Pentax 645 - Loose lens mount - can't remove top cover to fix it

Dr.Ross · 12-25-2021, 03:32 PM

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Originally posted by jay_2791

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

Jay. I am new to the Forum. I read your post. I am having a similar challenge with removing the camera top. Could you please, review how you removed the camera top?

I want to change some plastic film loading gears: they are badly stripped. I have a good set from a donor 645. But, I must remove the top camera cover to replace the gears at the left side of the camera.

jay_2791 · 01-14-2022, 09:39 AM

Originally posted by Dr.Ross

Jay. I am new to the Forum. I read your post. I am having a similar challenge with removing the camera top. Could you please, review how you removed the camera top?

I want to change some plastic film loading gears: they are badly stripped. I have a good set from a donor 645. But, I must remove the top camera cover to replace the gears at the left side of the camera.

Hi there!
Sorry for the delay in replying.
I'm afraid I can't help you that much :/
I wasn't able (and didn't have to) to remove the viewfinder to tighten the lens mount screws. I have a 2nd 645 that needs a bigger intervention, but I have not made that jump just yet.
Are you stuck with the viewfinder as well?

elmo · 05-07-2022, 04:04 AM

Following up a bit on the 645 battery holder discussion.

Yesterday I stumbled upon a French Ebay listing from a seller that is selling 3D printed battery holders. He gets around the difficult issue of contacts by switching from 6xAA to 2x9v batteries, with the standard clip-on contacts. That's thinking outside the box. At first I was excited: wow, lots of stored energy. Wired in parallel, it's still the required 9v, but with TWO batteries. OK, this WILL work for someone with no battery holder, but, it will not be ideal, as I have Googled a bit, and found that 9v batteries carry significantly less energy than AA cells, to begin with.

6xAA alkaline batteries have about 4x more energy than 1x9v alkaline. So, 2x9v is still about half of what a standard 645 battery pack would hold. Then, there are lithium 9v batteries, which might make up for some of that deficit.

Energy Density of 9V battery vs. AA batteries - Bald Engineer

Here's the current listing, which has the price of a battery holder at about US$60 delivered:
Battery holder pentax 645-battery case for pentax 645 - 9v-wired & ready | eBay

I first noticed this when looking at a listing from a guy that bought one, but found his 645 to be dead, so is selling on the battery holder he had bought from the Ebay seller, $40 delivered:
Battery holder / case / compartment for Pentax 645 9v-wired & ready - 3D printed | eBay

Those links will eventually die, so, here are a few pics from the Ebay seller's listing.

sforsythe05 · 01-18-2023, 08:01 AM

Hey there!

I know it's been a while since this thread was active. But I wanted to check if you managed to get the top cover of your Pentax 645 off. My 645's diopter screw has come loose inside and I need to open it up and screw it back in. However I'm not sure where all the screws are to get the cover off. This seems to be the only place with the hint of an answer haha. But if you figured it out and are willing to share the info I'd be super grateful.

Cheers!
Si

jay_2791 · 01-22-2023, 02:24 AM

Originally posted by elmo

Following up a bit on the 645 battery holder discussion.

Yesterday I stumbled upon a French Ebay listing from a seller that is selling 3D printed battery holders. He gets around the difficult issue of contacts by switching from 6xAA to 2x9v batteries, with the standard clip-on contacts. That's thinking outside the box. At first I was excited: wow, lots of stored energy. Wired in parallel, it's still the required 9v, but with TWO batteries. OK, this WILL work for someone with no battery holder, but, it will not be ideal, as I have Googled a bit, and found that 9v batteries carry significantly less energy than AA cells, to begin with.

6xAA alkaline batteries have about 4x more energy than 1x9v alkaline. So, 2x9v is still about half of what a standard 645 battery pack would hold. Then, there are lithium 9v batteries, which might make up for some of that deficit.

Energy Density of 9V battery vs. AA batteries - Bald Engineer

Here's the current listing, which has the price of a battery holder at about US$60 delivered:
Battery holder pentax 645-battery case for pentax 645 - 9v-wired & ready | eBay

I first noticed this when looking at a listing from a guy that bought one, but found his 645 to be dead, so is selling on the battery holder he had bought from the Ebay seller, $40 delivered:
Battery holder / case / compartment for Pentax 645 9v-wired & ready - 3D printed | eBay

Those links will eventually die, so, here are a few pics from the Ebay seller's listing.

Wow! I missed this post. Very interesting information!
This 645 has been in the back burner for a very long time, since it looks like there's a problem with the shutter button as well :/
That, and the 100+ cameras I'm going through 😄
I've been toying with the idea of using Nikon 7.2v batteries with a dc-dc converter, but there are several things to consider before that. We'll see.
J

---------- Post added 01-22-23 at 02:27 AM ----------

Originally posted by sforsythe05

Hey there!

I know it's been a while since this thread was active. But I wanted to check if you managed to get the top cover of your Pentax 645 off. My 645's diopter screw has come loose inside and I need to open it up and screw it back in. However I'm not sure where all the screws are to get the cover off. This seems to be the only place with the hint of an answer haha. But if you figured it out and are willing to share the info I'd be super grateful.

Cheers!
Si

Hi there!
It has been a while, but as far as I remember there are a couple of screws on or underneath the side covers, and one or more at the top underneath the hotshoe. There may be another pair next to the eyepiece, but I may be confusing it with another camera.

05-07-2022, 04:04 AM	#18
elmo New Member Join Date: Dec 2019 Posts: 9	3D printed 645 battery holder with 2x9v batteries Following up a bit on the 645 battery holder discussion. Yesterday I stumbled upon a French Ebay listing from a seller that is selling 3D printed battery holders. He gets around the difficult issue of contacts by switching from 6xAA to 2x9v batteries, with the standard clip-on contacts. That's thinking outside the box. At first I was excited: wow, lots of stored energy. Wired in parallel, it's still the required 9v, but with TWO batteries. OK, this WILL work for someone with no battery holder, but, it will not be ideal, as I have Googled a bit, and found that 9v batteries carry significantly less energy than AA cells, to begin with. 6xAA alkaline batteries have about 4x more energy than 1x9v alkaline. So, 2x9v is still about half of what a standard 645 battery pack would hold. Then, there are lithium 9v batteries, which might make up for some of that deficit. Energy Density of 9V battery vs. AA batteries - Bald Engineer Here's the current listing, which has the price of a battery holder at about US$60 delivered: Battery holder pentax 645-battery case for pentax 645 - 9v-wired & ready \| eBay I first noticed this when looking at a listing from a guy that bought one, but found his 645 to be dead, so is selling on the battery holder he had bought from the Ebay seller, $40 delivered: Battery holder / case / compartment for Pentax 645 9v-wired & ready - 3D printed \| eBay Those links will eventually die, so, here are a few pics from the Ebay seller's listing. Attached Images

01-18-2023, 08:01 AM	#19
sforsythe05 New Member Join Date: Jan 2023 Posts: 1	Diopter has come loose Hey there! I know it's been a while since this thread was active. But I wanted to check if you managed to get the top cover of your Pentax 645 off. My 645's diopter screw has come loose inside and I need to open it up and screw it back in. However I'm not sure where all the screws are to get the cover off. This seems to be the only place with the hint of an answer haha. But if you figured it out and are willing to share the info I'd be super grateful. Cheers! Si

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12-25-2021, 03:32 PM	#16
Dr.Ross New Member Join Date: Dec 2021 Posts: 4	Staff note: This post may contain affiliate links, which means Pentax Forums may earn a small commission if a visitor clicks through and makes a purchase. If you would like to support the forum directly, you may also make a donation here. Originally posted by jay_2791 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 Jay. I am new to the Forum. I read your post. I am having a similar challenge with removing the camera top. Could you please, review how you removed the camera top? I want to change some plastic film loading gears: they are badly stripped. I have a good set from a donor 645. But, I must remove the top camera cover to replace the gears at the left side of the camera.

01-14-2022, 09:39 AM	#17
jay_2791 New Member Join Date: Oct 2019 Location: Michigan Posts: 11 Original Poster	Originally posted by Dr.Ross Jay. I am new to the Forum. I read your post. I am having a similar challenge with removing the camera top. Could you please, review how you removed the camera top? I want to change some plastic film loading gears: they are badly stripped. I have a good set from a donor 645. But, I must remove the top camera cover to replace the gears at the left side of the camera. Hi there! Sorry for the delay in replying. I'm afraid I can't help you that much :/ I wasn't able (and didn't have to) to remove the viewfinder to tighten the lens mount screws. I have a 2nd 645 that needs a bigger intervention, but I have not made that jump just yet. Are you stuck with the viewfinder as well?

01-22-2023, 02:24 AM	#20
jay_2791 New Member Join Date: Oct 2019 Location: Michigan Posts: 11 Original Poster	Originally posted by elmo Following up a bit on the 645 battery holder discussion. Yesterday I stumbled upon a French Ebay listing from a seller that is selling 3D printed battery holders. He gets around the difficult issue of contacts by switching from 6xAA to 2x9v batteries, with the standard clip-on contacts. That's thinking outside the box. At first I was excited: wow, lots of stored energy. Wired in parallel, it's still the required 9v, but with TWO batteries. OK, this WILL work for someone with no battery holder, but, it will not be ideal, as I have Googled a bit, and found that 9v batteries carry significantly less energy than AA cells, to begin with. 6xAA alkaline batteries have about 4x more energy than 1x9v alkaline. So, 2x9v is still about half of what a standard 645 battery pack would hold. Then, there are lithium 9v batteries, which might make up for some of that deficit. Energy Density of 9V battery vs. AA batteries - Bald Engineer Here's the current listing, which has the price of a battery holder at about US$60 delivered: Battery holder pentax 645-battery case for pentax 645 - 9v-wired & ready \| eBay I first noticed this when looking at a listing from a guy that bought one, but found his 645 to be dead, so is selling on the battery holder he had bought from the Ebay seller, $40 delivered: Battery holder / case / compartment for Pentax 645 9v-wired & ready - 3D printed \| eBay Those links will eventually die, so, here are a few pics from the Ebay seller's listing. Wow! I missed this post. Very interesting information! This 645 has been in the back burner for a very long time, since it looks like there's a problem with the shutter button as well :/ That, and the 100+ cameras I'm going through 😄 I've been toying with the idea of using Nikon 7.2v batteries with a dc-dc converter, but there are several things to consider before that. We'll see. J ---------- Post added 01-22-23 at 02:27 AM ---------- Originally posted by sforsythe05 Hey there! I know it's been a while since this thread was active. But I wanted to check if you managed to get the top cover of your Pentax 645 off. My 645's diopter screw has come loose inside and I need to open it up and screw it back in. However I'm not sure where all the screws are to get the cover off. This seems to be the only place with the hint of an answer haha. But if you figured it out and are willing to share the info I'd be super grateful. Cheers! Si Hi there! It has been a while, but as far as I remember there are a couple of screws on or underneath the side covers, and one or more at the top underneath the hotshoe. There may be another pair next to the eyepiece, but I may be confusing it with another camera.