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03-14-2013, 02:58 AM   #1
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Converters on Sigma 70-200 HSM II?

I'm seeking comments from anyone who has found a good quality teleconverter to marry to the Sigma 70-200mm F2.8 EX DG APO Macro HSM II. Thanks in advance.

03-14-2013, 03:59 AM   #2
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I use the Pentax 1.7x AFA - it is the only one which will work for the Pentax mount.
03-14-2013, 05:11 AM   #3
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QuoteOriginally posted by bhairavp Quote
it is the only one which will work for the Pentax mount

Not exactly. Sigma also currently markets two teleconverters that will work with most any Pentax digital slr
03-14-2013, 07:16 AM   #4
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Not sure that works with Pentax - Sigma has not launched any HSM-compatible TCs for the K Mount

03-14-2013, 11:38 PM   #5
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QuoteOriginally posted by bhairavp Quote
I use the Pentax 1.7x AFA - it is the only one which will work for the Pentax mount.
ditto, but it doesn't report the correct F ratio but still exposes OK.
bb2
03-15-2013, 02:29 AM   #6
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^Pins 1 and 4 on the lens side of the adapter should be taped, you'll get the correct F number in EXIF.
03-15-2013, 02:52 AM   #7
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If I could ask some clarifying questions of the Pentax 1.7x: -

- Is the lens AF speed and accuracy maintained?
- How much image sharpness is lost through teleconversion?

I'm not after explicit details, just a general opinion from first hand experience.

Thanks in advance.
03-15-2013, 03:51 AM   #8
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^You have to manually prefocus to the general vicinity of the subject, and then the AFA takes over to lock on. Generally decently accurate.
I've only taken a few shots with my Sigma so far, but it seems to be quite sharp, even wide open. It doesn't make sense using it with slower lenses, as the 1.7x reduction in f-stop makes for difficult AF locks.

03-15-2013, 04:13 AM   #9
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I have had personal experience with the Tamron 1.4x Pz-AF, which is SDM compatible, with the Sigma 70-200 II and it was unable to fix focus at focal lengths from about 160-200mm, even in full sunlight. So the focal range where you would really want it to perform, it failed to do so with this TC. I gave up with the Sigma and went with the screwdriven Tamron 70-200 which works perfectly with the aforementioned TC.
03-15-2013, 04:18 AM   #10
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QuoteOriginally posted by bhairavp Quote
^Pins 1 and 4 on the lens side of the adapter should be taped, you'll get the correct F number in EXIF.
Thanks for that. Does report correct F ratio on rear LCD, although not on the top window. Dark here now so need to do testing tomorrow in bright light.
I think the combo of lens plus TC needs to be stopped down a couple of stops to get rid of some flare. Nett result is sharp so TC is useful. AF is usually very fast with the Pentax 1.7 AF TC.
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03-15-2013, 04:39 AM   #11
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bhairavp - that's what I needed to know. Thanks.
03-15-2013, 04:57 AM   #12
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QuoteOriginally posted by beachboy2 Quote
Thanks for that. Does report correct F ratio on rear LCD, although not on the top window. Dark here now so need to do testing tomorrow in bright light.
I think the combo of lens plus TC needs to be stopped down a couple of stops to get rid of some flare. Nett result is sharp so TC is useful. AF is usually very fast with the Pentax 1.7 AF TC.
bb2
Use the hood.. it makes a difference. Very little flare here.
Ash- exactly, the AFA 1.7x is the only "TC" that will work correctly with the 70-200 HSM II on Pentax.

Last edited by bhairavp; 03-15-2013 at 07:33 PM.
03-15-2013, 08:13 PM   #13
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QuoteOriginally posted by beachboy2 Quote
Thanks for that. Does report correct F ratio on rear LCD, although not on the top window. Dark here now so need to do testing tomorrow in bright light.
I think the combo of lens plus TC needs to be stopped down a couple of stops to get rid of some flare. Nett result is sharp so TC is useful. AF is usually very fast with the Pentax 1.7 AF TC.
bb2
Whoops! So covering the pins gets correct aperture recorded but AF is lost. So think I'll stick to incorrect aperture and super fast AF.
cheers
bb2
06-10-2013, 07:41 AM   #14
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QuoteOriginally posted by beachboy2 Quote
Whoops! So covering the pins gets correct aperture recorded but AF is lost. So think I'll stick to incorrect aperture and super fast AF.
cheers
bb2
Has anyone posted sample photos or a YouTube video of the 70-200 hsm II functioning with a teleconverter? If you know of any, could you please post a link? If not, and anyone has this combo, a sample photo or video would be much appreciated!

Thanks
Mikal
06-10-2013, 10:38 AM   #15
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I shot these last friday, first time with my Pentax AF1.7 - Sigma 70-200 HSM combo. it worked fine for me. Sharp enough and easy to focus. I have not tried taping the contacts to get the proper f-stop values yet.





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