Any Nikon gurus? Having an odd indexing issue.

[TheTrailTog]

I'm having an odd aperture indexing issue that I'm hoping someone might have the solution to. I just got a 28-45mm f/4.5 non-ai lens. The lens is in really nice condition, but I can't get it to index the aperture on my Nikkormat FT2. Sometimes it comes up as 1.4, other times as 2.8. I have no problems with any other lenses on this camera, including primes and zooms. My first thought is an issue with the lens. However, it works just fine on my F2 Photomic. I've tried several times with both cameras and it's the same every time, fine with the F2, but not the FT2. Any thoughts on what the issue could be?

 

[George Mann]

Nikkormats are pretty complicated beasts. Only a couple of gurus can service them. They get buggy as they age.

 

[TheTrailTog]

Funny thing is, this was just CLA'd last month. It indexes my 80-200mm f/4.5 non-ai fine. Just so bazaar that it is just the combo of this body and lens that are giving me an issue.

 

[George Mann]

My FT2 can never make up it's mind on how it is going to malfunction from day to day!

 

[cooltouch]

Perhaps this lens's aperture ring is set ever so slightly off such that the meter "fork" is also slightly out of alignment from where it should be? Any evidence of tampering there? Is the fork bent at all?

 

[anfenglin]

I've had the same issues on my FTN. The 50mm f2 indexes just fine, the 3.5 3,5cm I used to have would not index properly half of the time.
I've seen a repair manual once for the indexing mechanism and decided to leave it alone and shoot sunny 16.

 

[cooltouch]

I've seen a repair manual once for the indexing mechanism and decided to leave it alone and shoot sunny 16.

I removed the busted pantograph mechanism (that's what they call the indexing thingy) from my F2S's finder, hoping I could fix it and after hours of futzing around with it, gave up in bewilderment. I finally just bought another DP-2 prism finder for the camera. So now I have spares, I tell myself.

 

[TheTrailTog]

Perhaps this lens's aperture ring is set ever so slightly off such that the meter "fork" is also slightly out of alignment from where it should be? Any evidence of tampering there? Is the fork bent at all?

The lens is very clean. It doesn't appear to have ever been worked on. Nothing is bent, no scratches, nothing.

As an update, after fiddling with it a bit, I've gotten it to index correctly a few times now, though still not every time. Still baffled as to what the issue could be as I've never had a single issue with any other lens on this camera and this lens indexes just fine on my F2.

 

[bdial]

Seems like it must have something to do with the metering fork, since that makes the only connection to the mechanism in the camera for indexing. If the slot is closed a bit, perhaps due to a drop, or possibly the fork is slightly misaligned, the pin might not move freely.
One easy thing to try would be to "borrow" the fork from another lens and try it on this one.