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01-22-2014, 07:45 PM   #1
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Older Sigma lenses

I am thinking about purchasing a Pentax K-r camera. I have two older Sigma lenses that I used with my film Pentax K1000. I have read that these could be problematic as far as mounting to the K-r. Has anyone experienced difficulties with the Sigma lenses? Any suggestions as to what to look for before I ruin a new camera body?

01-22-2014, 07:53 PM   #2
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QuoteOriginally posted by kgalvinmhe Quote
I am thinking about purchasing a Pentax K-r camera. I have two older Sigma lenses that I used with my film Pentax K1000. I have read that these could be problematic as far as mounting to the K-r. Has anyone experienced difficulties with the Sigma lenses? Any suggestions as to what to look for before I ruin a new camera body?
If they worked with your k1000 they'll fit on a DSLR without any issues. You will have to focus and meter manually, however:
https://www.pentaxforums.com/forums/54-pentax-lens-articles/110657-how-use-me...k-x-k-7-a.html

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01-23-2014, 08:39 AM   #3
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Older Sigma Lenses

Thanks Adam for the quick reply. I am actually looking forward to going back to a manual mode.
01-23-2014, 10:20 AM   #4
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There are possibly one or two catches.

The flange that protects the aperture lever might be too big preventing you from mounting it completely. Some surgery is required in that case.
I'm not sure about this second one, but if Sigma ever made lenses with a Ricoh pin and you have those, they can get stuck on the camera. Do some research.

You can check Pentax Lenses by Sigma, Tamron, Zeiss, and more - Reviews and Specification Database - Pentax Lens Review Database if anything of the above has been mentioned for the lenses that you currently own.

01-25-2014, 05:39 PM   #5
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QuoteOriginally posted by sterretje Quote
There are possibly one or two catches.

The flange that protects the aperture lever might be too big preventing you from mounting it completely. Some surgery is required in that case.
I'm not sure about this second one, but if Sigma ever made lenses with a Ricoh pin and you have those, they can get stuck on the camera. Do some research.

You can check Pentax Lenses by Sigma, Tamron, Zeiss, and more - Reviews and Specification Database - Pentax Lens Review Database if anything of the above has been mentioned for the lenses that you currently own.
Thanks for the heads up. I read elsewhere that some of the Sigma lenses have gotten stuck and had to be taken to a camera shop to remove. I definitely do not want to ruin a brand new camera.

Thanks again sterrejte and I will do my homework.
01-28-2014, 09:11 AM   #6
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Sigma lenses

I have a Sigma 28-200 zoom which I used for some 20 years with my K1000. My decision to buy a Kr was a lot to do with having this lens.


It fits perfectly and imagine my surprise and delight when I found it was auto focus which it had never been with the K1000, and works with the auto pict setting.


I have had very good results and use it most of the time.


I have two other manual lens which I use but they are not as convenient.
01-29-2014, 04:57 AM   #7
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Thanks for the information George. I have two Sigma lenses, one is a 70-200 zoom and a 28-70 zoom which I recently purchased new but from old inventory off EBay.. Those are the two lenses I want to use but also the Pentax 50 mm. Do you find with the APS size sensor that the normal lense (50 mm) is more like a 75mm? I read somewhere the crop factor is 1.5 when used with old film lenses. Would the same be true of the two Sigma lenses? What lenses did you have trouble using with the K-r?
Look forward to your response.
Thanks!
01-29-2014, 10:25 AM   #8
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QuoteOriginally posted by kgalvinmhe Quote
Do you find with the APS size sensor that the normal lense (50 mm) is more like a 75mm?
The field of view of the 50mm on the K-r will be about the same as the field of view of the 70-200 @70mm on your K1000. Further the crop factor does not have anything to do with old or new lenses; if you put an old 50mm or a new 50mm on the K-r, they will give exactly the same results (DOF, field of view).

If you often use your 28-70 at the 28mm end on the K1000, you will probably miss the wider view when you use it on the K-r; time will tell. A 18-55 or 17-50 on the K-r will give roughly the same field of view of the 28-70 on the K1000.

01-29-2014, 12:16 PM   #9
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That is what I undserstood but wasn't sure. Thanks for the confirmation.
01-30-2014, 08:35 AM   #10
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I have noticed that the "normal" focal length is 35mm rather than 50mm. I have the kit lens 18-55, a Carl Zeis Jenna 35mm flektogon (screw thread) and the Sigma 28-200. I am not sure if the kit lens quoted focal length takes into account the APS sensor, I suspect it doesn't as the 18 is not as wide angle as I would expect. The Flektogon is a really good lens but the auto does not work with the adaptor. However the close focus of 10cm is very useful and I get good results on manual. I had a problem with the aperture blades not closing and the members helped me clean and repair the lens, they are very helpful.
01-30-2014, 01:09 PM   #11
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QuoteOriginally posted by Chicken George Quote
I am not sure if the kit lens quoted focal length takes into account the APS sensor, I suspect it doesn't as the 18 is not as wide angle as I would expect.
Focal length is a physical property of a lens; it does not matter on what type of camera it is mounted, it stays the same focal length.
01-31-2014, 01:42 AM   #12
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I understand that the focal length is a physical property, I meant the perceived results from a given lens from the film camera days where 50-55mm was considered the "normal" view compared to the human eye. Sorry I did not explain myself very well. Am I correct in thinking that the kit lens 18-55mm gives similar field of view with the smaller sensor that a 28-75mm would give on a full size one?
01-31-2014, 04:49 AM   #13
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Yep, you got the point.
01-31-2014, 04:53 AM   #14
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The 28-70 will work fine but you will be left wanting something wider.
02-03-2014, 10:26 PM   #15
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QuoteOriginally posted by Lowell Goudge Quote
The 28-70 will work fine but you will be left wanting something wider.
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