Digital color balance and SCUBA diving
 

Should following a normal "custom" white balance process while at depth
result in accurate color capture? Any special considerations?

"Gerald" wrote in message
...
Should following a normal "custom" white balance process while at depth
result in accurate color capture? Any special considerations?


Adobe Photoshop will do a fairly good job of restoring what looks like
'normal' colour balance, its an approximation at best. You can make a grey
card for underwater use, this will improve the situation a bit. A strobe is
good for close work.

Email me offline for a sample of what Photoshop can do.

Should following a normal "custom" white balance process while at depth
result in accurate color capture? Any special considerations?

Actually, white-balance adjustments are designed specifically not to
give you accurate color capture, but rather to make the photo look
most like what the eye sees.

The eye (along with the mind) automatically converts most off-white
ambient light to white, so even in a large range of settings, white
looks white.

Film and digital sensors don't do this conversion automatically, so
they have to be set according to the lighting. Normally, this is a
good thing, but in caes of extreme lighting (sunsets, under water) you
don't want the lighting to look the same as it would it ordinary
daylight.


I would recommend shooting in RAW mode (if you can) and adjsuting
things later. Or if you cannot, shoow in a variety of WB settings.

-Joel

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Dr. Joel M. Hoffman wrote:
: I would recommend shooting in RAW mode (if you can) and adjsuting
: things later. Or if you cannot, shoow in a variety of WB settings.

... and still take a shot of a white/grey card to aid in the RAW conversion
later.

-Cory

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

Dr. Joel M. Hoffman wrote:
: I would recommend shooting in RAW mode (if you can) and adjsuting
: things later. Or if you cannot, shoow in a variety of WB settings.

... and still take a shot of a white/grey card to aid in the RAW conversion
later.

-Cory

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

My recent experience in Hawaii:
Even in depths of just 10meters red light is fairly well filtered out by the
water as far as digital cameras are concerned. Using flash underwater is
often a problem as waterborne particles reflect the light back at the
camera. Post exposure color correction helps but the color effect is rather
unrealistic but better than nothing.

(bmoag) wrote:
My recent experience in Hawaii:
Even in depths of just 10meters red light is fairly well filtered out
by the water as far as digital cameras are concerned.

Yep. Actually, I'd say that's true at even shallower depths - I do a
lot of skindiving with a digital, and there's a lot of blue/green.

Using flash underwater is often a problem as waterborne particles
reflect the light back at the camera.

Yep. "Backscatter." How much of a problem it is varies depending on
recent weather patterns (rain will cause runoff), time of day (morning
is clearer, before everyone gets to the beach) and how still the water
is, among other things.

Post exposure color correction helps but the color effect is rather
unrealistic but better than nothing.

Yep. Between haze at the volcano and lack of red light underwater,
I've gotten a lot of practice with correction. ;)

--
Dan Birchall, Hilo HI - http://hilom.multiply.com/ - images, words, technology

(bmoag) wrote:
My recent experience in Hawaii:
Even in depths of just 10meters red light is fairly well filtered out
by the water as far as digital cameras are concerned.

Yep. Actually, I'd say that's true at even shallower depths - I do a
lot of skindiving with a digital, and there's a lot of blue/green.

Using flash underwater is often a problem as waterborne particles
reflect the light back at the camera.

Yep. "Backscatter." How much of a problem it is varies depending on
recent weather patterns (rain will cause runoff), time of day (morning
is clearer, before everyone gets to the beach) and how still the water
is, among other things.

Post exposure color correction helps but the color effect is rather
unrealistic but better than nothing.

Yep. Between haze at the volcano and lack of red light underwater,
I've gotten a lot of practice with correction. ;)

--
Dan Birchall, Hilo HI - http://hilom.multiply.com/ - images, words, technology

On Thu, 24 Mar 2005 02:13:31 -0000,
(Dan Birchall) wrote:

(bmoag) wrote:
My recent experience in Hawaii:
Even in depths of just 10meters red light is fairly well filtered out
by the water as far as digital cameras are concerned.

Yep. Actually, I'd say that's true at even shallower depths - I do a
lot of skindiving with a digital, and there's a lot of blue/green.

There actually isn't enough red light to get a colour balance. Shoot
RAW.

Using flash underwater is often a problem as waterborne particles
reflect the light back at the camera.

Yep. "Backscatter." How much of a problem it is varies depending on
recent weather patterns (rain will cause runoff), time of day (morning
is clearer, before everyone gets to the beach) and how still the water
is, among other things.

Move the strobe a long way from the camera, and in extreme cases, well
behind the camera. Shooting mantas with a 10.5mm lens I have the
strobe about 18" behind and about 4' away from the lens centre.
Further is better!!

Pete S.

On Thu, 24 Mar 2005 02:13:31 -0000,
(Dan Birchall) wrote:

(bmoag) wrote:
My recent experience in Hawaii:
Even in depths of just 10meters red light is fairly well filtered out
by the water as far as digital cameras are concerned.

Yep. Actually, I'd say that's true at even shallower depths - I do a
lot of skindiving with a digital, and there's a lot of blue/green.

There actually isn't enough red light to get a colour balance. Shoot
RAW.

Using flash underwater is often a problem as waterborne particles
reflect the light back at the camera.

Yep. "Backscatter." How much of a problem it is varies depending on
recent weather patterns (rain will cause runoff), time of day (morning
is clearer, before everyone gets to the beach) and how still the water
is, among other things.

Move the strobe a long way from the camera, and in extreme cases, well
behind the camera. Shooting mantas with a 10.5mm lens I have the
strobe about 18" behind and about 4' away from the lens centre.
Further is better!!

Pete S.