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09-25-2009, 01:44 AM   #1
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Do Any TC's Work With Pentax SDM Lenses?

As the title says.

I'm getting a DA50-135 and just wondering if there is a TC that will allow full use of SDM?

09-25-2009, 01:49 AM   #2
axl
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some of the Kenko 1.5x apparently do, you just need to check if the power zoom contacts are there and not blinded. And i think the story with Kenko 2x MC7 is the same. I think the new ones won't work as the contacts are shorted

BR
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09-25-2009, 01:54 AM   #3
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Kenko 1.5x with powerzoom contacts works, Kenko 2x MC7 with power zoom contacts it doesn´t, only manual focus.
Also tamron 1.4x with power zoom contacts works.
09-25-2009, 03:24 AM   #4
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QuoteOriginally posted by netuser Quote
Kenko 1.5x with powerzoom contacts works, Kenko 2x MC7 with power zoom contacts it doesn´t, only manual focus.
Also tamron 1.4x with power zoom contacts works.
Yes, my Kenko 1.5 TC works fine, BUT! the camera does not understand that there is a TC between the lens and camera. So, all information, like: focal length (important voor the SR algoritm), diafragma etc. are not altered to the real values.

- Bert

09-25-2009, 03:29 AM   #5
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How much do they degrade IQ though?
09-25-2009, 05:25 AM   #6
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QuoteOriginally posted by C.W Tsorotes Quote
How much do they degrade IQ though?
Almost none with Tamron 1.4x
09-25-2009, 03:34 PM   #7
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QuoteOriginally posted by C.W Tsorotes Quote
As the title says.

I'm getting a DA50-135 and just wondering if there is a TC that will allow full use of SDM?

I have the Tamron 1.4xPz AF MC4.

I does work with SDM lenses in that sooner or later it will give focus confirm and take a picture.

As to image quality, I'd have to differ with Netuser. The 50-135 is one of the best lenses Pentax make and it's a bit like buying a Ferrari and putting Kumho economy tyres on it.
09-25-2009, 05:11 PM   #8
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QuoteOriginally posted by netuser Quote
Also tamron 1.4x with power zoom contacts works.
Did you actually try it yourself?

My Tamron 1.4X TC does not work with my DA* 50-135mm. The lens will hunt back and forth for a few seconds on half-press of the shutter release. Then if I remove my finger and then half-press again, it will focus.

I wouldn't call that "working."

My 1.7X Pentax AFA sure works, but it works with anything

09-26-2009, 12:49 PM   #9
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QuoteOriginally posted by SOldBear Quote

My Tamron 1.4X TC does not work with my DA* 50-135mm. The lens will hunt back and forth for a few seconds on half-press of the shutter release. Then if I remove my finger and then half-press again, it will focus.

I wouldn't call that "working."

My 1.7X Pentax AFA sure works, but it works with anything
Hi SOldBear,

My experience exactly matches yours . . . with both TCs. I unfortunately don't think that any definitive statement can be made about which TC will work with SDM -- except for the 1.7x AFA.

Scott
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