After i have go through my photos from my first trip with the Magic filters I see that i could make it better next time

But I have still some questions. Especially becauce I am thinking to get a strobe but I feel I have not explore the potenciall off the magic filter to 100%
and with the new D200 maybe everything will look diferent


About White Balance

At Alexs webpage i have read everything about White balance and magic filters but i still have some questions.
Alex sugess we can use the hand or the subject itsself. I use a Grey card.
I hold the grey chard in front of my camera pointing on the direction where I like to take the photo. Sun is always behind me and I try light the grey card with the available light


Now my question is follow.

Offen the subject is very near or very far away (I am speeking always about freedivers like those in www.tripledepth.com )
The depth of the subject is offen not know but I must white balance before otherwise I have not time to take the Photo
So what I do is to go to 5 meters and White balance and then take photos between 3 - 7 meters


Alex say that we can white balance on the hand or the subject itself.

Is there not a direrence in the the distance? I mean the hand or the grey card is closer to the camera that a subject.

Then there is info about " sensibility off the camera can help) Alex do you mean lower ISOS if you are talking about sensibility?


I am shooting always in RAW + JPEG and off cource i know that I can adjust the white balance later but I hink it is not the same thing
First i see that its take a lot more off my time to find where i set the dropper for WB and then sometimes the temperature is to high - 10000 kelvin
Then I see that sometimes WB take away some detail or show some noice. Thats the reasson why i like to come as close as I can get underwater..


Any comments to this?

Lambis,

Review my first photos taken with the Magic Filter on my Canon Rebel XT here:

http://www.magic-filters.com/gallery/david/index.htm

I found shooting a zoomed in photo of the sand at the approximate depth I wanted to take photos worked well. After practice I could shoot a photo, select that photo for my white balance reference in two button pushes and be ready to shoot in about 10 seconds or less.

If I went deeper and came up to a slightly shallower depth (maybe 3M shallower) I DID NOT white balance again. This resulted in slightly warmer images right out of the camera. I did find that underexposing 1/3 - 2/3 of a stop seemed to give me a bit more latitude to post process and not lose highlights. This could be my particular Canon camera, using Matrix metering or other reasons. (????)

Anyway, I think carrying a white slate, grey card or other item is a waste of time. For your free diving needs I'd simply practice fast shooting on the wet suit (if not black) or head and shoulder area of your diver. Then select that image quickly in your menu and shoot several frames before having to surface for air

Good luck!

dhaas

Hi Lambis,

It is always good to get as close as possible to the subject in underwater photography.

Regarding setting the WB. What is important is that you set a WB that is the same as that of your subject. If your subject is going to be significantly further from your camera than your grey card then go a bit deeper to set the WB.

Consider this example:


Here I set the WB on the sand in the foreground, recomposed and took this shot. This means that the optimum WB is in the foreground - and you can see that the colours fall away with distance. The corals in the middle distance do not have optimal WB (but if they did then the foreground would be too red)

If I was shooting a freediver here he/she would be further back in the frame and setting the WB very close to the camera would mean that the diver would be too blue. Instead I would go a metre or two deeper, set the WB there, then come back up and shoot the freediver. This would actually mean that any foreground would be too red, but as there is no foreground it doesn't matter.

Although in reality I would just set the WB on a grey card, shoot, and just sort the WB finetuning out in RAW conversion.

Hope that this helps.

Alex

Dhaas

Thats intresting with the use of a photo as reference for WB
I know the deep for all my photos (My freediving watch & Nikon are syncronise)
I will try this one day...

Alex, thanks man for the tip to go deeper and preeset the WB...
I have done it wrong all the time :-)

So if i like to shoot a freediver in 5 meters and the divers will be 2-3 meters away from me I just go to 7 meters and set the WB...


btw i can set the wb to the divers wetsuit if the suit is like the folow photo?




if i take WA shoots where the divers are 5-8 merers away must i dive deeper?

God help my lungs :-)

Its looks to me that with the type of frames that Lambis takes the WB is a big problem, usually he shot free divers in camouflage suites with almost no white areas in blue water without a sand floor, so where can you set the WB there?

On that Picture I would use the rope to set the WB. That is probably white.



Not true. Strong WB setting in camera is no less noisy than strong WB setting in photoshop. If anything, it is the other way around, the RAW should be less noisy. It is still great if you can get the WB right in camera, as it speeds workflow, but it has no consequence on the final product.

It would be really cool if the camera was able to apply analog WB correction in camera. Basically the camera would apply a different ISO setting to each of the different channels. Now that would allow you to eliminate the degradation to the red channel associated with strong WB settings and would require getting the WB close in-camera. But it isn't done that way, WB setting is applied by digital amplification and thus the in-camera setting is just a number stored somewhere in the RAW file and is of no consequence to the final quality of the raw file.

Arnon you are right

Most of the time the diver is covert in black neopren suti and there is no sand no reef or something else to make a WB
On the photo above the divers suit is o.k. but still not easly ..

Thats the reason that I have with me a lite Grey Card
The distange to the divers is a problem to
Below some screeshots form a DVD where you can see me while taking Photos.
Lock at the guy with the short shelves wetsuit Click to view attachment
You see that the situation is chainging all the time...

I think that i will do it like Alex say .. go deeper and WB on Grey card...

That would be cool indeed but it is not an option with current CCD technology and you'd still have to select different "color amplification" depending on depth + distance to subject. Another way to enhance the red light signal is to simply increase exposure or ISO setting. Of course that would overexpose the blue and green colours unless you use a magic filter, which aims to reduce the blue and green signal to the same extend as the red gets absorbed by water and so restore the balance. Since the red absorption depends on the distance that light travels through the water you'd need filters of different thickness to get perfect compensation. Luckily you don't have to be perfect. As long as you're close the white balance does the rest. In principle you should be able to push the use of magic filters to greater depth by using a thicker filter or a pair of filters, but at some point you will just not have enough light left to take the picture. (that's what makes William's wish to specificaly increase the ISO setting for the red channel so attractive as you're not throwing away light).

Although using the in-camera WB is convenient I don't think it is necessary or better than doing it later in PS. Especially if the "light path" distance changes all the time it would be nice if you could ask a program to calculate corrections for different distance estimates and then pick the one that looks best. I don't think such a program exists but you should be able to fake it with PS or the like. Here is how I think you should be able to determine the correction factors.

If 1 meter of water lets through only 1/2 the light at some colour then 2m will let through 1/4, 3m 1/8th etc. So if you compare the RAW image colour histogram of a grey card taken at the surface and, let's say 3m, you can calculate the attenuation of light per meter of water by taking the cubic root of the 3m/surface ratios for each colour. To find the attenuation for X meters of water you'd raise those numbers to the Xth power. To correct for the colour imbalance you'd apply the inverse of that number to the colour values of each pixel. By trying different values of X you can figure out what gives the most pleasing colour. If you're good with PS you may even be able to apply different corrections to a foreground subject and the background.
This was all without magic filter and will only work for relatively shallow depth. With magic filter the idea is the same, but part of the correction has already been applied by the filter so PS only has to do the remainder. By comparing RAW RGB histograms of a grey card shot on the surface with and without filter you can find the attenuation factors applied by the filter. You can then calculate what additional corrections are needed to get the values for X meters of water.

Having written all this I realize that using the in-camera WB really starts to sound attractive. However, assuming that the magic filter attenuation is always the same and the attenuation of 1m of clear tropical water is relatively constant as well, one should be able to come up with a table of correction factors for different values of X. For tricky situations like Lambis's shots it may be worth it. Of course, as long as you shoot RAW, you can still use the in-camera WB and only fall back to doing it the hard way when the result is not acceptable.

Bart

Bart is spot on. If you know exactly how deep the subject is and from diving in the area before you know the spectral attenuation characteristics of that water you can create the theoretically perfect filter.

The problem with this is that most subjects don't stay still and as photographers we don't want to stick a filter on our camera that restricts us to just one depth. Many of the early filters I tried were like this and operated only in a very restricted depth range. The key is not to have too much red as WB can't get rid of this if you come too shallow.
The Magic Filter is different and does make a perfect correction at any one depth, but is designed to help the camera by doing much of the correction work and also changing the light to make it easier for the cameras WB.

The Magic filter and in camera white balance technique is also designed to produce images straight from the camera. We don't all have time to spend ages in PS - and anyone who shoots a lot, quickly learns that workflow is much more efficient if you get images right in camera.

That said some cameras, e.g. Nikon D70, D2X, D200 make setting WB very easy. Really takes less than a second. While others are much more complex. If you have an easy camera it is well worth setting WB underwater for each shot, but if you don't you might be better to set it 2 or 3 times during a dive.

I wish I could show you all more of the images that I get sent by the magic users around the world. There are some absolute stunners!

Anyway I can see the Caribbean sea over my computer - and the sun is just coming up. Time to go out and practice what I preach!

Alex

I have try to fix my white bapabe to see how much i can improve my photos.

Sometimes when i have the white balance that i like i have very high noice on the water. then if the water is great the skintons and the diver have not good WB.

Below o photo with diferent White Balance and a 100% crop

original from camera



Rawshooter test 1



Rawshooter test 2



Capture pro




So what you are thinking.. the photo was only proccesed in the raw software. No Photoshop adjusments...

Lambis