Black markings in finder of K1000

For Japanese devices JIS is generally what you want, and Vessel-brand screwdrivers can be had at a very good price.
https://www.amazon.com/dp/B000CED236

There are two sellers on eBay that have a prism replacement. The first seller is in Australia and states that the prism being sold is not a genuine Pentax part, whatever that means. The second seller is in the states but is selling the prism with the whole mirror box assembly and does state that there is normal wear and no extra information about the prism.

I am also looking over K1000 bodies for parts but no real idea if these bodies, many of them are dirt cheap, have prisms in them or if they may have been removed.

I am holding back with buying some tools until I can find a source for a prism with known condition. Would there be another brand of prism that would be compatible with the K1000 if I am unsuccessful in finding a Pentax one?

Thanks

What makes you think anything is wrong with the prism? Looks to me like a piece of foam has broken of and fell down and landed on the top of the focusing screen. All you need is set of Vessel JIS screwdrivers off ebay and a youtube video showing you how to take off the top panel and knobs so you can get to the topside of the focusing screen. Childs play. GL

F4U said:

What makes you think anything is wrong with the prism? Looks to me like a piece of foam has broken of and fell down and landed on the top of the focusing screen. All you need is set of Vessel JIS screwdrivers off ebay and a youtube video showing you how to take off the top panel and knobs so you can get to the topside of the focusing screen. Childs play. GL

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Desilvering was mentioned. When I looked up that term I saw the same condition that I have in my finder and it led me to threads talking about the prism needing to be replaced. I'm still new to all of this repair stuff. If it is just stuck foam then that will be a relief. What I'll do then is just get the screwdrivers and open up the top and see what is what. I'll keep updated.

What About Bob said:

Desilvering was mentioned. When I looked up that term I saw the same condition that I have in my finder and it led me to threads talking about the prism needing to be replaced. I'm still new to all of this repair stuff. If it is just stuck foam then that will be a relief. What I'll do then is just get the screwdrivers and open up the top and see what is what. I'll keep updated.

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Might be desilvering, but Idoubt it. I've worked on more camera than I can count and never seen desilvering look like that. Looks to me like a piece of foam has fallen on top of the focusing screen. All that old Japanese foam has decomposed and turns into a mess. The beauty is that the K1000 was a camera they made a trillion of. They're not a bad camera at all, but they have no market value. The only wat to find out is get a set of cheap JIS screwdrivers and maybe a cheap ebay spanner wrench set and open it up. Nice camera actually. I'm not disparaging it, so don't misunderstand. But for years it wast the most popular 35mm and they made a trillion of them. What have you got to lose by opening it up for a look-see? You can pick up another K1000 for practically nothhng.GL and Regards

The viewfinder photo you showed exhibits deteriorating polyurethane foam used for light sealing and as a top cushion between the pentaprism and the piece that holds it in place, There are light seals about the base of the prism where it sits in its receiver. The piece at the front edge of the focusing screen serves as a cushion. It decelerates the mirror at the top of its travel.

I see no evidence of a de-silvered prism. That looks quite different. I heard the following advice when I was young, “If it ain’t broke—don’t fix it.” It made sense then. It still does.

On the picture in the OP, you can see a symmetry line of sorts in the centre, with the sides of the black stuff slightly less in focus. That's the roof section on top of the pentaprism; the silvering has deteriorated in that area.

OAPOli said:

On the picture in the OP, you can see a symmetry line of sorts in the centre, with the sides of the black stuff slightly less in focus. That's the roof section on top of the pentaprism; the silvering has deteriorated in that area.

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I guess it could be desilvering along the top crest line of the prism, especially of the factory had put a layer of foam contact with it. The Japanese in all their design and manufacturing expertise made these fine instruments, but the devil mimself got in on the act with his foam. God thing this was about the most popular SLR to come out of Japan. Plenty of parts cameras cheap as dirt.

What About Bob said:

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That's a pretty thorough video,
Doesn't look like there are any inner light seals.
How many different prism variations are there?

Chuck1 said:

That's a pretty thorough video,
Doesn't look like there are any inner light seals.
How many different prism variations are there?

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Good question. In my search for answers there are mixed views even from the same brand and model of camera depending on when they were made. For example: I have seen mentions of older K1000 prisms that may not fit right in newer K1000 bodies. Few other answers being that you could even extract a prism from a Canon 50E, an Elan II and a T50/70 and that should suffice. information is varied.

There is an eBay seller that will not be available until the 6th of this month. I will buy a nonworking K1000 body from him and see if it has the prism in it. I can also use the top plate from that body in place of mine that has the ding in it. In the meantime I will go over the video guides and documents again and in a few days the screwdriver set and other tools will come. I will take the top off the camera and inspect things. If the situation isn't desilvering then I can skip the prism quest and work with other things on the camera. If it is desilvering then I will use the prism from the ordered body from eBay, if it has one. If not it will have the top plate and I can save whatever is left from that body that might come in handy later down the line.

Prisms by themselves do not seem plentiful on eBay, only found two possible sellers. Whatever online searches I try lead me mostly to message forums on desilvering. If there is an outlet that supplies such things I haven't found it yet. My guess is that a good amount of bodies should have the prisms in them and then it is a question of is that prism in the same state as the one you are trying to replace and the second question being will it fit?

Another good video. I think this is the same guy that I bought the Rolleicord from, back in August of 2019.

Looks like that body was sold. Just noticed it. I'll keep looking.

I have been waiting on a few eBay sellers for answers on junked K1000 bodies, different sellers than the others mentioned. It looks like I may have to write up a classified on here soon and see if anyone might have a spare prism. I will give it about a week and then post a classified. I'll keep updated.

I did get the tools in and will be getting a replacement top plate for the K1000.

I have a KM prism for AU$20 (US$13), plus postage, if that's any good to you.

On the Olympus OM1, one can just clean off the goop and the desilvered portion is hardly noticeable in the viewfinder.