Getting gray background using white paper

Started Jun 26, 2013 | Questions thread
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YonathanZ
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Getting gray background using white paper
Jun 26, 2013

Hi,

I am trying to take macro shots of jewelry using focus stacking. I know how to focus stack but my problem is with lighting - I do have CFL bulbs and tungsten ones and a light tent. There's also the DSLR's built in flash (which I don't ever use, but it's there).

Anyway, my photos turn out to be grey, as in, I can't get a pure white background. I am using A4 paper (not recycled, so it's "very white") as the background on which I lay the jewelry (necklace or whatever) but the result does not have a white background.

Here's an example of a photo using tungsten light from real close (500W projector about 15 cm above the subject) to rule out the possibility of lack of light.

Before I fixed auto balance with a gray card:

No WB.

And after WB using Lightroom:

After WB.

As you can see, I didn't use focus stacking here, it's just a single shot, without a tripod or anything, just to get the colors. Another thing you can see is that the paper looks more like recycled paper, while in reality it's very much white.

Since we can rule out lack of light (at least as far as how powerful the light is; I know I should use balanced light, around 5500K), I wonder what really causes the problem. BTW, the same problem occurs when photographing using a light tent (to diffuse the light).

I shot using Aperture priority mode, f/5.6, shutter at 1/125 (as set by the camera), spot metering (also tried evaluative metering, same thing happens), Canon T3i and a Sigma 105mm f/2.8 macro lens at 1:1 magnification.

Please advise what could cause the problem.

Thank you.

 YonathanZ's gear list:YonathanZ's gear list
Canon EOS 70D Sigma 50mm F1.4 EX DG HSM +2 more
ANSWER:
Canon EOS 600D (EOS Rebel T3i / EOS Kiss X5)
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