[TJswe]

Hi!

Im new to the analog world and stepped into it with a Pentax 6x7 camera. First roll came out good a few months ago but when i picked up the next three rolls today something has happened.

Half of some of the images are black. Its not all on a roll, first is good, three bad and two good and so on.

See my attached image for an example. What happened. Since they are black my first thought goes to the shutter...

Anyone have a clue?

Attached Images

 

[TomB_tx]

Classic case of "shutter-capping" - where the 2nd (closing) shutter curtain catches up with the 1st (opening) curtain before the 1st gets across the frame. The travel speed of each curtain depends on the condition of the bearing lubricants (light oil usually), dirt that can cause binding, and spring tension. As a camera gets old the lubes dry out, and may either get sticky and slow down a shutter, or lose the damping film of oil and allow a curtain to move too fast. Poor lubrication (and dirt) also cause erratic speeds, where it varies shot to shot - like you have. Capping is more of an issue with fast shutter speeds, where the opening between the curtains is narrower. Sometimes people just use slower speeds to avoid it rather than get it fixed.
Tripping the shutter a lot (without film) sometimes improves the condition - but is a temporary fix.
The camera needs a "CLA" : Clean, Adjust, Lubricate by a good technician like Eric Hendrickson. Cleaning involves significant dis-assembly to clean out the old crud, then re-lubing with the correct very light oils (and greases on some parts), then adjustment of the springs while measuring the curtain travel times, and finally setting the shutter speeds.
If you are located in the US or Canada, Eric is the best available. He repaired my 6x7 (as well as several 35mm bodies) and his work is always top-notch and less expensive than most places. (But the 6x7 does cost more than a 35mm to service).

[TJswe]

Thank you very much for a quick and detailed answer!

That sounds like the problem for sure.

Yes i have read about the magic from Mr Hendrickson, but unfortunately im in Sweden so shipping this lump of metal is perhaps not my first option.

Thanks again!

/Thomas