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12-27-2012, 07:57 AM   #1
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645D with old manual lenses

Hello to all..

I am in process of thinking to expand my arsenal with 645D
At the moment i have P6 lenses such as Pentacon 135mm f2.8, and 200mm f4, and few others.. they are all m42 Mount..

Since i do not know the Pentax system well.. and would like to get as much info before purchasing.. my question is this..

Will I be able to use those lenses and any other manual focus lens on the 645D system?
Is there any adapter that I can use to pair up with the lens?
What are your thoughts and experiences on manual focusing wide open and stepped down?

Best Wishes from Macedonia,

12-27-2012, 08:18 AM   #2
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I can't speak as to whether those lenses will work or not ( I don't think they will because I believe their image circle is too small and they may not focus at infinity), but I can speak for manual focus lenses on the 645D. I have the 645 35mm A lens, and it's a breeze to focus, as most of the time I'm shooting either at or very near infinity, so you just crank it until it stops. I'm shooting landscapes on a tripod (which usually aren't moving), so that makes manual focus easy. The 645 25mm D FA is a bit harder to focus, as it's a touch darker in the viewfinder, but it also has AF, so no big deal. My 200mm lens is hard to focus, since it's a telephoto and infinity focus isn't usually accurate if you crank all the it's touchy. But, I have 20/20 vision, so it's still doable (and I can check focus after I shoot with the viewfinder by zooming into about 8X). I believe both the 45-85 and 80-160 zooms hold focus as you zoom them, so that's nice. I have the AF versions of both, as they weren't much more costly than the M versions.

Shooting landscapes offers much more time to get the focus right. If I had moving subjects, then the AF versions would be much better.

When I shot some bison in the Grand Tetons with the 300mm A lens, I was usually off on my focus (plus had my own camera shake issues), so in that case it would have been better to have a AF lens...I just didn't want to pay twice as much for a lens I won't use very often. I'm thinking about getting a K5 to help alleviate the shake part of the issue for when I shoot future wildlife.

The 645D is not the best camera for sports or wildlife to begin with, so if you see yourself shooting moving objects with it, I'd opt for AF lenses (or get a K5 with 645 adapter). Of course, I'm not very practiced with my 'snap' manual focusing, so others probably get better results.

If you have bad vision, then I'd say it's going to be much more difficult to find focus manually, so take that into consideration as well. has had some really good sales on used 645 glass of late...I'd take a look there, as well at the marketplace in this forum. Also, adorama usually has a few used 645 pentax lenses at decent prices in stock.

Best of luck!
12-27-2012, 08:37 AM   #3

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Pentacon 6 lenses have a large enough image circle since they were made for a 6x6 film camera but the lenses you are listing sound like 35mm lenses.
12-27-2012, 11:27 AM   #4
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They are medium format lenses both of them have image circle that is for 6x6

12-27-2012, 11:52 AM   #5
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Well, here is a bit of information....
12-28-2012, 02:53 PM   #6

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QuoteOriginally posted by martinMK Quote
They are medium format lenses both of them have image circle that is for 6x6
Interesting. I don't know a lot about Pentecon Six and its derivatives but I thought they all had a bayonet mount and not a M42 screw mount. Tell us more about your camera model.

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