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07-20-2015, 05:45 AM - 8 Likes   #1
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Block diagrams of every 645 A series lens

(I didn't know if I should post this in SLR lens discussion or not)

I have been searching high and low for these, and I was beginning to think that they didn't exist outside of a filing cabinet in a Tokyo patent office. But somehow I stumbled upon them, and here they are without further ado!

SMC Pentax 645 A Teleconverter 2x

SMC Pentax 645 A Teleconverter 1.4x

SMC Pentax 645 A 35 f/3.5

SMC Pentax 645 A 45-85 f/4.5

SMC Pentax 645 A 45 f/2.8

SMC Pentax 645 A 55 f/2.8

SMC Pentax 645 A 75 f/2.8

SMC Pentax 645 A 75 f/2.8 Leaf Shutter

SMC Pentax 645 A 80-160 f/4.5

SMC Pentax 645 A 120 f/4 Macro

SMC Pentax 645 A 135 f/4 Leaf Shutter

SMC Pentax 645 A 150 f/3.5

SMC Pentax 645 A 200 f/4 [IF]

SMC Pentax 645 A* 300mm f/4 ED [IF]

SMC Pentax 645 A* 600mm f/5.6 ED [IF]

Last edited by Fat Albert; 07-20-2015 at 09:21 AM.
07-20-2015, 06:03 AM   #2
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Thanks for posting. I have most of these and have never seen the diagrams either.
07-20-2015, 06:08 AM   #3
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Good info.
Is that available for the old 6x7 Takumars?
The 75mm lenses look like classical double gauss.
07-20-2015, 09:19 AM - 1 Like   #4
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I'm going to try the 67 lenses next.

You all have no idea what I went through to find these. Hours and hours of searching every possible word combination I could think of. Searching links. Searching images. If I see one more picture of a stock 645 lens, I'm going to scream. After a while, I began to wonder whether these actually existed on the world wide web.

Interestingly enough, Ken Rockwell, of all people, has some of the most comprehensive Pentax 645 lens info out of anybody out there--but only for the lenses he reviewed. I must say, his approach to Pentax is almost schizophrenic. He'll knock the K-3 packaging, and then rave about the focusing smoothness of the 645 lenses. Like, full-on gush. Very interesting.

07-20-2015, 09:58 AM - 2 Likes   #5
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Thanks for posting the 645's, the 6x7 are as follows:

Pentax 6x7 Wide

Pentax 6x7 Normal/Short Telephoto

Pentax 6x7 Telephoto

Pentax 6x7 Special

07-20-2015, 10:52 AM - 2 Likes   #6

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Make this sticky!
07-20-2015, 12:37 PM - 1 Like   #7

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I had given up looking for the 120 macro cross section. Glad to see it here. It is a most bizarre design and one that I have never seen before. The 150 and 200 are very similar to the older 200 Takumar for the 6x7 (triplet variants). Surprised that they were not the newer Ernostar design of the newer 200mm for the 67. The 45-85 zoom looks almost identical to the 55-100 for the 67.

What is curious about the designs for the 645 is that they are not just a scaled down versions of the 67 designs. You can see communication between design teams on some of the lenses but overall they are quite different.

Great information-- Agree this should be a sticky for reference.

Last edited by desertscape; 07-21-2015 at 12:10 PM.
07-23-2015, 10:18 PM   #8
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These are all very interesting to look at, I have always been curious as to why these cross sections are useful to someone? Or is it just a interesting subject for you?

07-24-2015, 01:07 PM   #9

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Thomas- I can fully understand what you are saying. This is an esoteric subject for sure. For those of us that have a background in optics or in lens design, these cross sections can tell us how modern or primitive the designs are. They can also show us how similar they are to other lens makers.
07-24-2015, 01:13 PM   #10
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QuoteOriginally posted by gofour3 Quote
the 6x7 are as follows:
07-01-2018, 11:36 AM   #11
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I have not found much on the newer 645 lenses, but the Pentax litearture includes a cross-section of the camera with the 55mm AL SDM AW lens mounted. This provides a clue about the double-gauss design of that lens.

This image has been posted in many other places, but perhaps it should also be here for those wondering about at least one of the newer lenses.

RicK "for posterity" Denney
07-01-2018, 01:52 PM   #12

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It also shows the trapezoid prism and Keplarian finder.
07-01-2018, 11:03 PM - 1 Like   #13
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good share, thanks!

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