Nikon F / F2 - Prism locking problems

[sanmich]

Hi all

I have had serious problems with the locking of prisms on my F and F2.
I have solved most of them, but my DE-1 still refuses to lock on my F, and does on my F2 only when the screen is off. It's the two rear pins that don't lock. It seems that the prism is at fault since my DW1 is locking fine.
I have tried playing with the pins orientation, and with the camera hooks position (bending them slightly), with no results.

I wonder if someone here would know a solution, or what is likely to be the cause of the problem...😕

Thanks!

 

[sevo]

Somebody in repair lost or misplaced the washers that determine the spacing and alignment of the prism cover. These should be inserted between the main prism assembly and cover. But as the previous position and number of the washer is invisible and they often seem to drop right out of nowhere when the prism is taken apart, misplacing them at the screw head rather than in between where they belong is a pretty common amateur repair flaw.

 

[sanmich]

Somebody in repair lost or misplaced the washers that determine the spacing and alignment of the prism cover. These should be inserted between the main prism assembly and cover. But as the previous position and number of the washer is invisible and they often seem to drop right out of nowhere when the prism is taken apart, misplacing them at the screw head rather than in between where they belong is a pretty common amateur repair flaw.

Thanks!
sounds about right..
I have cleaned this prism. I don't recall any spacer falling down, but it was a while ago...
Also, I see the cover clearly touching the camera.
I guess the way to check this is to remove the cover, and try to insert the prism.
But then what?
Where exactly should I place spacers, and how can I determine their thickness?

 

[sevo]

Where exactly should I place spacers, and how can I determine their thickness?

On the FTn head, there are four (longer) screws underneath the prism that hold the finder top ("body", in Nikon terms, not the outer sheet metal cover - that is attached from top) to the bottom ("prism box"). Two at the rear to each side of the eyepiece, two at the front somewhat hidden behind the latch pins.

The washers belong on these screws, right between the top and bottom half of the prism - use a bit of grease to tack them to the screw holes in the top half, and cautiously insert the bottom, with screws already in place, or they'll slip into the finder.

On one of my finders they used what looks like brass spacers of (IIRC) approximately 1/4mm strength, the other had considerably thinner steel ones - so either the strength is not critical, or they make up for casting variations and you'll have to find out the right strength for yours (unless you merely misplaced them on some other screws and can recover them).

I guess the DP-1 construction is about the same, but I've never had to disassemble mine.

 

[sanmich]

I understand.
I'll open the finder and try to add some space between the bottom and the top part on which the shell is attached.

Thanks very much Sevo!

 

[sanmich]

Sevo

It worked!
all needed was to put some distance between the cover and the base (same principle as yours but simpler, in the DA-1)
I found one tiny spacer, and created space in the rest of the four holes with a tiny bit of epoxy.
It works like a charm!
Thanks a lot!! 🙂