Pure white background

[atomk]

I'm attempting to photograph clear & tinted glassware against a white backdrop using my Canon Digital Rebel. I'm using blue photoflood lights, assisted by the camera strobe (bounced off of white posterboard). My camera settings are ISO=100, Shutter=80, maxJPEG, Custom WB. With auto exposure, the picture background comes out gray. When I increase the exposure to get the background "whiter", the image washes out. Any ideas to solve this problem?

[jimsolt]

I'm attempting to photograph clear & tinted glassware against a white backdrop using my Canon Digital Rebel. I'm using blue photoflood lights, assisted by the camera strobe (bounced off of white posterboard). My camera settings are ISO=100, Shutter=80, maxJPEG, Custom WB. With auto exposure, the picture background comes out gray. When I increase the exposure to get the background "whiter", the image washes out. Any ideas to solve this problem?
The exposure setting should be made based on the light falling on the subject.White balance is probably not causing the bg problem. Do the colors come out right on the foreground objects? If so, the WB is correct.

In other words, take your meter reading on the subject, not the background.

A simplification, but the idea should be there.

Jim

[Jon]

I think you need to set this up for manual exposure and flash. Set up and light the glassware, figure the exposure for that, then crank up the light on your backdrop (not the glassware) a notch so it comes through white. Set it up manually so the background doesn't influence the exposure.

[peterdoomen]

Does the problem still exist when you take the pictures in RAW and set whitebalance afterwards in the RAW tool?

P.

[jimlp]

I think you need to set this up for manual exposure and flash. Set up and light the glassware, figure the exposure for that, then crank up the light on your backdrop (not the glassware) a notch so it comes through white. Set it up manually so the background doesn't influence the exposure.

I think Jon hit the nail on the head here. Your best bet is to meter the light for the subject and background seperately as you will need more light on the background to make it lighter/white. I do not know if you have the flexibilty needed with your setup, can you control the lighting as described?

[Wilt]

I agree, you MUST separately light subject and background. Light the subject only and meter that, and set the camera manually to that. Then turn off the subject light, turn on the background light, and just light intensity so that it is about 1.5 EV brighter, and the background will go white when you expose for the subject. Then turn on all lights to make the shot.

[DavidEB]

It's tough with glassware because the glass is transparent. if you meter on the glass but then increase the amount of light on the background, you might get a washed out image (as you mentioned). Solid-colored glassware or stoneware (pottery) is alot easier. Another issue might be highlights & reflections of the glass.

I'd suggest going the other way -- use a black velvet cloth floor & background, and light the glass at an angle from behind and above.

not directly related but there's some good stuff on photographing thru glass with flash here... >>>click me<<< (http://www.dg28.com/technique.html) and it might give you some ideas.

good luck,

[PhotosGuy]

Lighting Set-Up Links –illustrations of real world examples
http://photography-on-the.net/forum/showthread.php?t=66140
Table Top Studio:
http://www.tabletopstudio.com/documents/HowTo_page.htm