same settings same object same light but some output photos have different tones

[imri]

Hey, I am really confused.

I am using 4 philips daylight 150 watt continuos light. I have a tripod and I am using eos software to shoot the photos to eliminative vibration.

dslr settings in M mode is as follows:
1/400 F5.0 Custom WB, ISO 200, Standard Mode, No flash

I am shooting the same product for testing purposes (like 6 shots) in the same conditions but images have different tones.

These are all shot using the same settings:
http://www.fotokritik.com/ekler/4/4/...59a6d507cb.jpg

I would really appreciate feedback.

[TPF Sponsor]

[480sparky]

Having access to the metadata would help.

Is there a window nearby?

[Derrel]

Artificial light sources can give off different wavelengths of light as the alternating current powers the bulbs---this is NOT at all unusual. Your careful testing procedure shows different color tones, subtly, but clearly.

[Christie Photo]

Artificial light sources can give off different wavelengths of light as the alternating current powers the bulbs---this is NOT at all unusual.

Agreed.

AND... the output will vary over the course of thier lives. Are these fluorescent lamps? If so, you can expect some variance as they warm up.

-Pete

[imri]

thanks for your answers, actually i have found out that the fluorescent lamps flicker couple of times in 1/400 I set the exposure to 1/100 and the problem is solved.