White Balance

fatrip

Yup That Stuff
hey guys i was wondering, in a few different post people are saying to use a white object to customize the WB on a DSLR, why you would use a white object instead of a gray card?
 
"Because you want the white to look white, not grey"
i am guessing you are either being funny or dont know what a gray card is...lol..

"many cameras "custom" WB mode expects to meter off of a 100% white card"

that is interesting i had been told and read that it meters it off of the 18% reflective gray.

i believe you guys so dont get me wrong. but i dont understand why. beerguy, i was wondering if you could try and explain it to me why we would use a gray card outside a fisht tank but a white card in the fish tank???
 
<a href=showthread.php?s=&postid=12645555#post12645555 target=_blank>Originally posted</a> by fatrip
"Because you want the white to look white, not grey"
i am guessing you are either being funny or dont know what a gray card is...lol..


A little bit of both... :lol:
 
<a href=showthread.php?s=&postid=12645555#post12645555 target=_blank>Originally posted</a> by fatrip
had been told and read that it meters it off of the 18% reflective gray.

Sure.


Your light meter does expect the whole world to be grey. It uses that assumption when recommending an exposure value. WB is different. WB is, like the name suggests, telling the camera what shade is white.

When we shot film, you bought film for the color temperature that you were shooting; indoor, outdoor, tungsten..... That's really the same thing that we're doing when we set a custom white balance.
 
hummm, see that is backwards from how it was explained to me in a class.

the way i was taught and explained to is that the metering for exposure would be going off the same metering as the white balance.
so if that was correct wouldnt the recommended exposure be off by a bit if you were going off a white card instead of a gray one.

i dont want to sound like i am not believeing you but i am just trying to grasp it because i was taught and understood it a different way. thanks :)
 
Setting white balance is a different operation and has nothing to do with exposure (other then helping the camera know what gray looks like under your light).
 
so then if the exposure metering goes off of 18% reflective gray and you use white for customizing the white balance instead of gray wouldnt the exposure be off becuse it thinks the white is gray?

:edit or would it be off so little that it would not matter really?
 
Nope.


It doesn't think the white is gray. You've still got the two things tied together and their not. Exposure metering is expecting grey. That happens before the shot.

WB isn't applied until after the shot is taken.
 
ok so one is independant of the other. then why would someone use a gray card in the first place?
 
To set exposure. You can use the grey target to meter from if you're in tricky lighting situation. For that to work the card needs to be getting the same light that your subject is getting.

Most grey cards also have white and black targets. I have one of these:

whibal.jpg


After the shot, you can use those targets in PS to set WB.

Add a curves adjustment layer and then use the three little droppers to set black, grey and white from the card.

ps_curves.jpg
 
OK I need to piggyback on this thread...This WhiteBalance thing is killing me...I have spent so much time reading about exposure "understand exposure" and also "digital photography" by Scott Kelby, I am getting great photos outside and even inside...so I thought I was ready for my tank I cannot get the blue out of my photos, I hate spending any time in front of photoshop so please help me...

I have a Nikon D70s and several nice lenses including the Nikkor 105mm Macro...

I think I need to...

1. take a white card and shoot a photo
2. Use that picture of the white card, go to the menu, white balance, select preset and select that picture of the card and then my camera will use that was my "white"..

Maybe I am just reading too much into this and I need to take the picture of a white sheet and try it...

Thanks

Jason
 
I usually choose a gray area of the rock in my tank or the sand when I WB on the tank. This seems to work well enough.

When I set the WB on my Nikons I need to put the camera in mode where it knows to set the white balance. I can't just "take a picture". But both of mine have WB buttons on the back of the camera. Not sure how to put the D70 into the mode to set the WB.
 
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