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Interceptor121

The importance of underwater white balance

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I found the time to do a little write up on underwater white balance that includes some of the techniques I use

Hopefully this is useful to most people out there. I have focussed on GH5 picture profile but I guess other camera won't be much different

 

https://interceptor121.com/2019/09/24/the-importance-of-underwater-white-balance-with-the-panasonic-gh5/

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Great article.  I've been using an arm-mounted underwater slate to do Custom WB, but will look into using a WhiBal card instead.  Do you have a picture of how you attach the card to your BCD?  Thanks!

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5 minutes ago, Deinonych said:

Great article.  I've been using an arm-mounted underwater slate to do Custom WB, but will look into using a WhiBal card instead.  Do you have a picture of how you attach the card to your BCD?  Thanks!

I use a clip with a soft edge as otherwise it cuts the card but you are making a good point I will add a picture

I just heard Keldan is coming up with a checker card and I will receive it for prototype testing

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Do u have that picture? Also, have u played with having the lut already in your camera/monitor so you will see what it looks like right away or might this be a problem going deeper perhaps?

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6 hours ago, Pajjpen said:

Do u have that picture? Also, have u played with having the lut already in your camera/monitor so you will see what it looks like right away or might this be a problem going deeper perhaps?

I am abroad for work at present so I had no time to update the post I will do that when I get back

You can definitely load the LUT if you have a monitor I do not have one at present however the settings for CineLike D are just Noise Sharpness and Saturation -5 nothing particular and CineLike is REC709 compliant the highlight clip is at 100% not at 75% or 90% like VLOG or HLG so I am not sure there would be any benefit.

In terms of contrast cinelike D gamma curve is stretched but it is not a difference between night and day like VLOG.

Once you get the LUT on the camera profile this is just a baseline for grading the contrast is not affected so you still need to work it to bring it where you want it to be. I use the Pro Quickies and find the Film settings to work quite well in most cases.

Using a filter naturally increase saturation so also on that front I tend to use the automatic setting for color in FCPX pro after the LUT is applied and then finally I look at the LUMA and Saturation curves for clipping. I have to say almost never I clip the highlight as I tend to underexpose -2/3 to -1 as recommended by magic filters however this has to be checked now that the GH5 has a highlight priority mode as this may not be necessary anymore

When I have the pictures of the white balance card lanyard I will update this post to let you know

 

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6 minutes ago, John Doe II said:

And if one is shooting RAW? While always good to W.B its not totally needed for RAW - right?

John we are talking video here not stills so WB is required. I do not know what RAW is inside a camera like BMPCC 4K however I doubt it is uncompressed RAW and therefore white balance will certainly not hurt there either

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Interceptor, 

I bow to your knowledge and understanding of all this. I have read many times that it is always useful to get a W.B but its not totally needed. Proper exposure is def needed. 

My understanding of RAW is that the colour balance is just metadata.

it's a complex subject for sure. I think it cant harm to W.B for RAW but its 100% needed for a cooked in codec. As far as I know (I dont follow the GH5 stuff) the GH5 has video codecs that one chooses.

To me its all about RAW. I dont care about the work to colour balance it  and the storage space. It takes far more to get to a dive site then it takes to colour balance footage later on. Just my 2c on how I see things.

 

P.S But love your articles and in depth knowledge that YOU FREELY SHARE HERE.

Edited by John Doe II

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It is hard to correct white balance in post if the actual white balance used while shooting is not correct.

If using RAW (as it happens for both stills and video), simply applying a correction shifts the whole color spectrum. So unless WB and lighting are as close as possible to "correct" at time of capture, if you attempt to get pleasing reds, the spectrum shifts and your blues go funky and vica versa. 

Local WB corrections are certainly possible for stills (and I would guess for RAW video too?), but it is really hard to get them looking good. This would be complicated by the movement of parts of the video scene, which would potentially require re correcting each frame!

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I posted this specific point in the video section because I didn’t want it to become a generic discussion on white balance yes or no for RAW images

The video workflow is totally different from stills and even if you white balance you still perform adjustment in the final stage of your edit so clearly having footage that can withstand color manipulation helps however raw video is not mainstream and even if you can get to 50000 K in post if you were too off during capture it looks weird exactly as it does with still images and this is one of the reasons I am advocating the use of filters in ambient light shots and white balance in capture

So am aligned with what Adam says in terms of not being too far off whilst in terms of correcting in post it is not an issue because you typically have homogeneous clips that are short in duration and this is just the way it works in video



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Finally I had the time to get a picture of the white balance card and lanyard sorry it tool so long

On 11/12/2019 at 12:37 AM, Pajjpen said:

Do u have that picture? Also, have u played with having the lut already in your camera/monitor so you will see what it looks like right away or might this be a problem going deeper perhaps?

 

WhibalLanyard.jpg

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Great write up.   I am going to be with the bulls today in Playa Del Carmen, Mexico.  unfortunately they do this dive at 80-90 feet 25 meters.  In the past i have followed your advice including getting the WWL-1 and  14 -42 lens.  I'll probably just use a manual white balance at 30-40 feet then do a black and white since after reading your post there is probably no point trying to get a manual white balance at 80 feet as it will crush the blues and make the image grainy, correct?

 

If i get close enough I  do have the 18000 lumen video lights depending how many photographers on the dive I'll use those sparingly.  

 

I may be down here a couple more weeks i may be able to order a filter and try another day.  What do you sugest for that depth and would you filter it then do a manual white balance with the filter on at depth? 

 

Also you have mentioned before that you don't want to go down below F11 and that makes sense with dome port but i have been told by the cave guys that you can shoot much below that with the WWL-1 wet lens because it is not a dome but actually a lens  and not having to fight the corner sharpness from the distortion of the dome.  Thoughts?   Does that make any sense?

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15 minutes ago, gearbow_36218 said:

Great write up.   I am going to be with the bulls today in Playa Del Carmen, Mexico.  unfortunately they do this dive at 80-90 feet 25 meters.  In the past i have followed your advice including getting the WWL-1 and  14 -42 lens.  I'll probably just use a manual white balance at 30-40 feet then do a black and white since after reading your post there is probably no point trying to get a manual white balance at 80 feet as it will crush the blues and make the image grainy, correct?

 

If i get close enough I  do have the 18000 lumen video lights depending how many photographers on the dive I'll use those sparingly.  

 

I may be down here a couple more weeks i may be able to order a filter and try another day.  What do you sugest for that depth and would you filter it then do a manual white balance with the filter on at depth? 

 

Also you have mentioned before that you don't want to go down below F11 and that makes sense with dome port but i have been told by the cave guys that you can shoot much below that with the WWL-1 wet lens because it is not a dome but actually a lens  and not having to fight the corner sharpness from the distortion of the dome.  Thoughts?   Does that make any sense?

Hi Mike. At 80 feet I would use your DivePro lights at full power if needed. If you are on sand maybe you have some reflections and ambient light but still off the range of a filter.

In terms of f/11 that is the smallest aperture I would use. On the 14-42 MK II lens it starts at f/3.5 then f/4 all the way to f/22. Where f/22 is a smaller aperture of f/11 (larger f number means smaller aperture). The sweet spot is f/5.6 or f/8 f/4 is soft f/11 is limit to lens diffraction and still good. f/13 f/16 f/22 try never to go there.

For bull sharks at depth you will have to compromise between f/4 and f/5.6 

Not sure how close do the bull shark come if they are not that close there is an alternative option to use a rectilinear lens not too wide and then you can go all they way to f/2.8

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29 minutes ago, Interceptor121 said:

Hi Mike. At 80 feet I would use your DivePro lights at full power if needed. If you are on sand maybe you have some reflections and ambient light but still off the range of a filter.

In terms of f/11 that is the smallest aperture I would use. On the 14-42 MK II lens it starts at f/3.5 then f/4 all the way to f/22. Where f/22 is a smaller aperture of f/11 (larger f number means smaller aperture). The sweet spot is f/5.6 or f/8 f/4 is soft f/11 is limit to lens diffraction and still good. f/13 f/16 f/22 try never to go there.

For bull sharks at depth you will have to compromise between f/4 and f/5.6 

Not sure how close do the bull shark come if they are not that close there is an alternative option to use a rectilinear lens not too wide and then you can go all they way to f/2.8

Thanks for the quick reply,  I am hoping to get nice a close :) Although it is the beginning of the season crossing fingers also not to get skunked !

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