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08-05-2010, 05:00 PM   #1
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more adaptor questions...minolta to pentax

I have found what I think will work on ebay...........but wanted to confirm that I am correct and that it is worth the effort and $.
I have a lovely Vivitar Auto macro 55mm 1:2.8 1 to 1 macro in the minolta mount. It has M/SR on it but I believe it is an MD mount. The serial number starts with 28 so its a Komine make?

Minolta MD MC Lens to Pentax Adapter Focus Infinity - eBay (item 250643030383 end time Aug-30-10 05:45:09 PDT)

will I get good IQ? or am I better off selling it on...........I dont think I am game to try a coversion and wreck a beautiful lens
cheers
Jan

08-05-2010, 05:30 PM   #2
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it will work but...

I have similar adaptors for Nikon AI and Canon FD lenses.

they are in fact a small teleconverter, with magnification used to in conjunction with the tube length to retain infinity focus

I don't know how much magnification you will have, but the nikon one is 1.25x and the canon one is 1.45x.

this one, I suspect may also be in the 1.25x range, but you won't know until you test it,

check the following thread for a discussion on the adaptors.

https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/25368-using-ca...ntax-body.html

https://www.pentaxforums.com/forums/pentax-camera-field-accessories/96884-ada...addiction.html

my conclusion is they are ok for macro and tele applications but not for wide angle.

for you it may be worthwhile
08-05-2010, 05:32 PM   #3
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There are no Minolta converters available, at least one that offers infinity focus. The one you linked to will offer infinity focus but the corrective element in there will degrade the image quality and probably convert it to a 75mm f4.0 or 5.6 probably. It's a trade off. I personally would never use an adapter with corrective glass in there but other members have used it and reported no problems.

I would rather do the mount conversion, it only takes a few hours.
08-05-2010, 05:35 PM   #4
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Read through the new dimensions for LBA thread.

https://www.pentaxforums.com/forums/pentax-camera-field-accessories/96884-ada...addiction.html

The MD adapter just recently became available so I don't know much about it.

08-06-2010, 05:11 PM   #5
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Many thanks people,
after much tooing and froing with hubby we are gonna try the conversion.........I will need to order the flanged adapter ( not gonna donate my original pentax one!).
and his suggestion was to get machining done professionally........there is a local guy that does it with some computer gizzo so it should be exact.......
Are there many pifalls ?
and I will try to document it........
cheers
Jan
08-06-2010, 05:59 PM   #6
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I converted a Kirin in minolta mount to K mount with a flanged adaptor

There is a little machining necessary to remove some material on the aperture ring that overhangs the mount

Infinity focus needs some attention to get spacings right but it is possible on some lenses to adjust infinity focus. I posted the process for kirin lenses
08-06-2010, 07:28 PM   #7
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could you please point me in the direction of your post? I searched but cant find it!

ok there seems to be an issue with the direction the aperture lever goes?

Last edited by janstew; 08-06-2010 at 10:44 PM.
08-06-2010, 10:49 PM   #8
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and onother question...........with the adaptor? what would happen or is it possible to take the glass out?

08-07-2010, 04:56 AM   #9
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There are issues converting mounts with respect to aperture activation. Most become manual stop down lenses

With respect to the adaptor and glass removal it becomes an extension tube good for macro work only
08-07-2010, 06:32 AM   #10
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Your best bet is selling on the lens. The Minolta register is shorter for a start plus plus aperture activation mechanisms are likely to be different.
08-07-2010, 01:26 PM   #11
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I am starting to think it would be easier to sell it on as well..........
To covert I would lose the aperture arm ( althought the ring should still work so long as I dont break it ) . There may be too many risks for me. Phooey
cheers
Jan

Last edited by janstew; 08-07-2010 at 01:27 PM. Reason: cause I cant spell at this hour of the morning
08-11-2010, 03:57 PM   #12
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50/2.8 macro lenses for Pentax are not hard to come by. Definitely not worth the effort and compromises involved with a conversion or adapter.
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