Should extension tubes change exposure?

Shooting in macro mode, techniques, tips & tricks

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Should extension tubes change exposure?

Unread post by BrianS » 20.12.2012 14:37

Have just started shooting diamond rings with my Canon 1DX and my EF 100 2.8, previously used my 50D. So far everything great however....

Because the 1DX is a full frame, I can't fill the frame with a ring now at the closest focus distance like I could with the 1.6 crop 50D.

So... I popped on my extension Kenko/Canon tube set totalling 66mm - much better, but when the stack finished I saw a big change in brightness from the first to the 40th shot - at least one maybe two stops ??? Repeated the stack - same thing -, removed the tubes back to normal.

I've been doing this for a few years now - first time using tubes - lighting is the same - studio flash and fills all on manual etc and camera settings all fixed of course.

Like to hear your thoughts.

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Stas Yatsenko
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Re: Should extension tubes change exposure?

Unread post by Stas Yatsenko » 24.12.2012 12:54

To tell the truth, I am not a big expert in optics. But... If you move light source (lens) from the censor you should get less light, this this quite logical. Because lens now projects the image on the larger area. You get higher magnification because censor now captures only part of the scene. But this also means it captures only part of the light!

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