Custom white balance

Adow2

Adow2

Messages
668
Name
Alan
Edit My Images
Yes
HI all, I'm sure this topic has been discussed before. However I have done some searching and can't find the answer to my particular questions. I've just bought a set of wb cards. They're the size of a credit card. There's white, gray and black. Do I set my custom wb using the white or gray card? I keep reading that the gray is for exposure?? Then what is the black card used for? When trying to take a shot of the card I can't seem to get auto focus to set on the card. How much of the card should be in shot to take a custom wb from?

Apologies for all the questions, I don't know if I've jumped the gun a little in my learning curve worrying about custom wb!

Cheers
Alan
 
Adow2 said:
HI all, I'm sure this topic has been discussed before. However I have done some searching and can't find the answer to my particular questions. I've just bought a set of wb cards. They're the size of a credit card. There's white, gray and black. Do I set my custom wb using the white or gray card? I keep reading that the gray is for exposure?? Then what is the black card used for? When trying to take a shot of the card I can't seem to get auto focus to set on the card. How much of the card should be in shot to take a custom wb from?

Apologies for all the questions, I don't know if I've jumped the gun a little in my learning curve worrying about custom wb!

Cheers
Alan
Click to expand...

You have rather ;) For custom white balance, see camera handbook, it will tell you to use a piece of white paper. It's really all you need - any neutral grey/white target. Wedding togs sometimes use a white table cloth. It will get you close as makes no difference.

Those little card jobbies, of marginal usefulness IMHO, is you include them in an image and can then read white balance and tonal range from them in post processing. Kind of thing studio photographers might use (though I do a lot of studio work and have never felt the need...).
 
Adow2 said:
HI all, I'm sure this topic has been discussed before. However I have done some searching and can't find the answer to my particular questions. I've just bought a set of wb cards. They're the size of a credit card. There's white, gray and black. Do I set my custom wb using the white or gray card? I keep reading that the gray is for exposure?? Then what is the black card used for? When trying to take a shot of the card I can't seem to get auto focus to set on the card. How much of the card should be in shot to take a custom wb from?

Apologies for all the questions, I don't know if I've jumped the gun a little in my learning curve worrying about custom wb!

Cheers
Alan
Click to expand...

You camera is set to read 18% gray so what your doing is showing you camera what the true 18% gray is under certain lighting conditions. Its a baseline so to speak. I used it and found that it can help in certain conditions like an overcast day. But 95% of the time the camera get the balance correct.

About the cards you are using. They are really to small to be useful. If you were shooting a book laying on the ground you would set the card beside it so the card gets the same light as the book. This will show the camera what 18% gray is under that particular light. The card needs to fill the frame so that it does not get any other lighting condition in the shot (from the sides), just the gray card in that light. Yes you can use spot metering but I found it not to be as accurate. It's very difficult to hold that small card where you need it to be in most cases and fill the frame.

As far as focusing goes, you do not need it when you are setting your balance. Just turn off auto focus, fill the frame with a gray card under the light you will be shooting in and shoot.

Sorry this is so long. Hope it helps.
 
shaylou said:
You camera is set to read 18% gray so what your doing is showing you camera what the true 18% gray is under certain lighting conditions. Its a baseline so to speak. I used it and found that it can help in certain conditions like an overcast day. But 95% of the time the camera get the balance correct.

About the cards you are using. They are really to small to be useful. If you were shooting a book laying on the ground you would set the card beside it so the card gets the same light as the book. This will show the camera what 18% gray is under that particular light. The card needs to fill the frame so that it does not get any other lighting condition in the shot (from the sides), just the gray card in that light. Yes you can use spot metering but I found it not to be as accurate. It's very difficult to hold that small card where you need it to be in most cases and fill the frame.

As far as focusing goes, you do not need it when you are setting your balance. Just turn off auto focus, fill the frame with a gray card under the light you will be shooting in and shoot.

Sorry this is so long. Hope it helps.
Click to expand...

Yes, but you're confusing white balance with exposure.

For white balance, you just need any neutral target, with equal quantities of red, green and blue. It can be any shade or grey, or white, and so long as it's not under-exposed (and full of noise) or over-exposed (and possibly blown) then that's fine.

For exposure, you don't actually need dead neutral grey and some 18% grey cards are not quite neutral (eg Kodak) but they are exactly 18% reflectance. That's the recognised mid-grey standard and should put a spike right in the middle of the histogram. (Some cameras are calibrated to 15% grey or thereabouts, but 18% is the universal reference.)

From this you can see that a grey card that is both neutral and also 18%, would serve both purposes.

BTW, with Canon custom WB, the target only needs to fill the centre circle.
 
HoppyUK said:
Yes, but you're confusing white balance with exposure.

For white balance, you just need any neutral target, with equal quantities of red, green and blue. It can be any shade or grey, or white, and so long as it's not under-exposed (and full of noise) or over-exposed (and possibly blown) then that's fine.

For exposure, you don't actually need dead neutral grey and some 18% grey cards are not quite neutral (eg Kodak) but they are exactly 18% reflectance. That's the recognised mid-grey standard and should put a spike right in the middle of the histogram. (Some cameras are calibrated to 15% grey or thereabouts, but 18% is the universal reference.)

From this you can see that a grey card that is both neutral and also 18%, would serve both purposes.

BTW, with Canon custom WB, the target only needs to fill the centre circle.
Click to expand...

I'm sorry you are correct again Hoppy. I always do that for some reason. I really hope I did not confuse the issue to much.
 
Thanks for the replies! Glad I only spent a couple of quid on the cards......think I am jumping the gun a little!!

Think I've been spending too much time reading about photography rather than actually doing it! 😝😝

Ta
Alan
 
You must log in or register to reply here.
Back
Top