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Old 8th March 2020, 07:01 AM
BarryRaynsfor BarryRaynsfor is offline
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Default Pentax 67 prism finder problem

Hi,can anyone help please.Just noticed in my prism finder there appears to be what I presume is fungus present.There is one larger piece and some spiders web type strands.Has anyone experience of taking this prism apart and cleaning it or is it best to leave to the experts ? If this is the case could a suitable repairer be recommended.Many thanks.
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Old 8th March 2020, 10:17 AM
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B&W Neil B&W Neil is offline
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Originally Posted by BarryRaynsfor View Post
Hi,can anyone help please.Just noticed in my prism finder there appears to be what I presume is fungus present.There is one larger piece and some spiders web type strands.Has anyone experience of taking this prism apart and cleaning it or is it best to leave to the experts ? If this is the case could a suitable repairer be recommended.Many thanks.

Taking the prism apart could be tricky so unless someone here has done this job and can advise on what's involved I would leave the job to the experts.

If the camera has not been serviced for a while it would probably be cost effective to book it in for a service and ask them to clean up the prism at the same time (this may well be include).

The Pentax 67 is a great camera and some TLC with an expert would be money well spent.

Neil.
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Old 8th March 2020, 12:58 PM
mpirie mpirie is offline
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Are you sure it's fungus? If it is, then exposure to strong sunlight could diminish it.

My worry would be that the strands could be corrosion of the silvering that's applied to the prism glass. Normally it starts at an edge and works it's way inwards.

I'm sure the prism could be resilvered if this is the problem, but the cost may be prohibitive.

Mike
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Old 8th March 2020, 04:33 PM
BarryRaynsfor BarryRaynsfor is offline
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Default Pentax 67 Prism

Hello and many thanks for the replies and suggestions.I have attempted to photograph the fungus like material in the hope it may help identification. It is shown at the tip of my finger.
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Old 8th March 2020, 05:15 PM
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Hello and many thanks for the replies and suggestions.I have attempted to photograph the fungus like material in the hope it may help identification. It is shown at the tip of my finger.

This looks rather dark to me to be fungus, but I may well be wrong.

It also looks rather solid whereas the fungus I've seen has been has been more thread like white-out a solid core.

I am beginning to think this could well be silver lifting away from a mirrored surface - and I hope I am wrong.

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Old 8th March 2020, 05:32 PM
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It could be foam in the prism housing deteriorating through age. I’ve had this with Olympus and Nikkormat cameras. It’s the same problem you get with light seals. There is sometimes a piece of foam located on top of the prism which turns to a black mush. The edges of the housing look like they have some sort of issue with the light seals. Professional cleaning and service is, as Neil says, your best bet.
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Old 8th March 2020, 05:38 PM
Richard Gould Richard Gould is offline
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I have to agree with Neil and Mike, this does nt look like Fungus to me, it is way to dark, looks more like de silvering starting, and best to get it sorted at a repairer rather than trying to take the prism apart yourself
Richard
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Old 8th March 2020, 06:36 PM
BarryRaynsfor BarryRaynsfor is offline
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Default Pentax 67 Prism

Many thanks for the replies on this subject.I agree this is a job for the experts ! If anyone could recommend a repairer for this work I would be pleased to have details.Thank you.
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Old 8th March 2020, 06:38 PM
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It could be foam in the prism housing deteriorating through age. I’ve had this with Olympus and Nikkormat cameras. It’s the same problem you get with light seals. There is sometimes a piece of foam located on top of the prism which turns to a black mush. The edges of the housing look like they have some sort of issue with the light seals. Professional cleaning and service is, as Neil says, your best bet.
Alex.


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Good point Alex.

I have sreen this when I have been replacing old light seals and you are right - they end up as a black sticky / oily substance that can drop anywhere.


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