White background Q

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Eddie1

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Ed
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When photographing someone against a white background with lights on the background to get white out, what F stop over the person should the background be ?
Half stop or more ?

thanks

Ed
 
Eddie1 said:
When photographing someone against a white background with lights on the background to get white out, what F stop over the person should the background be ?
Half stop or more ?

thanks

Ed
Click to expand...
Depends how you're measuring it.

As an incident reading logic says it needs no more light than the subject it's white so it will show as white in the same light, but practically you might want to nudge above that.

As a reflected reading, it's about 2 stops, which is the setting people often repeat as correct for incident too.

If you overexpose the background you'll get lens flare and wraparound light on your subject (neither of those issues are fixable in post). If you underexpose it, you lose some of the whiteness, but if it's not too far under you can fix it in post.
 
As a reflected reading, about 0.7 of a stop when using digital, and then just adjust the whites in post processing. 2 stops when using negative film.
Incident readings don't really work for this unless the background really is pure white.
 
Hi Ed,

I take my polar white paper to 1.5-2 stops to get it to pure white on my camera. The actual f stop will vary given my background lights are old and showing it.

The key is to have enough space between your subject and background so you don't get any spill or wrap around and of course keep your subject out of the background lights.

The more space you have to work in the easier this is to pull off.

Try it a few ways in the space you have to work in.
 
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