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10-11-2010, 01:08 PM   #1
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Tamron 2X Pz-AF BBAR MC7

I am going to get this TC, will it work properly with my K-x and DA lenses.

10-11-2010, 01:11 PM   #2
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Yes, it will autofocus with DA lenses.
10-11-2010, 01:57 PM   #3
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Note that this TC (in fact, all 2X TCs currently available) does not autofocus with SDM lenses.
10-11-2010, 03:32 PM   #4
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QuoteOriginally posted by SOldBear Quote
Note that this TC (in fact, all 2X TCs currently available) does not autofocus with SDM lenses.
I believe this is generally true. However it turns out I was able to get this 2x TC to work with one SDM lens, the DA17-70. I was just fooling around to see if it would work as having a 34-140/8 wouldn't really be very practical But it did in fact AF using the SDM through the TC... needless to say I was very surprised.

10-11-2010, 04:04 PM   #5
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QuoteOriginally posted by dgaies Quote
I believe this is generally true. However it turns out I was able to get this 2x TC to work with one SDM lens, the DA17-70.
I believe the "PZ" in the TC description means it will accommodate Pentax Power Zoom lenses and therefore should auto-focus with SDM lenses. I have a Kenko 1.5x with PZ contacts and it worked with a 50-135. Slow and halting AF, but it did focus.
10-11-2010, 04:22 PM   #6
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QuoteOriginally posted by audiobomber Quote
I believe the "PZ" in the TC description means it will accommodate Pentax Power Zoom lenses and therefore should auto-focus with SDM lenses.
Can't make the Tamron 2X TC to autofocus with any of the DA* lenses I have (60-250, 50-135, 16-50). I don't have the 17-70 and have no reason to doubt dgaies's report.

The Tamron 1.4X TC "kind of" works with DA* lenses. "Kind of" because it hunts a lot when the zoom lens is at the long end for the range (there's no reason to use a TC at the short end).
10-11-2010, 04:24 PM   #7
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QuoteOriginally posted by audiobomber Quote
I believe the "PZ" in the TC description means it will accommodate Pentax Power Zoom lenses and therefore should auto-focus with SDM lenses. I have a Kenko 1.5x with PZ contacts and it worked with a 50-135. Slow and halting AF, but it did focus.
That's true (about the PZ contacts). However, my understanding is that there is more too it than just having the contacts. In the case of the 2x, none of my other SDM lenses would even attempt to AF. It was as if there was no connections at all. That's why I was quite surprised to find that the 17-70 worked. The only difference I can think of is that the 17-70 is SDM only, and the other SDM lenses I tried technically had both SDM and screw-drive.
10-11-2010, 06:43 PM   #8
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QuoteOriginally posted by dgaies Quote
That's true (about the PZ contacts). However, my understanding is that there is more too it than just having the contacts. In the case of the 2x, none of my other SDM lenses would even attempt to AF. It was as if there was no connections at all. That's why I was quite surprised to find that the 17-70 worked. The only difference I can think of is that the 17-70 is SDM only, and the other SDM lenses I tried technically had both SDM and screw-drive.
Good to know. Thanks.

11-15-2010, 01:30 PM   #9
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QuoteOriginally posted by dgaies Quote
I believe this is generally true. However it turns out I was able to get this 2x TC to work with one SDM lens, the DA17-70. I was just fooling around to see if it would work as having a 34-140/8 wouldn't really be very practical But it did in fact AF using the SDM through the TC... needless to say I was very surprised.
I have the same TC and 17-70. It will AF in the shorter focal lengths. Once I zoom in to over 30mm it "hunts."

What are the settings you are using for it to work properly?

I might be buying a Tamron 70-200 2.8. I think that will be a good match for my TC and k20D.

Thanks
11-15-2010, 07:29 PM   #10
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QuoteOriginally posted by bluebronco Quote
I have the same TC and 17-70. It will AF in the shorter focal lengths. Once I zoom in to over 30mm it "hunts."

What are the settings you are using for it to work properly?

I might be buying a Tamron 70-200 2.8. I think that will be a good match for my TC and k20D.

Thanks
Yes, it works until 75% (aprox.) of the lens's zoom capability (with my sigma 100-300mm until 200mm; with my DA 50-200mm until 150mm), funny ehh.
11-15-2010, 07:38 PM   #11
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QuoteOriginally posted by bluebronco Quote
I have the same TC and 17-70. It will AF in the shorter focal lengths. Once I zoom in to over 30mm it "hunts."

What are the settings you are using for it to work properly?

I might be buying a Tamron 70-200 2.8. I think that will be a good match for my TC and k20D.

Thanks
I don't have the 17-70 anymore, and to be honest I don't recall what focal lengths it worked with. I know it was spotty at best with the 17-70.

I actually have a 70-200 coming in this week, so I can let you know how the combo works together. It was actually suppose to be here today, but somehow got sent to Iowa instead of Maryland so it's going to be delayed a couple days (I guess the postman read the first 2 in the zip code as a 5).
11-15-2010, 11:06 PM   #12
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I forgot to mention that the Tamron 2X Pz-AF BBAR MC7 does not autofocus with the Ltd. DA 70mm. Autofocus just hunts back and forth.

I myself don't have direct experience with the DFA Macro 100mm WR, but I heard that it had the same issue.
11-16-2010, 07:16 AM   #13
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QuoteOriginally posted by SOldBear Quote
I forgot to mention that the Tamron 2X Pz-AF BBAR MC7 does not autofocus with the Ltd. DA 70mm. Autofocus just hunts back and forth.

I myself don't have direct experience with the DFA Macro 100mm WR, but I heard that it had the same issue.
I have heard the same about the DA70 (from the person to whom I sold one of my Tamron 2x TC).

Regarding the 100 WR macro, it will AF with the 100 WR but it moves the focus ring in very short, quick bursts and takes a while if you are far from the focus point. If you quick-shift close to the right focus, the AF will lock on pretty well.
11-16-2010, 07:36 AM   #14
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One aspect with TCs and AF would be that these might push the effective minimum aperture beyond AF capability: phase detect AF is based on light entering from the borders of the lens focusing at the same point when the lens is in focus and on different points otherwise. When the aperture gets smaller, the difference when not in focus gets smaller and the AF sensors eventually stop working.

Also the body would assume a wrong aperture and this might throw the AF algortihm out of track, especially this might use different sensors or different weights for their readings: the cross sensors, as I understand them, actually consist of two different sensors at right angles, one 'tuned' for larger apertures (~2.8) and the other for small ones (~5.6).
11-16-2010, 09:42 AM   #15
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I sent an email to Tamron asking if the TC and the 70-200 f2.8. Here is the response I received:

We do not recommend the use of teleconverters with digital lenses/cameras, as you may experience image quality or auto focus issues. For more information, please see this service update: Tamron; Digital Camera Lens (DSLR), Security CCTV Lenses

If you have any other questions, please don't hesitate to contact me!

Regards,

Customer Service
Tamron USA, Inc.
10 Austin Blvd.
Commack, NY 11725
631-858-8400
____________________

I might be selling my TC and try to find a lens/TC that is compatible. I like that 70-200mm range.

Any suggestions? Pentax? Sigma?
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