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08-04-2022, 02:47 PM   #1
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hairline mark in PZ-1 viewfinder?

This is a weird issue I found on both copies of my PZ-1. I'm near sighted and always wear glasses. But when I take off my glasses, I can see a fine hairline mark in the middle of my viewfinder. It goes from up to the bottom and is almost right in the middle of the viewfinder, just like a fine line dividing the viewfinder into two portions. It seems to be inside the pentaprism. Anyone has a similar experience here? It has no effects on uses but I'm very curious what it is since both my PZ-1 have the exact same issue.

08-04-2022, 02:58 PM   #2
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prism desilvering?
08-04-2022, 04:27 PM   #3
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I've has a few pz-1 and pz-1p bodies with lines, usually outside the image area but not always. I don't know if its fungus or desilvering but its not uncommon. I've got about 3 bodies currently and only one without some defects.
08-04-2022, 08:36 PM   #4
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Can you take a picture of it? Iím really curious what it looks like now.

08-05-2022, 07:07 AM   #5
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I had one camera in which this was the case and it was a crack in the outermost glass window over the viewfinder eyepiece (very thin glass cover with no magnifying power). It could be seen from a distance but is out of focus and invisible when looking through the VF. Other than letting in some moisture and dust, it had no net effect on VF operation.

The other possibility is it's the line where the two roof prism planes come together which is dead centerline in the optics. If you look through the VF from a distance, you can see this line but looking through the prism in the normal fashion, it is completely invisible due to being out of focus. Again, this has no effect and is completely normal for a roof prism. See below (adapted from Wikipedia):
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Last edited by Bob 256; 08-05-2022 at 07:18 AM.
08-06-2022, 09:39 AM   #6
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If the line isn't visible when looking through the viewfinder normally, e.g. focusing or composing a shot, then I wouldn't worry about it. When you look through the viewfinder from a distance you are not focusing on the "virtual image" reflected from the mirror but rather the surfaces of the prism.
6 Days Ago   #7
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QuoteOriginally posted by Bob 256 Quote
I had one camera in which this was the case and it was a crack in the outermost glass window over the viewfinder eyepiece (very thin glass cover with no magnifying power). It could be seen from a distance but is out of focus and invisible when looking through the VF. Other than letting in some moisture and dust, it had no net effect on VF operation.

The other possibility is it's the line where the two roof prism planes come together which is dead centerline in the optics. If you look through the VF from a distance, you can see this line but looking through the prism in the normal fashion, it is completely invisible due to being out of focus. Again, this has no effect and is completely normal for a roof prism. See below (adapted from Wikipedia):
I think the second possibility is exactly my case. Both of my PZ-1 seem to have the line at the same position. It can only be seen from a distance or I take off my glasses. I tried to remove the focusing screen. Through the prism, I can see a vague fine line across the roof. Thanks for addressing my curiosity.
However, why I've never seen this on any other old SLR? Dark marks from aging are very common, though. This kind of line I've only seen on PZ-1.

5 Days Ago   #8
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QuoteOriginally posted by yubn93 Quote
I think the second possibility is exactly my case. Both of my PZ-1 seem to have the line at the same position. It can only be seen from a distance or I take off my glasses. I tried to remove the focusing screen. Through the prism, I can see a vague fine line across the roof. Thanks for addressing my curiosity.
However, why I've never seen this on any other old SLR? Dark marks from aging are very common, though. This kind of line I've only seen on PZ-1.
It depends on the prism and the other optics and if you have a true pentaprism prism with the roof section (I can't see the line in my K-1). The line images at a very close distance when looking through the VF and your eye is looking for an infinity image so the line (if it exists) is way out of focus. When you look through the VF from a few feet away, the virtual image of the line is just beyond the eyepiece which your focusing on so it comes into focus. Kind of like holding a thin wire in front of your eye while you focus on infinity in normal use, but if you move the wire to a couple of feet away and refocus on it, and it's clearly visible.
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