More white balance questions...

[Buoyant1]

Ok...I'm reading a lot about white balance...I guess my biggest question is
how FAR from the lens should you hold your "white" object in order to pick
up the lighting/color correction at the given depth? I assume that if you hold
it too close you won't pick up the "depth" you are shooting at, and if you
hold it too far away it could give a false reading also.

Which then leads to the NEXT question, how large of an object should you have for this?

AND what are the benefits of using gray vs. white? I don't use a slate, but
I've also heard that using the sandy bottom works....

Thanks for any help, I've learned a lot by reading through some of these threads, and hopefully, I'll be able to use some of the tips I've picked up!

 

[Taxgeek]

Hi there. Let's see.

How far to hold the "thing" - ideally, the same distance away as your subject. Obviously, that isn't always feasible. If you have white sand, that works well (so people say - we don't have white sand here, so I wouldn't know.

Re distance, remember that the color is lost as the sun's rays travel down through the water to your subject, then some more is lost as it travels through the water from subject to camera. Since you're diving, and not snorkeling, the distance from surface to subject is so much larger than the distance from subject to camera that error you introduce by not putting the white balance "thing" the same distance away as the subject is pretty minor.

Object: Needs to be large enough to fill the frame at whatever distance you're holding it at. I've used a 6" dive slate, but I currently wear a white dishwashing glove on my left hand and use that. Some people attach the slate to their housing in various ways, or get one of the wrist mounted slates. White sand, of course, is supposed to work really well too if you have alot of that handy all the time.

Gray v. White: no difference as far as I know. The white balance calculation senses color, so any shade should be fine. White seems to be what most people like, it's hard to find a neutral gray object other than a gray card. I think they do make underwater gray cards though, for the video world.

Good luck, and white balance often! ;-)
Taxgeek

 

[friscuba]

Ok...I'm reading a lot about white balance...I guess my biggest question is
how FAR from the lens should you hold your "white" object in order to pick
up the lighting/color correction at the given depth? I assume that if you hold
it too close you won't pick up the "depth" you are shooting at, and if you
hold it too far away it could give a false reading also.

Which then leads to the NEXT question, how large of an object should you have for this?

AND what are the benefits of using gray vs. white? I don't use a slate, but
I've also heard that using the sandy bottom works....

Thanks for any help, I've learned a lot by reading through some of these threads, and hopefully, I'll be able to use some of the tips I've picked up!

I'm not the know all on this topic as I've only been playing with the white balance for several dives recently, but the results are great so far. I've been using a white shop towel, the kind you can get 30 of for a couple bucks at Costco. It doubles as a work rag so it's not even all that pure white anymore. I kind of just throw it out there and click on it, sometimes it's wrinkled, sometimes in direct sun, sometimes partially shaded, whatever, it still turns out quite well. It'd be cool to weight one side and have my buddy hold it still while I back up and use the zoom to give it a try from as far as possible to see teh results... I'm usually only a foot to foot and a half from the towel. It's a great tool, even with imperfect methods.

 

[bladephotog]

I use my wrist slate. I just make sure the frame is filled. Works pretty well.

 

[Buoyant1]

And just to confirm what I think read somewhere else...if you're going to use the flash, do your WB WITH the flash.. if not don't use the flash..right?

I'm going to try this next week in Key Largo...

Thanks for all of the help!

 

[Taxgeek]

Well, actually, I think most people shoot in auto WB when they're using flash. Or you could just try out all the preset wb points on your camera (daylight, fluorescent, cloudy, etc.) and see which works best with your flash. Easier than having to auto WB all the time, at least if you're not switching back and forth between flash and no flash every shot.

At least that's how I understand it.

 

[cinder4320]

I'm going to try this next week in Key Largo...

Maybe we'll be trying our new cameras at the same time. I'll be in Key largo from the 7th to the 11th and using my new Canon A620 and housing for the first time. Good luck!

Miranda

 

[Jeff Toorish]

White balance and Gray Card are not the same thing. In digital photography, the camera knows what white is and balances color accordingly, regardless of the light source. WE tell the camera, this is white under tungsten light and the camera sets itself...or you use a white card and create a custom white balance.

Gray cards come from film photography, specifically black and white, although there were useful with color film too. The gray card isn't really designed to balance color, it's used to set exposure. All film camera light meters (and hand held meters) are set to register 18% gray, about the middle of the scale from pure white to pure black. By using a gray card at a certain light level, you were essentially setting the exposure calibration. And from there you could open or close the apeture as needed to get the proper exposure.


You can't use a gray card to white balance...just as you can't use a white card to find 18% gray. (Althouh in post processing, you can use neutral gray (18%) to help with color balance.)

Jeff

 

[Buoyant1]

We'll be just missing each other. I'll be diving the 5th and 6th (Going out with Blue Water divers) I'll wave when we pass on the highway, I'll be the one crying!

Maybe we'll be trying our new cameras at the same time. I'll be in Key largo from the 7th to the 11th and using my new Canon A620 and housing for the first time. Good luck!

Miranda

 

[Buoyant1]

One more quick question...(The manual isn't too horribly explicit about it)

(and we're talking about a Canon a80)

Once I set the white balance...if I go back into the "AUTO" mode will this keep the setting, or go back to an auto setting?

If not...what's the best "mode" to keep the camera in for changing setting on the fly?

I'm figuring this trip with the camera is going to be the serious trial and error experience, if I get decent photos, then I'll be ahead of the game...if not, at least I'm not paying for processing!