Pentax 645N Dark Shadow on the Frames

Xiao · Jan 11, 2022

Hi,

This is my first time posting here, and also my first time owning a Pentax 645 camera.

After shooting a few rolls, I noticed there is sometime a dark shadow along one edge of the frames, in the shape of a trapezoid. So I took a look at the camera, and saw something hanging at the back of the shutter whenever it's open. And that piece seems causing the shadow.

Since I don't own any Pentax 645 camera before, I am not sure if that's serious or something perhaps I could get it fixed by myself?

Thanks,
Xiao

Sirius Glass · Jan 11, 2022

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Welcome to ~~APUG~~ Photrio!!

Would you post photographs of the negatives including the edges [rebates] of the file so that we can understand the problem more fully, please?

Xiao · Jan 11, 2022

Sure, here are two photos of the negatives, hopefully they are clear enough to see.

Deleted member 88956 · Jan 12, 2022

For sure your camera has an issue. There should be nothing in optical path that hangs like this. I will dig up my 645 N a little later and will post a pic what it should look like inside. If you bought it recently and can return it, I'd do it, or get seller to fix it.

Xiao · Jan 12, 2022

Hi VTLD,

Thanks a lot for your input. I never saw something like this before, and not sure what's happening there. Guess I'll send someone for repair, since I had it for sometime without taking many photos before. Hope it's nothing too serious.

Xiao

Deleted member 88956 · Jan 12, 2022

This is what it should look like. The piece that is hanging down on yours contains secondary mirror that does last moment off the film plane light check (I think), but should follow up and move out of the way before shutter fires (you can hardly see it when watching main mirror moving up and shutter fires). Might be an easy fix, unless something is actually broken and needs new part. Given that 645N is not THAT old yet, it should be a fairly easy job for a shop.

Deleted member 88956 · Jan 12, 2022

I would add, that you could try to gently pull that plate and see if it goes up (just gentle pull without trying to then push all the way up). It's possible that some debris is lodged in and keeps it from moving up. I don't know if this plate has electronically controlled time delay or there is just a mechanical escapement. This is first time I'm reading about such a problem, so it can't be common.

So, to repeat, a gentle pull (with finger) towards you will not hurt anything, so long as you do not force it, just slight nudge and see what happens. If it does pop up, then try releasing shutter seeral times to see if it hangs again or not. It does not cost anything, so worth a try.

itsdoable · Jan 12, 2022

That flap hanging down is the secondary mirror that directs the central portion of light down to the AF module in the floor of the mirror box. It's not properly folding up with the main mirror, so either the main mirror is not raising completely, or the linkage needs service.

Xiao · Jan 12, 2022

Thank you both very much. From what I can see, there is only a piece of tape attaching the small plate to the mirror. Feel like there is nothing mechanically nor electronically controlling the plate other than the tape. My guess is something is missing there. I am going to send it to a shop and see if they could have this figured out.

Again, thanks a lot for the help.
Xiao

Deleted member 88956 · Jan 13, 2022

So it is hanging down and when you try with finger to bring it up what happens?

AgX · Jan 13, 2022

You mean the flap with the accessory mirror just went out of contact with its (hidden) control lever.

Pentax 645N Dark Shadow on the Frames

Xiao

Sirius Glass

Xiao

Deleted member 88956

Xiao

Deleted member 88956

Deleted member 88956

itsdoable

Xiao

Deleted member 88956

AgX

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