Underwater Bubble Blowers User Group Thread NEW

[Pawel Achtel]

Yes, if you're on the spot, the main thing I'd be looking at is the reds in your histogram in relation to the others.

Yes, reds and blues. Blue is filtered out in "green" water. You would assess the colour imbalance by measuring the EV drop and chose the filter accordingly.
What helps is to have the filter compensation effect measured before hand for each filter that you have. Of course, you do it with the trusty (raw) channel exposure meter too without even getting wet.

[Pawel Achtel]

So, Pawel, now we know why Jannard responded personally on this thread, threatening to shut it down. And why you thanked him forthwith. You petitioned him personally, alleging grievous personal insult, aggravation, and commercial disadvantage? Did Jim even bother to read the thread?

The innocent attacked, is that your stance? .

none of the above. It would be naive to think that Jim would respond on the forum and removed selected posts without reading them first. It is a professional forum about film making and trolling or personal remarks are not accepted. It is very easy to understand.

[Paul Russell]

I'll take sone reds and oranges and we'll run a test. The DOP wants narrow DOF anyway.

[Johnny Friday]

Ok....now back on track to the discussion at hand. Apologies for tackiness Mike.
JF

[paulherrin]

Pawel, thanks for sharing the resources, I'll see if I can look over some when I get a minute to breathe.

I'll take sone reds and oranges and we'll run a test. The DOP wants narrow DOF anyway.

Paul, there are possibilities to get the narrow DOF look in post that may save you time and money in production. I can see a lot of reasons not to try it in the original capture. You can always defocus an image (or parts of it)... Obviously, if you can get it in the shot you should get it - but I would build in more than enough cushion for missed focus. I'm sure you know the challenges at hand, but I'm just sayin'. Not commenting on the creative decision, just the practicalities of where the look might be applied in a cost-effective manner. That will depend on the specifics of your project, but it's something to think about and possibly test out.

[Jeff Whitehurst]

Yes, if you're on the spot, the main thing I'd be looking at is the reds in your histogram in relation to the others.

Thanks, that seems like a consistent way to monitor the shoot. Sounds like a quick assessment of the histogram would easily help determine the correct filtration (if any) for the conditions.

Your work on the Galapagos Doc looks great BTW, thanks for sharing your experiences. Any chance you could post some before and after underwater stills? If not I'll hope to see some of your workflow on the behind the scenes on the DVD :)

[Jeff Whitehurst]

Jeff,

You are spot on on all accounts. An experienced cinematographer would estimate the type and strength of the filter depending on the environmental conditions at hand. It is much more accurate than trying to work out a generic formula as the variability of conditions are significant.

You are also correct that the channel raw exposure meter would be your friend to determine what type and strength filter would bring the image closer to neutral. All you need is a grey or white slate and a test dive.

I'm a big fan of colour correction filters and use them most of the time. In fact, I'm working on an internal (rear) filtration system for Nikonos lenses as we speak. Good fun.

Thanks for the insight. I should have added that I don't have much experience with underwater lights. In your opinion, would the same factors regarding environmental conditions still apply with artificial lighting, and how would that affect filtration choices in a RAW workflow?

[paulherrin]

Your work on the Galapagos Doc looks great BTW, thanks for sharing your experiences. Any chance you could post some before and after underwater stills? If not I'll hope to see some of your workflow on the behind the scenes on the DVD :)

you mean a little somethin' like this? ;)





i'll see if we can't scrounge some more up in the next week or so, thanks for the compliments - as i mentioned before, the credit really goes to the guys jumping in the water. they've seriously put a lot of dedication into this :)

[Jeff Whitehurst]

Nice! That's the shot I was hoping you'd show. Love how the orange tones pop out in the CC version. The spot lighting makes the diver look like a hero, dig it!

you mean a little somethin' like this? ;)





i'll see if we can't scrounge some more up in the next week or so, thanks for the compliments - as i mentioned before, the credit really goes to the guys jumping in the water. they've seriously put a lot of dedication into this :)

[Pawel Achtel]

Thanks for the insight. I should have added that I don't have much experience with underwater lights. In your opinion, would the same factors regarding environmental conditions still apply with artificial lighting, and how would that affect filtration choices in a RAW workflow?

Yes, they do. Artifical lighting is subjected to exactly the same filtration as ambient as it travels through the same type of water. The only difference is that the artificial light path is from the light source to the subject and back to the camera. This combined distance in combination with the actual water colour absorbtion index will determine the final colour imbalance.

If you are going to film sharks, the combined distance is often more than 5m, which means that you would use at least 2 stops of filtration just for the artificial light (night time) and even more if you mix it with ambient light (daylight). In geen water it may add another two or three stops as the filtration is more intensive than that of pure water. When filming a sea dragon, for example, the combined path will be only between 1m - 2m, so the filtration you would use would be relatively mild, about 1 stop or less.

Ideally, you would like to override most of the ambient light for the foreground subjects. This is easier said than done! I usually use 24,000 lumens of tungsten light and still struggle on a bright day. In practice, the actual light will be a combination of ambient and artificial and, depending on the proportions of those two, you would select a filter that falls in between those two.

Because of all the variability, dependance on the subject distance and depth, one would usually try to find a compromise filter that would get the colour balance closer to nutral in most situations. Then, fine tune it in post. The less you need to adjust in post, the better.