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10-13-2019, 08:40 PM   #1
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Join Date: Oct 2019
Location: Michigan
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Pentax 645 - Loose lens mount - can't remove top cover to fix it

Hello people,

I just added a Pentax 645 (original, not N) to my camera collection, and I need some help with it

I bought the camera from one of the traditional retailers for a small price, due to it being sold "as-is". The camera seems to be in very decent shape, with one exception: the lens mount is loose (it's also missing the grip, but that's another story). Before "investing" any more money on this setup, I want to make sure everything is working fine, and this implies fixing the lens mount.

I bought the 645's service manual (and then found it free somewhere else ), and managed to remove the bottom cover and tighten the *very* loose two bottom screws. Now I'm trying to get to the top two screws, but I can't make any sense of the instructions. Specifically, the instructions tell to remove three "A502" screws. Two are obvious, but there seems to be another one below the eyepiece (see image). If that's the case, the eyepiece (and the diopter adjusting ring) need to be removed. But:

I managed to remove the threaded tube containing the rear element of the eyepiece, but the diopter adjusting ring is *very* stiff, and I don't even know if it should come out by turning it or <?>. The ring was very stiff to begin with, but I have no idea how much -or how easily- it should turn.

I wonder if anyone around here has gutted one of these before and knows (and is willing to share) how to get the diopter adjusting ring and/or the top out - in a reversible manner



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Last edited by jay_2791; 10-14-2019 at 09:44 PM.
10-14-2019, 07:48 PM - 1 Like   #2
New Member

Join Date: Oct 2019
Location: Michigan
Posts: 3
Original Poster
Alright... I hate when this happens, but I'm somewhat glad it did: I have to answer my own question - at least partially.

I still don't know how far the "diopter ring" (the rubber-covered ring around the eyepiece) should turn in either direction, but at the end of the day it didn't matter. It wasn't necessary to remove the eyepiece at all.
The only thing preventing the top cover from moving far enough to be able to tighten the mount screws was one of the metal side covers. Tolerances are very high, and the increased resistance was enough to make me doubt myself-and the service manual.

In any case: the deed is done. Now I just need a battery grip - and a lens
Attached Images

Last edited by jay_2791; 10-14-2019 at 09:42 PM.

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645, bottom, camera, diopter, eyepiece, instructions, lens, lens mount, pentax, pentax service, repair, screws, service, warranty
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