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03-01-2011, 06:11 AM   #1
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P30n compatible with Sigma 10-20mm f/3.5?

Hello all,

I was just wondering if my Pentax p30n film camera is compatible with the Sigma 10-20mm f/3.5 lens?

Thanks in advance!

03-01-2011, 06:25 AM   #2
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Try it, but don't try many shots. Film is expensive. I believe the 10-20 is designed for a crop sensor, auto focus camera, not full frame.
03-01-2011, 08:10 AM   #3
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A friend tried my Pentax DA 12-24mm on his old RICOH film camera a couple of weeks ago, it worked quite well although obviously the camera had no control of the apeture (constant F22) and also the image was a perfect circle in the middle of the negative.
03-01-2011, 12:24 PM   #4
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The most significant problem is the image circle. The lens was designed for the smaller digital sensor, so it won't cover the entire film area. You can see this in the viewfinder. Most zooms do start to cover the film completely if you zoom out, so you might get something useful. Even 20mm on film is really wide angle.

The second problem is controlling the lens. Obviously AF won't work on the P30n. But since the camera has contacts for electronic aperture control, Program mode does work. With this camera, you can't adjust the program at all. It will show you a P on the left of the viewfinder and a shutter speed it has chosen. It works like a Pentax-A lens set to A. A film camera with contacts and Av mode would allow more control.

Without electrical contacts on the camera (K or M series), the lens should have an aperture ring or you can only use it at its smallest aperture (highest number). You'd have to jam the aperture lever to get anything else. The light meter will read based on that smallest aperture.

Sigma lenses won't always autofocus on older film cameras with AF. They mention incompatibilities with the SF series on their web site.


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