Scratched negatives on Zorki II (and disassembly)

[henryvk]

Okidoki, I got another one.

I have shot two rolls with this Zorki II which is overall in very good shape and on both rolls the last handful of frames have a scratch running through them.

The scratch meanders a bit, it even splits and converges again, and then it runs out before the roll is full.

Now, what could cause this? The fact that they don't show up until the roll is almost done makes me think it's on the take-up spool side but I can't see anything amiss there and the scratches must be on the emulsion side.

Ordinarily I'd check the film gate but unfortunately I haven't been abled to remove the outer shell because the button for the (Kiev-style) self-timer is in the way. So basically I have two questions: Does anyone have a good guess what causes these kinds of scratches? And how do you remove the damn self-timer? On a Kiev you don't need to because you can open the back and on a Zorki 1 you can just pull the outer shell off because it doesn't have a self-timer, so what do I do here? I can't find any guides online on how to disassemble this, admittedly, somewhat rare camera. Pushing the button to the right doesn't allow it to slip through the opening, it actually seems to big to go through. Can't see any way to get at it from the bottom either.

 

[Alan Johnson]

maizenberg-cameras : Isaak S. Maizenberg : Free Download, Borrow, and Streaming : Internet Archive

All You Need to Know about the Design and Repair of Russian Cameras

archive.org

Did you see this one? Maybe it unscrews.

 

[henryvk]

That's amazing! You just happend to know about this manual, right? Because it doesn't seem to be indexed in any way so that the even the archive.org search spits it out when querying "zorki 2", "zorki-2" or even just "zorki".

Anyway, thank you from a slightly embarassed head librarian.

 

[Mr Flibble]

Maizenberg's book is now also available as a print-on-demand from Amazon about 10 bucks.
Just picked it up myself.

My guess is that a part of the surface on the back of the shutter crate has oxidized, causing the scratch.

 

[henryvk]

My guess is that a part of the surface on the back of the shutter crate has oxidized, causing the scratch.

Now that I think about it, the scratch meandering can be caused by slight up and down movement of the film as it's being pulled along.

I'll hopefully have some time to disassemble this weekend, then we'll know for sure.

 

[henryvk]

I present to you the culprit. A bump from an imperfection in the casting on the back of the curtain box/film plane. Since it's got burrs/edges facing multiple ways, I'm 95% sure this is what caused the scratches.

The finish is very rustic, to say the least, just look at the edge of the film gate. Even with Zorkis it's not usually *this* crude.

Anyway, I planed and polished it away with the dremel tool and now the surface is smooth.

While I was in there, I cleaned out the gears of the right side curtain drum. This is where all the gunk and slivers of torn-off film tend to gather and now, as a bonus, the winding is noticeably smoother.

@mods: This ought to be moved to the rangefinder subforum.

 

[Mr Flibble]

That does strike me as unnaturally crude, even for Zorkis sold on the home market.
But that does indeed look like you found the source of those scratches.

You might want to smooth over the outside edges of the shutter crate as well, where the film leaves the cartridge and where the film goes onto the sprocket wheels.