to C-LOG - to which you can then apply any number of LOG Gamma LUTs too, and in theory it will match similarly to C-LOG footage from a Canon with the same LUT.

 

All this to me, seems to chuck away colour information for then to try and bring it back.

 

To be honest I haven't purchased it yet - so I should really have a look at it first, before dismissing it completely...just seems too good to be true.

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It really depends on the base ISO you can work with.

If I recall correctly the black magic range works at around 800 ASA. The Sony Slog is 1600 to 3200 depending on camera. Not sure what Panasonic will be.

 

My main concern with this approach on micro four third cameras is the fact that the lenses work best up to f/8 in some cases f/11

 

If you push the ISO to 1600 or 3200 you then need a ND filter to get back to a range where the lens does not experience diffraction.

 

Generally working in a normal range may loose one Ev of dynamic range so you would be working at 11 Ev, I guess it really depends what that extra EV can do for you. Maybe for ambient light at depth this is an option but for normal depth and macro footage with artificial light not so much of an option.

 

I guess it is a matter of also understanding how much post processing workflow you want to endure and you like your final footage to look.

 

If your final result is similar or same of using a standard ITU/REC709 profile with some more contrast probably you have just wasted time

 

I have seen some footage shot with picture profile of sony cameras directly in video with some parameters altered for knee and slope that to me looks good most of times and requires no post processing

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My general feeling, mostly from what I've read rather than done, is that the higher quality the format the captured footage is, the more worthwhile it is to shoot LOG. For example...

 

8-bit 4:2:0 - Not really worth it. Better to shoot nearer to your final look (but ensuring no more contrast, saturation or sharpness than your final look so that if anything you are increasing these a little in post rather than reducing them).

 

10-bit 4:2:2 - More worth it

 

12-bit 4:4:4 - Definitely worth it because you can do so much to it without noticeably degrading the quality

 

If you shoot wide-angle with a very flat profile in 8-bit 4:2:0, you risk more banding in the water when you add contrast and stretch out the mid-tones.

 

Having said that, if it's free when it comes out I might try it on my GH4 (internal recording) to see how it goes.

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I think nick point is generally valid regardless of slog/vlog for color grading. If there is sufficient bitrate it is proven that higher bit color sampling resists much more to grading in post. However dynamic range has also to do with difference between dark and bright scenes which is only related to luminance and therefore applies to all color spaces. So even if you are not able to do color correction with an 8 bit color space you may still be able to recover more shadows and highlights with a log profile. Still I think higher bitrate recording is the key so the option is more appealing if you have an external recorder and not so much for recording in camera at limited bitrate and 8 bit color space.

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Nick is on the money I reckon, I have worked on a lot of productions where we have tested using the log on low end cameras 8 bit 420 and go pro's etc and find that you are way better to get the look as close to final delivery in camera. Yes you may gain a slight dynamic range advantage but you will also get serious banding and other issues. Shooting with higher end cameras log is great.

 

Edited by jonny shaw
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Just been looking into this as I've recently got a Sony a7 mk ii might shoot some LOG footage and have a play with it underwater and see what I think, I purchased a PDF which is basically just some settings for a picture profile as to try get Canon colours from Andrew's site and found it an absolute waste... maybe I'm not doing something correctly but even on land all my colours don't seem right it makes it worse then the original sony colours and from my understanding Andrew say's you don't need to grade it but his footage his got on his site definitely isn't straight out of the camera like his saying.. I'm a bit sceptical.....

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Your scepticism is well justified. If it comes to LOG footage you will find a lot of crap info on the net.... and people having found their way of skinning a cat: One being selling custom picture profiles, the other selling a ton of - to a large extend - dodgy and crappy looking LUTs.... But then that seems to be the game of the day. Particularly for filming Nature you really only need 2 LUTs to bring the color space 'back to normal' (ie Rec709): one for Slog2, one for Slog3. And I'd probably rely on the one provided by the camera manufacturer.

 

The only source of information that I found consistently reliable and informative is the page form a guy called Alister Chapman. www.xdcam-user.com. There is a ton of info about picture profiles, shooting LOG etc etc on Sony cameras. His key advice on LOG2/3 picture profiles: Don't tinker with them. Leave them as they are. The only thing to change is the SGamut color temperature (3200/4300/5500) depending on your shooting environment.

 

Would I shoot SLOG underwater? Only if I got solid experience and good results with it on land AND if I have a good monitor to check exposure. Exposing SLOG correctly based on a tiny 3.5inch camera screen underwater is virtually impossible - unless you have eagle eyes. If you got a 7inch monitor (DiveandSea, Atomos, Odyssey etc.) its a different story.

 

bubffm

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In my opinion, the use-case for log gammas is weak underwater. LOG gammas are there to allow you to squeeze a wider dynamic range into a smaller 8 or 10 (or sometimes 12) bit container. Whereas regular rec709 only lets you record around 7-8 stops of dynamic range, a log profile gets you closer to the 12-14 stops a camera's sensor might actually be capable of discerning.

 

However, in my experience, not that many underwater scene actually require such a dynamic range. All those particles in the water already sap the contrast, so most of the time you'll find your scene if you're shooting with the sun behind you has way less than 7 or 8 stops of dynamic range anyway. Same goes if you're using artificial light -- you should be able to light your scene so that it all fits into 7 stops of dynamic range. So the only time you really might appreciate the extra dynamic range of a log profile is if you're shooting into the sun or out through the opening of a cave or something like that. Not your typical use case..

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Hi has someone been able to use LOG's or something similar to minimize the post process work for underwater videos? I'm using the a6500 and find that a lot of post production color grading is needed. Specially for shoots over 45ft.

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I bring to file this old thread.... :)

I found these two GH5 videos shots 4K 400 Mbps (4:2:2 ALL-Intra a 10 bit). Picture profile V log L and Color Correction with Da Vinci Resolve 15 Studio

 

 

In this you can see before/after:

 

 

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I use cinelike D have not purchased the vlog key and even shooting the surface I don't get clipping. Am not planning on buying it either as I can see that cinelike has a lot of dynamic range sufficient to what I shoot
If I had the key I would run sow tests but frankly the camera has a lot of performance already if there is one area I would like to see improved is working around 3200 ISO for night photography nothing to do with diving

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Davide, 

I think he uses GH5S not GH5. The S is much better in the conditions he is shooting so I dont know if he would have the same result shooting the normal GH5

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No no. He is using a GH5.

I asked him if he made some test with plain cinelike-d to compare.

I'll let you know 

Bye

Edited by Davide DB

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Ok Davide, 

it is what it says in his video description that is why i  said so.

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1 hour ago, Lionfi2s said:

Ok Davide, 

it is what it says in his video description that is why i  said so.

You are right. My bad

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According to some geeks on the internet the main benefit of vlog is in the highlights not in the lower part of the grey where cinelike Ddoes better in the shadows which is what matters in dark shots 

Anyway I think all of the above would work when you shoot 10 bits at 8 bits probably does not make any sense to use log

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HLG has very good highlights recovery and its much more user friendly than VLOG L.

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HLG has very good highlights recovery and its much more user friendly than VLOG L.
I tried HLG extensively when I got the GH5 but struggled with proper grading as I do not have an HLG monitor. Of course you can look at the curves but the whole colour balance is different and at the end for underwater use I abandoned it
For land shots already white balanced it works great straight off the camera for me

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5 hours ago, Interceptor121 said:

I tried HLG extensively when I got the GH5 but struggled with proper grading as I do not have an HLG monitor. Of course you can look at the curves but the whole colour balance is different and at the end for underwater use I abandoned it
For land shots already white balanced it works great straight off the camera for me

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You can transform it to REC 709 using a LUT or color space transform node in Davinci Resolve. Thats the best option if you want to work with it and dont have an HLG monitor. To be honest if you just throw the footage to a REC709 timeline and the footage doesn't need drastic changes (the profile is not designed for that anyway) it will be fine for 99% of the viewers. If your shots are all balanced light shots it works fine. Remember that HLG is designed to have backwards compatibility with SDR. 

Edited by Lionfi2s
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I don't see anything in the below videos that would've turned out any differently had the footage been shot in an 8bit codec and the standard or cine-d picture profiles on the GH5, to be honest. There's no real highlight rolloff underwater except in rare circumstances where you're shooting up towards the surface (those shots don't look so natural in this footage, log or not) or blowing out your foreground illumination in mixed-light shots.

On 9/2/2019 at 6:32 PM, Davide DB said:

I bring to file this old thread.... :)

I found these two GH5 videos shots 4K 400 Mbps (4:2:2 ALL-Intra a 10 bit). Picture profile V log L and Color Correction with Da Vinci Resolve 15 Studio

 

 

In this you can see before/after:

 

 

 

 

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I don't see anything in the below videos that would've turned out any differently had the footage been shot in an 8bit codec and the standard or cine-d picture profiles on the GH5, to be honest. There's no real highlight rolloff underwater except in rare circumstances where you're shooting up towards the surface (those shots don't look so natural in this footage, log or not) or blowing out your foreground illumination in mixed-light shots.
 
 
I agree and actually in Bahamas I shot against the surface with a filter and there were no problems in cine like D 10 bits
10 bits does make a difference if you watch it at home but YouTube runs the blue giving banding in the tricky situations

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