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AE Lock with variable aperture N zooms on Canon bodies

 
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tyr



Joined: 24 Jan 2007
Posts: 6

PostPosted: Wed Jan 24, 2007 10:38 am    Post subject: AE Lock with variable aperture N zooms on Canon bodies Reply with quote

The Contax N1 body had a horrible bug in its AE lock behaviour with variable max aperture N zoom lenses. It would not compensate for the change in effective aperture by changing the shutter speed if you zoomed out/in after you set AE lock. For instance with the 70-300/4-5.6 zoom, if you set the AE lock at 1/125 @ f/4 at the 70mm end and then zoomed out to 300mm, the effective aperture (as displayed correctly in the viewfinder) would automatically change to f/5.6, but the camera would keep the shutter speed at 1/125 instead of decreasing it to 1/60, which would result in a one stop underexposed picture. Zooming the other way round would result it one stop overexposure, etc.

I know that my friend's EOS 10D did not have this issue with his Canon zoom lens. I believe this was a bug in the Contax camera firmware and I would guess that the adapted Contax N zooms will not have this problem on Canon bodies, but could somebody please verify this? Thanks a lot!
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Thu Jan 25, 2007 1:50 am    Post subject: Reply with quote

Just tried this with the Vario-Sonnar 70-300/4-5.6 that I am selling on eBay. After AE lock on a EOS 1D, zooming changes both aperture and shutter speed. For example, at 70mm the reading was 1/50 f/4, and at 300 it became 1/25 f/5.6.
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tyr



Joined: 24 Jan 2007
Posts: 6

PostPosted: Thu Jan 25, 2007 9:43 am    Post subject: Reply with quote

Thank you very much for confirming this!
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