Mamiya Prismat with stuck/seized 100mm lens

tikkathreebarrel

tikkathreebarrel

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Working my way through "do I keep it or do I sell it" I came across a lens in a case. It's a 100mm lens for the really quirky Mamiya Prismat CPH, see here for information:
http://herron.50megs.com/prismat.htm
This lens came with a camera and the odd thing about the lens is that it's either seized or been locked at infinity focus.
So, the time came to see whether it worked and just how bad the fixed focus might be. Much inside forty feet it isn't in focus but see what you think:

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Interesting camera, definitely worth keeping and probably a CLA if you want to get the most out of it.
 
I've heard of greese turning cemnty, maybe that's its issue?
 
pingu666 said:
I've heard of greese turning cemnty, maybe that's its issue?
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Well I cannot move the lens at all so it could be hard grease but given that it's locked at infinity rather than at some random distance ---- yes I accept that infinity could be equally random ---- but I don't want to risk dismantling something that I might not be able to re-assemble, I'm wimping out with the molegrips.:bonk:
 
RaglanSurf said:
Interesting camera, definitely worth keeping and probably a CLA if you want to get the most out of it.
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I'm having such a clear out but I have a perverse affection for the Prismat partly for the unique lens mount, partly for the delicious kerlopp sound the shutter makes. The standard 50mm lens is a 1.9 lens.

That's the trouble with shoving a film in something I ought be rationalising out:cuckoo::cuckoo: Okay, you've won me over, the Prismat stays.
 
you could reasearch heating it too, might do something...., infinity is normaly the shortest physical size, so makes sense that it was put on infinity, put away and then got seized somehow?
or someone tried to wind past the stop :-O
 
pingu666 said:
you could reasearch heating it too, might do something...., infinity is normaly the shortest physical size, so makes sense that it was put on infinity, put away and then got seized somehow?
or someone tried to wind past the stop :-O
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Hmm. Maybe I'll sit it on a radiator for an hour ande see what that does.:nuts:
 
Heat normally expands, cold normally contracts?

I would pop it in the fridge wrapped in a tight cover of cling film for an hour and then see if free,s itself on the turn of the focus ring.
 
heat would warm up the lubrication, and make it thinner, and easier to move, cold would do opposite, but would give contraction vs expansion :)
 
Well it seems to me that with any lens that is hard to focus, it's usually because the grease has solidified, or maybe it was dropped sometime. You could try a tiny bit of penetrating oil but don't blame me if it got onto the lens. :(
 
excalibur2 said:
Well it seems to me that with any lens that is hard to focus, it's usually because the grease has solidified, or maybe it was dropped sometime. You could try a tiny bit of penetrating oil but don't blame me if it got onto the lens. :(
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Oh no? You would be completely blameworthy my friend. :clap::clap:

Tried sitting it on a domestic radiator for an hour yesterday and no movement, I'll give it another go tonight.

Here are a few shots with Rollei Retro ASA 100: love this film:love:

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Hey tikkathreebarrel it's about time you entered the photo challenge, as your shots are worthy to be entered.
 
I have acquired this camera recently, can anyone tell me if they know where to find a manual for it? And how the light meter works?
Thanks :)
 
clorgan said:
I have acquired this camera recently, can anyone tell me if they know where to find a manual for it? And how the light meter works?
Thanks :)
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Hi Claire, welcome to the best bit of the TP forum.

The best place to look for manuals is Buktus's website http://www.butkus.org/chinon/index.html

It may take a little searching depending on which Prismat you have as there are manuals for different versions depending on where it was sold.
 
If the lens is stuck then, apart frmo the grease already mentioned, it could be that the helicoil is broken so I doubt any amount of heating and frezzing will free it up.

I had a Nikon lens like that which was getting very very hard to turn then just stopped. Took it to one place "Nar mate helicoil is broken the lens is knackerd as there are no parts", so keep using it and contacted another place and they said "Send it over and we'll have a look" so off it went and was away for about 5 or 6 weeks, then came back all fixed, was well chuffed and it has been fine ever since.
 
Knikki said:
If the lens is stuck then, apart frmo the grease already mentioned, it could be that the helicoil is broken so I doubt any amount of heating and frezzing will free it up.

I had a Nikon lens like that which was getting very very hard to turn then just stopped. Took it to one place "Nar mate helicoil is broken the lens is knackerd as there are no parts", so keep using it and contacted another place and they said "Send it over and we'll have a look" so off it went and was away for about 5 or 6 weeks, then came back all fixed, was well chuffed and it has been fine ever since.
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Since we're on the subject, do you (or anyone else) have somewhere they'd recommend sending lenses for service? Ideally somewhere that's comfortable with Nikon lenses I suppose. I once sent a lens off to Fixation (http://www.fixationuk.com/Fixation/Repairs.html) for repair - they were very competent but a bit pricey and I'd like to consider alternatives for a couple of lenses that need a bit of TLC.
 
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