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12-13-2019, 03:49 AM   #1
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Pentax 67 - Light leaks or what ??

Hi all,

I want to ask you about a problem which I faced several times.
I believe that the conclusion is not obvious, but who knows.
Last time I have observed that on some frames only in vertical position (portrait) there is uneven exposition. I have attached some samples in order to show you what is going on.
My first thought was that something went wrong during process (currently I use JOBO processor), but the space around the frame doesn’t contain this strange issue – simply saying We can observe it only in visible frame.
Second conclusion was that the shutter has some problems – this option was checked in service, and it seems to be ok with every time.
What is this?
Could you please shed some light on it ?

Kind regards
Marek

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12-13-2019, 07:19 AM   #2
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Does it show up on every frame?
Does it show up with with different lenses?
Does it occur when the camera is held in the normal horizontal orientation, instead of in a vertical direction like the 3 examples above?
12-13-2019, 07:44 AM   #3
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Pentax 6x7 negatives are oriented horizontally on the film, and the shutter moves horizontally. Therefore this is probably not something related to the shutter. Had the shutter curtains moved at different speeds, the line would have been oriented in a direction perpendicular to this one. Maybe it is related to the development of the film?
12-13-2019, 08:06 AM   #4
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Mentioned issue appears only on vertical frames.
Sometimes I get one or two per roll.
Regarding lenses - with 105@2.4 and 75@4.5 too - but I don't think that it is lens related issue.

12-13-2019, 09:54 AM   #5
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It doesn't look like a light leak to me. Light leaks are usually way over exposed areas that don't have such a defining edge like that. But never say never. I develop my own color film and I've had similar looking issues like that now and then but not with such a defining edge. Was the woman taken with the camera held 180 deg different than the kids? If so I'd say it's that's a clue. Can't say what though.
12-13-2019, 12:51 PM   #6
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Definitely not a light leak. The line isn't parallel to an edge which makes it unlikely to be a curtain travel issue.
12-13-2019, 01:24 PM   #7
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The mirror moves in that direction. It has a distinct edge across the whole frame as it swings up.
12-13-2019, 04:34 PM   #8
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There are similarities to another thread showing an apparent overlap of frames which are thought to be the result of film processing (roller transport). Shutter faults are more likely to show as quite large vacant, overexposed areas, or areas with no exposure at all. Light leaks show up as comet-like spots or streaks at the top or bottom (less common in central areas of the frame), and are most commonly seen when poor loading or unloading of 120 rolls is done.

I suggest you run two more rolls through the camera, and take one roll to your usual processing facility, and the other to a processing facility you have not used before. Report back with your findings. Do not assume that the camera is always at fault, although the very old Pentax 6x7 cameras from the late-1960s are over-represented in age-related problems.

12-14-2019, 03:58 AM   #9
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Thank you for sharing some thoughts.
I don't assume that this is camera only related issue.
But, let's assume that this is processing fault so how is it possible that on empty negative in between frames there are no any issue appear?
12-14-2019, 09:44 AM   #10
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QuoteOriginally posted by marektrz Quote
...
But, let's assume that this is processing fault so how is it possible that on empty negative in between frames there are no any issue appear?
Because there is no exposure on the area between the frames for the developer to work on to create a development difference maybe. And let's keep that in mind. 1/3 of the frame is getting more exposure or more development. And to get more development with such a defining boundary is odd. Can you see the difference on the negative? Are you scanning the images? If not maybe that's is where the source of the problem is.

Last edited by tuco; 12-14-2019 at 10:05 AM.
12-14-2019, 11:57 AM   #11
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QuoteOriginally posted by tuco Quote
Can you see the difference on the negative? Are you scanning the images? If not maybe that's is where the source of the problem is.
Yes, the difference is quite visible on the negatves. I am scanning the negatives too, but it is no relevant here.

Also I don't know how to explain so straight line even if I would agree with process faults.

And there is one thing which is worth to add here, that such issue is color process related only. With BW process I have no problems.
12-14-2019, 12:28 PM   #12
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It's so consistent and defining that I'm inclined to rule out random or human error from developing with a process where you wrap the film on a reel and develop in a small tank especially if you get more than one frame per roll of this problem.
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