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03-18-2016, 09:35 AM   #1
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67 lenses on 645z

Greetings. I am an astrophotographer and a new member of this site.

Has anyone tried putting a Pentax 67 lens on a 645z? Is the image sharp under 645z's resolution?

I recently purchased a 645z with its 35mm and 55mm lens. I am exploring options to increase the array of lenses. I have a few 67 lens (ED300/F4, 165/2.8, and 90/2.8), as I was a Pentax 67 user 10 years ago. So I am thinking if it is a good idea to do so. Of course I should just try it and see if I like the results, but I would also like to hear about other people's experience. (The fact is, astrophotography requires good weather and a moonless night. So it is not as easy as "just try it.")

My general impression of 67 lenses on modern DSLRs is, very bad. I had once put a 67 35mm fisheye on a Canon 5D2. The image quality is horrible. Comparing to any 35mm lens I have, the image just looks as if the lens is defocused. (My Mamiya 67 35mm fisheye does much better on a DSLR.) I had also tried putting the ED300/F4 on a Nikon D800. The image is not as terrifying as the fisheye image, but there is still noticeable aberration. Judging by the shape of stars, I suspect that the lens elements of my 300/F4 are not properly aligned. The misalignment could be caused by the more than 10 years of usage of this lens. Or this could be simply a manufacturing issue, since film does not require very high image quality comparing to modern DSLRs.

So in short, my experience on the 67 fisheye and ED300/F4 was not that good. I am not going to put these two lenses on my 645z. I am wondering whether I should try the 165mm and 90mm, or I should just forget about it. How do you think? Please let me know your experience if you had used 67 lenses on a 645z or 645D.

Cheers,
Wei-Hao

03-18-2016, 09:49 AM   #2
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I've never tried any of these but have had good experience with the 67 55-100. Mike Oria (MikeSF) uses the 67 300mm f4 with terrific results, but I haven't seen astrophotography from him. You might PM him.
03-18-2016, 10:03 AM   #3
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not sure why you have bad experience with 67 lens on DSLR. Have read good reviews on 67 lens performance on digital 645.
as 645 uses only the center portion of 67 lens (135 DSLR even more so), it should be very good.

Do a search online and sure you will find some examples.
03-18-2016, 10:17 AM   #4
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found this one:
https://travel67.wordpress.com/2012/03/07/pentax-645-fa-150mm-f2-8-v-pentax-67-smcp-1652-8/

so it looks like the 165mm is a no go.

03-18-2016, 10:31 AM   #5
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I have a 67 300/4 that I use with my 645D sometimes and it's been pretty good. I haven't done any in-depth testing but images are generally sharp enough as long as I nail the focus.
CA is evident in high contrast areas but it seems to clean up well in Lightroom so I don't worry about it. It's not as sharp as my newer 645 lenses but when I need a 300 it does the trick for me.
03-18-2016, 10:34 AM   #6
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The 35mm fisheye is not one of the best 6x7 lenses. In fact it is the only one I have used that is soft in the corners. Add to that the problem digital sensors have with oblique rays and I can understand the problem you had with the 35, A sharp lens on the 6x7 does not necessarily translate to a sharp lens on the Z.
03-18-2016, 10:52 AM   #7
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QuoteOriginally posted by whwang Quote
My general impression of 67 lenses on modern DSLRs is, very bad. I had once put a 67 35mm fisheye on a Canon 5D2.
Can a lens designed for a 60mm x 70mm frame be expected give high resolution on a 24mm x 36mm frame? Given that 60mm x 70mm negatives did not have to be enlarged as much when printed as with 24mm x 36mm negatives printed to the same print size, medium-format lenses did not need to be as high resolution as lenses made for 24x36mm.
03-18-2016, 11:03 AM   #8
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I use the 67 M* 300/4 and the 67 SMC 105/2.4 on the Z and they both perform great. I don't use that camera for astro though, so i cannot comment on how they work for your purposes.

03-18-2016, 11:12 AM - 1 Like   #9
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QuoteOriginally posted by pete-tarmigan Quote
medium-format lenses did not need to be as high resolution as lenses made for 24x36mm.
But, to takes advantage of the larger frame, it sure would help. In fact several 67 lenses do have 35mm format sharpness. A few 4x5 lenses do as well; a Rodenstock APO Sironar-S 150mm comes to mind. Also, the frame size of the 6x7 is 55 X 70mm.

Last edited by desertscape; 03-18-2016 at 04:33 PM.
03-18-2016, 12:39 PM   #10
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I'm getting wonderful results on my 645Z with Pentax 67 55mm, 105mm, and 200mm lenses. Especially my copy of the 55 - it is stunning. My most common print size is 40x30.

Cheers,
Ross

---------- Post added 03-18-16 at 04:13 PM ----------

QuoteOriginally posted by pete-tarmigan Quote
Can a lens designed for a 60mm x 70mm frame be expected give high resolution on a 24mm x 36mm frame? Given that 60mm x 70mm negatives did not have to be enlarged as much when printed as with 24mm x 36mm negatives printed to the same print size, medium-format lenses did not need to be as high resolution as lenses made for 24x36mm.
This is a common misconception that has been proven false by various tests. The best medium format lenses when used on 35mm DSLRs perform as good as and in some cases better than most 35mm lenses. Leping Zha is a forum member here and elsewhere (and an outstanding landscape photographer) who has a great post detailing his own tests where his Pentax 67 lenses outperformed his Canon glass:

Resolution Chart Test Image 100%: Pentax 67 Zoom Lens on the 5DII 5um Pitch Sensor: Nikon FX SLR (DF, D1-D5, D600-D800) Talk Forum: Digital Photography Review

Cheers,
Ross

Last edited by SeattleDucks; 03-18-2016 at 01:14 PM.
03-18-2016, 10:01 PM   #11
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I have been testing the P67 and some 645 lenses on the Sony 7rm2 via adaptors, and once stopped down a litle bit, they perform stellar even on 42mp FF sensors frankenmonster - Arufu Photography & Studio Rental
03-19-2016, 12:55 AM   #12
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QuoteOriginally posted by SeattleDucks Quote

This is a common misconception that has been proven false by various tests. The best medium format lenses when used on 35mm DSLRs perform as good as and in some cases better than most 35mm lenses.
Cheers,
Ross
This is actually consistent with what I found. When I compared lenses from the film era, nearly all the Mamiya 645 and 67 lenses I put on my D800 outperform my Nikon lenses of similar focal lengths. On the other hand, these old medium format lenses can't compete with new lenses designed for DSLR, such as the Sigma Art lenses. Overall, my experience on Mamiya lenses has been quite good, but not on the few Pentax 67 lenses that I had tried.

Based on what people said here, I think I should give my Pentax 67 90mm a serious try.

Cheers,
Wei-Hao
03-19-2016, 11:56 PM   #13
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The 67 lenses are great fun to shoot with , but after using the DFA glass I have to admit that most of the 67 glass (except the 55-100) sits around as "back up" in case the DFA glass needs repair........
04-03-2016, 04:46 PM   #14
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QuoteOriginally posted by 672 Quote
I have to admit that most of the 67 glass (except the 55-100) sits around as "back up"
Pentax had made great strides in lens performance between 1969 and 2001 with their 67 glass. The most recent designs were really nice. The 55-100, 90-180 and 75AL were all designed in this latest period between 1998 and 2001.
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