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05-10-2009, 07:33 AM   #1
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Sigma teleconverter compatibility

I was looking at the Sigma compatibility list for it's teleconverters at Tele Converter matching list - SIGMA CORPORATION. The list for cameras such as Nikon and Canon are clear enough, but under Pentax several of the lenses simply state X rather than AF or MF. I can't find any explenation on what this means. Anyone have any idea?

05-10-2009, 09:10 AM   #2
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The crosses are for the new HSM Sigma lenses.
The teleconverters will not work with them, Sigma totally messed that up.
05-10-2009, 10:25 AM   #3
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Mike has the right answer. the sigma 1.4x and 2x TCs do not support HSM (they lack the power contacts of the KAF2 mount, and sigma does not include a screw drive on the HSM lenses for back compatability.

Note also that the sigma 1.4x and 2x TCs only ever worked with a limited range of sigma lenses because the front element of the TC protrudes into the lens a little. They were specifically designed for the long fast tele zooms and primes and not as a general TC where you would want to double the focal length of a shorter lens because you were in a pinch and needed extra length
05-10-2009, 11:01 AM   #4
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Can't believe they broke compatibility with their own lenses. Here's hoping they'll develop some new TC's which work with HSM.

06-29-2017, 01:52 AM   #5
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HI, does anybody know if this lens Sigma 70-200mm F2.8 APO EX Lens Reviews - Sigma Lenses - Pentax Lens Review Database will be compatible with this teleconverter SIGMA APO 2x EX DG Teleconverter Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database , if AF will works normal with K1 ?
06-29-2017, 09:48 PM   #6
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Does anybody know, please? I need to make decision . thanks
06-30-2017, 02:36 PM   #7
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QuoteOriginally posted by 88lukas88 Quote
Does anybody know, please? I need to make decision . thanks
I have the lens and teleconverter, but not a K1. However, auto focus does work on my K3.
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06-30-2017, 05:42 PM   #8
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QuoteOriginally posted by dtrego Quote
I have the lens and teleconverter, but not a K1. However, auto focus does work on my K3.
Thanks, do you like the converter on your K3 ? Could I see somewhere your photos with the lens and teleconverter ? How is the sharpness? Thanks again

07-01-2017, 08:02 AM   #9
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Have to admit that I haven't actually shot with this combo yet. The TC is a recent addition. I just put it together to see if it would fit and focus in response to your post. I'll see if I can take a few shots today.
07-01-2017, 02:40 PM   #10
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QuoteOriginally posted by 88lukas88 Quote
I did have the TC 2X, and used it with the 70-200 2.8 EX (original version) - but, eventually, sold it on because it slowed the AF down and made it more uncertain (What, Pentax AF is "uncertain"?) , especially, later, with the 100-300 F4. OTOH, the 1.4xTC generally works quite well with both lenses, and so I have kept that one.
07-02-2017, 12:50 PM   #11
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After taking a few shots, I agree with jeallen01 above. It worked, but seemed to take longer to actually lock focus. It didn't rack all the way in/out, but there were a lot more fine focus adjustments before the focus confirmation indicator lit up. Usable in a pinch, though. On my setup, I found that the addition of the TC made it necessary to tweak the fine focus adjustment via the camera's menu. My lens takes a +2 by itself, but that was quite soft with the converter. Changing it to +6 improved it quite a bit. Here's one shot, handheld, at 200mm/f2.8 on the lens (so really 400mm/f5.6). PM me for the raw file if you want to pixel peep.
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07-02-2017, 05:05 PM   #12
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Thank you for your report jeallen01 and yeah I would prefer more 1.4 but I can't find it. dtrego, thanks you too and I sent you PM. Thanks again.

07-03-2017, 01:40 AM   #13
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QuoteOriginally posted by 88lukas88 Quote
Thank you for your report jeallen01 and yeah I would prefer more 1.4 but I can't find it. dtrego, thanks you too and I sent you PM. Thanks again.
Good luck in finding a 1.4X, but it will take time and probably cost you more than the 2.0X because it is more popular than that one.

OTOH, you could try to find a general-use 1.4X/1.5X TC - read the reviews of the various versions here https://www.pentaxforums.com/userreviews/pentax-off-brand-teleconverters-c90.html
and in quite a number of converter-specific threads.

However it must be one with the "Pz" contact and marking as only those are compatible with the AF system - otherwise you will have only manual focusing.

Last edited by jeallen01; 07-03-2017 at 05:38 AM.
07-03-2017, 05:09 AM   #14
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QuoteOriginally posted by 88lukas88 Quote
If you are discussing the sigma lens with no "DG" classification, I.e. From the film era, yes it works with the sigma 1.4 and 2x teleconverters. I have had this lens since 2003 and use it with both TCs

I have even once stacked the two TCs but the 1.4 must go behind the 2x in this case. AF is slow and a little dodgy unless in bright sunlight with the two TCs stacked.

Optically this lens is one of the best sigma 70-200 lenses as it is sharp at especially 200mm. Later macro versions were soft at maximum focal length
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