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03-02-2014, 05:04 PM   #1
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Q: Pentax 1.7X AFTC & PK+MM adapter

Well, I'm sure some of you must've seen the PK mount converter by the Adaptist known as the "Multi Mount". While I am interested in converting one of my bodies to be able to use Nikon and Olympus glass, what I'd really like to try is converting a Pentax 1.7x AFTC. I believe that this would allow autofocus with long Nikon glass like the 400mm 2.8, and 3.5. I am wondering if anyone else has thought of this or even tried it yet?

03-02-2014, 05:12 PM   #2
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You won't get autofocus with non K mount lens with a Pentax camera, no matter what adapter you use. AF technology is too different between brands to be converted. With the Multi-mount, you don't even get aperture control on "adapted" lenses.
03-02-2014, 05:24 PM   #3
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I don't think the multi mount supports any sort of af.

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03-02-2014, 05:34 PM   #4
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But with the AFA autofocus is handled there not in the lens. So what is out in front should not matter?

03-02-2014, 05:47 PM   #5
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QuoteOriginally posted by jatrax Quote
But with the AFA autofocus is handled there not in the lens. So what is out in front should not matter?
Yeah you're right, I had the multi mount in the wrong spot in my head...
03-02-2014, 06:23 PM   #6
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I've heard it works with adapted M42 lenses, so I don't see any reason it wouldn't work if you could get the mount to fit.
03-02-2014, 06:26 PM   #7
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The TC AF is limited, you would have to manual focus somewhat close first to get a lock, but in essence it should work
03-03-2014, 12:52 AM   #8
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QuoteOriginally posted by jezza323 Quote
The TC AF is limited, you would have to manual focus somewhat close first to get a lock, but in essence it should work
Yeah, I already know about the limited AF range of the TC itself. I've already been using one with a Sigma 300mm f2.8 so I'm kind of used to "getting it close" manually, then letting the AFTC handle the final locking up. I find that this works pretty well for surfing and most of the birding I've been doing in Hawaii. I'm just wondering if I could expand things to other brands of glass by converting the mount on the TC rather than the camera body... One of the members on the Pentax forum at dpreview (brandrx) has a setup where he "sort of" mounts a Nikon 400mm f2.8 to a Pentax 1.7x AFTC and uses a jig setup to ensure that the two stay locked together. The PK+MM would help eliminate the jig, and the AFTC would allow "limited" autofocus, correct?

03-03-2014, 05:11 AM   #9
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QuoteOriginally posted by HawaiianOnline Quote
Yeah, I already know about the limited AF range of the TC itself. I've already been using one with a Sigma 300mm f2.8 so I'm kind of used to "getting it close" manually, then letting the AFTC handle the final locking up. I find that this works pretty well for surfing and most of the birding I've been doing in Hawaii. I'm just wondering if I could expand things to other brands of glass by converting the mount on the TC rather than the camera body... One of the members on the Pentax forum at dpreview (brandrx) has a setup where he "sort of" mounts a Nikon 400mm f2.8 to a Pentax 1.7x AFTC and uses a jig setup to ensure that the two stay locked together. The PK+MM would help eliminate the jig, and the AFTC would allow "limited" autofocus, correct?
This has often crossed my mind as well. But the cost of the TC might be a little prohibitive to hack up. There are, however infinity adjusted Nikon,canon and Minolta to pentax converters, and each of these is really a TC, so if you did use a much better optical solution it would likely work, with the pentax converter. The biggest issue is you would have manual stop down for the aperture,

The Nikon thing is not really an adaptor, the Nikon mount is close enough to partially engage. The rigging is external to ensure the cameras does not fall off
03-03-2014, 12:26 PM   #10
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It is a great idea! It should work in theory, as long as the connectors are shortened (have metal contacted). There are some thread discussing how to use M42 lenses on 1.7x AFTC. If the PK+MM adapter can be installed, I don't see any reason the AF will not work.
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