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06-12-2013, 03:17 AM   #1
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Sigma lens (Canon mount) on Pentax body?

Hi there, I have just spotted a good deal on a used Sigma 100-300 F4 APO DG HSM lens. I am in the process of trying to track down a Sigma 50-500 lens in New Zealand to use for birding, but if it is possible to get the 100-300 working then I could save a fair bit of coin and maybe even get better IQ (thoughts?). Is it possible to get the 100-300 working on my K-30, or will I need to get back to hunting down a 50-500?
TIA

06-12-2013, 03:26 AM   #2
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No. The EF mount has a focal flange distance of 44.0mm. The K-mount has a focal flange distance of 45.46mm. Because the EF has a shorter focal flange distance you can adapt a K-mount lens to a Canon but not the other way around. An EF to K adapter would need to be optically corrected to maintain infinity focus (it would be a short teleconverter) and would need to have electronic control of the aperture. If such an adapter were made it would probably be as expensive as the price difference...
06-12-2013, 03:30 AM   #3
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Thanks for the quick reply boriscleto - back to the drawing board it is!
06-12-2013, 05:57 AM   #4
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QuoteOriginally posted by Snipsnap Quote
Thanks for the quick reply boriscleto - back to the drawing board it is!
The 100-300 is a great lens - if you've found it at a low enough price you might also consider picking up a last-gen canon body to pair with it, rather than keeping up the search for a 50-500. Just a thought!

06-12-2013, 02:02 PM   #5
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Funny you should mention that, after seeing the 100-300 and having to wait up to 4 weeks to get a Pentax mount 50-500 I am wondering if I made the wrong choice going with Pentax - The vast majority of my photography revolves around wildlife and birds such as albatross, so tracking AF and longer lenses are quite key. I've had my K-30 for about 5 months and love it, but considering swapping to Canon or Nikon before I invest too much in a system which may not be as fully supported in the long lens department in the future.
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