Pentax 645N shutter lines on negatives

tomfrh · Aug 9, 2016

Hi,

I have a 645n which has developed this problem, which appears common:

http://www.pentaxforums.com/forums/48-pentax-medium-format/174550-lines-645n-negatives.html

Presumably a curtain is sticking and causing the uneven exposure.

It happens randomly every so often.

Any hints?

Tom

winger · Aug 9, 2016

As in the linked thread, it may be time for a CLA. From Australia, I'm not sure if it's worth sending it to the USA for servicing - is there a good Pentax repair person there?

Aaron Ross · Mar 28, 2018

Hello, did you ever find a solution? I am experiencing the exact same problem. Although I recently changed the batteries and the new roll i've shot doesn't have this issue on it at all. Not sure if they're related.
https://www.flickr.com/groups/28504109@N00/discuss/72157693051826071/72157694249404784/

wiltw · Mar 28, 2018

NOT a developer filling issue no hard edged well defined LINE would demark the transition of two fills!

Not an issue about curtain travel being 'inconsistent', else one would see multiple zones of higher and lower density as the slit moved inconsistently (slower in some places, faster in others) across the film plane.

I would say that the first curtain moves across first, but the second curtain gets initally delayed in its progression across the film plane...causing the first half of the area to get higher density than the second half

pentaxuser · Mar 28, 2018

tomfrh, I am a P645N owner myself. If a CLA cures it or whatever cures it, let us know please. Unfortunately the person with what seemed to be the same problem on Pentaxforums hasn't said what cured the problem either and is never likely to, given it is now over 5 years ago.

pentaxuser

tomfrh · Mar 28, 2018

Aaron,

The issue went away by itself, so I never got the bottom of it. I don’t recall if it went away after changing batteries.

tomfrh · Jul 11, 2018

This problem came back with my 645N. I've figured it out now.

It’s not the shutter, it's a light leak where the back meets the body.

Light gets thru the gap and shines on the most recently shot frame, which is partially rolled up onto the top reel. The line is a shadow cast by the reel. See this diagram.

SOLUTION: New seals, or a new back, or black electrical tape to seal up your leaky gaps.

Aaron Ross · Jul 11, 2018

Awesome! I thought it must be from something like that.
Did you get new seals for it? Not sure how to go about doing that. Would hate to have to tape it up every time I change a roll.

tomfrh · Jul 12, 2018

Aaron Ross said:
Awesome! I thought it must be from something like that.
Did you get new seals for it? Not sure how to go about doing that. Would hate to have to tape it up every time I change a roll.

I got another back, but you can buy pentax 645 light seals on ebay. They're foam strips that sit inside a slot.

Pentax 645N shutter lines on negatives

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