Odd: Nikkormat shutter erratic only when back is open.

[Theo Sulphate]

This problem makes no sense to me.

So, I've been making photos with my Nikkormat FT2 quite a bit and I'm using the full range of its capabilities: fast and slow speeds, self timer, etc.

When changing film, I often trip the shutter with the back open. Yesterday, I noticed that at 1/8sec down to 1 sec, the shutter would be erratic and stay open for several seconds. However, when I closed the back, all was good. Timing was perfect. Opening the back again, it was a little better, but still some hesitation in the gear train. Close the back and all is ok.

It doesn't make sense. The only thing closing the back does is allow the frame counter to advance.

 

[shutterfinger]

On my F4s the instruction manual says NOT to operate the shutter with the back open as it may damage the shutter. The vacuum/air volume within the body with the back closed is figured into the shutter timing by design.
Now on your camera which is much older it may have not been factored in but it may still have an effect on the shutter.

 

[Theo Sulphate]

Yes, my F4s manual says the shutter won't operate with the back open ...and I wouldn't be tempted to defeat that interlock. However, on any pre-1990 camera, I'm sure I and many camera repair techs have tripped the shutter with the back open as a way to test shutter speeds, capping, and the aperture closing down all the way at the fastest shutter speed.

As for why the slow speeds on my Nikkormat are erratic with the back open, that's a mystery. It makes the kind of sound you hear when the gear train needs a CLA: erratic hesitation.

 

[E. von Hoegh]

With the back open, push in the release tab for the film counter and trip the shutter a few times.

 

[Theo Sulphate]

Well, I have film in it now, so...

But I'm sure pressing the tab would fool it into thinking the back was closed and the shutter would be fine. Yet, my question is: why? I don't understand how the film counter engagement could have anything to do with shutter timing.

 

[Sirius Glass]

I recommend that one take photographs with the camera backs closed. YMMV

 

[darkroommike]

I recommend that one take photographs with the camera backs closed. YMMV

+1 and I'll add that I used to have a car that ran perfectly, but only when it was in the mechanic's shop with the hood up, sort of the opposite of your problem.

 

[BrianShaw]

Your camera is haunted. That’s a gremlin tricking you. That behavior is both unexplainable and unnatural.

 

[Sirius Glass]

+1 and I'll add that I used to have a car that ran perfectly, but only when it was in the mechanic's shop with the hood up, sort of the opposite of your problem.

I find it hard to drive a car with the hood up.

 

[Theo Sulphate]

I find it hard to drive a car with the hood up.

In bad weather it's normal to drive with the hood up. If you're being silly, you can drive with the boot up, but the bonnet must be down.

In good weather, you fold the hood down.


Anyway, the only thing I can think of is that when the frame counter is engaged, there is additional indirect resistance in the gear train.

 

[blockend]

Given the data, the only conclusion is the pressure plate is pressing on one of the shutter rollers or the back is pressing on the timing mechanism. This is most unlikely unless the camera has taken a big hit, but theoretically possible. The alternatives are you or a technician open it up and have a look inside, or you stop worrying if the shots come out properly exposed.

I have a few Nikkormats and in common with many old mechanical cameras, slow speeds can be sluggish or inconsistent. The good news is regular use generally frees things up. My experience is Nikkormats rarely succumb to the kind of ailments that would kill lesser cameras, and fifteen minutes spent working through the operations, especially shutter speeds, gives you a functioning camera. This has even been true of some train wreck Niks that had no right to continue working. The only fault I've found is inconsistent frame spacing on one camera, but as none of them threaten to overlap I live with it and regular use lessens the tendency anyway.

 

[E. von Hoegh]

Well, I have film in it now, so...

But I'm sure pressing the tab would fool it into thinking the back was closed and the shutter would be fine. Yet, my question is: why? I don't understand how the film counter engagement could have anything to do with shutter timing.

I don't understand either, but if with the tab depressed the shutter functions, you have a place to start.

 

[zanxion72]

I have the feeling that the shutter works erratically when pointing the camera downwards. Try it with and without the back closed. It seems like a time for a good cla.
The frame counter does not affect the shutter.

 

[E. von Hoegh]

I have the feeling that the shutter works erratically when pointing the camera downwards. Try it with and without the back closed. It seems like a time for a good cla.
The frame counter does not affect the shutter.

Except that in this case, absent further information, it seems that it may effect the shutter. Who knows what was done in this camera before the op came into posession?

 

[BradS]

Your camera is haunted. That’s a gremlin tricking you. That behavior is both unexplainable and unnatural.

Everybody's thinking it...GREMLINS....I'm glad you were brave enough to say it.

 

[E. von Hoegh]

Everybody's thinking it...GREMLINS....I'm glad you were brave enough to say it.

It isn't gremlins, it's demonically posessed and needs excorcism. Just hope it's one of the minor demons.

 

[Theo Sulphate]

From the last roll that was developed, exposure and frame spacing were perfect.

The camera was in great shape when I bought it; no dents or dings. I had it CLA'd by a personal friend and Nikon-certified guy whose been doing this for 30 years. Oddly, the only problem it had before the CLA was that the frame counter sometimes wouldn't advance.

The idea of pressure from the back being closed is interesting.

 

[BrianShaw]

When was that CLA done and why not return it for re-evaluation?

To me the symptoms (and some of the conjecture) makes no sense to me at all. I'd bet that "something" is wrong with the shutter and your only occasionally noticing it because it is either intermittent or your observations are fawlty.

 

[Theo Sulphate]

When was that CLA done and why not return it for re-evaluation?

To me the symptoms (and some of the conjecture) makes no sense to me at all. I'd bet that "something" is wrong with the shutter and your only occasionally noticing it because it is either intermittent or your observations are fawlty.

CLA was January, 2016. I have a photo project I'm using that camera for now, so there's film in it.

But, when changing film and with the back open, I could see the 1/8 to 1 sec speeds hanging up and I could easily hear the hesitation. With the back closed, the speeds are spot-on (based on timing the sound) and the sound of the gear-train is wonderfully smooth.

It'll go back for evaluation, but this has me perplexed. I hate problems like this, even though it doesn't affect the actual image.

 

[Chan Tran]

The frame counter doesn't make sense to me. When you open the back did you point the camera down or up? I have a Pentax S3 which would at times hesitate if I point it in different ways.

 

[shutterfinger]

There is a service manual for the FTn at http://arcticwolfs.net/ . The film advance and shutter winding begin on manual page 15. Its likely something in the gear train off causing extra drag on the shutter with the back open. Being it works properly with the back closed I would ask the friend/tech and take his word for it.

 

[BradS]

I have six(!) mechanical Nikkormats.
All of them more-or-less work fine. Some are cosmetically challenged.
None of them behaves as described in the OP.
The shutter behaves the same with the back open as it does with the back closed, with or without a lens mounted.

 

[Theo Sulphate]

FINAL UPDATE: for some reason, the problem has gone away.

This camera gets a fair bit of use.

I've checked the shutter with the back open numerous times and now the shutter times are well within spec.

I can't discount the possibility that some small foreign object had previously interfered with the slow speeds and may do so again in the future. However, I have always been very careful to ensure my camera interiors are clean.

If this or any other problem pops up again, I'll have it CLA'd. Until then, it's been doing great - especially with my 28/3.5 pre-AI Nikkor.