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08-18-2018, 11:12 AM   #1
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All images from Pentax 6x7 out of focus

Title is pretty self explanatory. I purchased a 6x7 from Japan and it arrived very well packaged, although there is a noticeable ding on the metered viewfinder. I shot maybe two rolls through it using multiple lenses, but when I scanned them into the computer everything was out of focus. (I have scanned other medium format film with this scanner and the focus is spot on.) When framing the shot through the viewfinder everything was in focus. I've communicated with the seller but by that time it was too late to return the camera.

So here's my question. Is it possible that when the viewfinder received it's ding that it shifted something inside that causes the image to be out of focus because I'm compensating for the issue? Do you think I should look for another viewfinder or try and sell the camera for parts and get a different body?

Attached images: a quick scan showing the type of focus I was getting, and a picture of the ding on the viewfinder.

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08-18-2018, 11:42 AM   #2
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Love the AOC prism, btw - I'd say that that ding was almost certainly enough to shift the seating of the prism, which could (I think) affect focusing. The only other thing I can think of immediately is the dioptre compensation, but I don't know that that would result in wrongly focused pictures that appeared sharo through the viewfinder. One other possibility, though the prism looks like the natural suspect - is the mirror - I had an LX where the mirror was slightly out of alignment and the result is out of focus pictures
08-18-2018, 12:04 PM   #3
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As ffking stated it is probably the prism but if you want to definitively rule out your scanner or other problems and have the time run another roll of film through the camera with only distant subjects so that you can focus manually on infinity -- if the scans are still out of focus you've probably ruled out the scanner. A third and probably unlikely possibility is that the back pressure plate the film rests on is slightly off kilter giving you bottom in focus, top out of focus like you see in your pic (are all the shots out of focus in exactly the same way?).
08-18-2018, 12:21 PM   #4
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QuoteOriginally posted by travelswsage Quote
As ffking stated it is probably the prism but if you want to definitively rule out your scanner or other problems and have the time run another roll of film through the camera with only distant subjects so that you can focus manually on infinity -- if the scans are still out of focus you've probably ruled out the scanner. A third and probably unlikely possibility is that the back pressure plate the film rests on is slightly off kilter giving you bottom in focus, top out of focus like you see in your pic (are all the shots out of focus in exactly the same way?).
I'll attach another image for you. In the case of the image shown, I focused on the numbers written on the house.

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08-18-2018, 12:22 PM   #5
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QuoteOriginally posted by ffking Quote
Love the AOC prism, btw - I'd say that that ding was almost certainly enough to shift the seating of the prism, which could (I think) affect focusing. The only other thing I can think of immediately is the dioptre compensation, but I don't know that that would result in wrongly focused pictures that appeared sharo through the viewfinder. One other possibility, though the prism looks like the natural suspect - is the mirror - I had an LX where the mirror was slightly out of alignment and the result is out of focus pictures
How likely do you think the mirror option is?
08-18-2018, 12:38 PM - 1 Like   #6
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Since the prism is removable I would chuck it and get a new one. Your 6x7 body is probably fine and you just need a new prism.

Phil.
08-18-2018, 01:04 PM - 1 Like   #7
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Also worth pointing out, you can shoot without the prism on, looking directly at the ground glass. It might be worth shooting a test roll with a clear subject, on a tripod. Then you’ve taken the finder out of the equation. (Be sure the take the lens off before removing and replacing the TTL finder.)

08-18-2018, 01:06 PM - 1 Like   #8
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QuoteOriginally posted by Sedrick Quote
How likely do you think the mirror option is?
The mirror is a very viable part. I had the same issue with my LX. Using another camera and the distance scales, I determined the focus was off by 3 feet average. When I took it in for repair, my repair man told me the seating for the mirror was off on one side and needed adjustment. He also said it was common for Pentax cameras of that age to have the issue if they get dropped or jarred.

He had it adjusted and back to me the next day.
08-18-2018, 01:07 PM   #9
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QuoteOriginally posted by Sedrick Quote
How likely do you think the mirror option is?
I'd say it's far less likely than the prism, just a back-up if it's not the prism - as abruzzi says, try focusing on the ground glass without the prism - then you'll now if that's where the fault is.
08-18-2018, 01:14 PM - 1 Like   #10
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The prism is not the problem. The image is focused on the ground-glass screen, which is below the prism, mounted in the camera body. If, as you say, it looked sharp in the eyepiece, it must have been sharp on the screen. A misaligned prism can’t make an unsharp image on the screen appear sharp. It can only make a sharp image appear unsharp, but then all the details of the screen markings (like the line around the microprism spot) will also be unsharp.

You can prove this to yourself by removing the prism and inspecting the image directly on the ground glass using a loupe. Make a photo that way and see if it is sharp. (All the chimney finder is is a loupe mounted in a shade.)

And don’t assume anything about the scanner. Inspect the negative for sharpness on a light table using a strong (10x) loupe. If it is sharp there but the scan is soft, it’s the scanner no matter what it has done in the past.

If it’s in the camera, then either the screen isn’t properly seated (most likely), the film isn’t sitting properly in the camera, or the mirror isn’t sitting where it’s supposed to when it is down.

Make sure the selector is on 120, not 220. Probably not the issue, however.

Personally, I have bought 6x7’s with the built-in expectation of sending them to Eric for overhaul.

Rick “who has had dinged prisms in the past—worse than that one—that caused no issue” Denney

---------- Post added 08-18-18 at 04:18 PM ----------

QuoteOriginally posted by Sedrick Quote
I'll attach another image for you. In the case of the image shown, I focused on the numbers written on the house.


Well, it’s not the scanner. A scanner problem can’t move the focus plane.

Therefore, I’m back to suspecting the screen or reflex mirror adjustment.

Rick “send it to Eric” Denney
08-18-2018, 01:39 PM - 1 Like   #11
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Just my two cents worth. I think it could be the prism. I agree with the idea of using only the focus screen without the prism in place. I have used a loupe set directly on the top of the focus screen in the past when doing macro work with the 67. If you know it is dead nuts with a loupe and the process soft, then you have eliminated the prism as the problem. Be sure not to drop the film though, as the silver halide crystals can shake out of focus. (sorry about that last line, it was a common comment when I was in the processing business to explain a customers soft photos)
08-18-2018, 02:29 PM - 1 Like   #12
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QuoteOriginally posted by Dr Goodglass Quote
Be sure not to drop the film though, as the silver halide crystals can shake out of focus.
Ha ha ha! I'm going to treasure that one!
08-18-2018, 03:44 PM - 1 Like   #13
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I am suspicious of the focusing screen, not the prism.
When changed, the focusing screen must be carefully calibrated for focus at 3 points in the centre. It is not a drop-in-and-forget task. Or, if something like the meter coupling chain was broken and repairs were done, was the lens mount and focusing screen then collimated to specification? The possibility of a distorted mirror box comes to mind, but really, your best option is to have the camera professionally examined, even if the cost of doing so and any required repairs outstrip the net worth of the camera
08-18-2018, 05:25 PM   #14
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I just got an F3 back from the shop with a mirror misalignment fixed.
It caused the same problem.

One easy way to tell was that the lens focus scale distance was very different at minimum focus distance from where it seemed to be focusing. It also behaved the same way with or without a prism. And the F3 focus screens can’t really be put in wrong without it being obvious.

Humorously, the F3 also has a dented prism... maybe the prism dent is the sign of the hit that misaligned the mirror? Both caused by the same impact but unconnected from each other otherwise...

-Eric
08-18-2018, 05:39 PM   #15
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So now it seems you’re suspecting an issue with the mirror. In that case I have a few questions.

How much would I be looking at to repair this? I don’t have a ton of money right now.

Where could I get it repaired?

Would it be more cost effective to just sell it for parts and shop for a new body?
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