Help me diagnose this issue with my Nikon FM

Hi All,

This is my first post so hello! I recently shot a roll with my newly acquired Nikon FM and a few of the shots had this black bar. I had the film developed and scanned at a local lab that I frequent for my film needs. I'm wondering if you can help me diagnose what the issue here is--this black band is only visible on a few of the frames from this roll. Any ideas?

Thanks!

Shutter fading. The traveling slit is not staying open at the highest shutter speeds. I bet those pictures were all taken at 1/1000. Time for clean/lube/adjust.

You can dry fire with the back open and observe this. Remove lens, open back, hold to light, take pictures at different shutter speeds.

Shutter fading. The traveling slit is not staying open at the highest shutter speeds. I bet those pictures were all taken at 1/1000. Time for clean/lube/adjust.

 

You can dry fire with the back open and observe this. Remove lens, open back, hold to light, take pictures at different shutter speeds.

Thanks, John. This is the second roll of film I've shot with this camera and the first time I encountered this issue. The first roll turned out perfect or so I thought until I checked the images and saw one that had the same issue.

Between the two rolls, I tried to remove one old stuck screw from the bottom plate and ended up popping the head of it off. So I drilled down that screw hole and fit a slightly larger one in.

My immediate reaction to this black band was the drilling messed something up inside. I'm sort of glad now that this problem existed before opening the bottom plate.

You are right--if I remember correctly, all of the photos with this issue were taken at 1/1000 shutter speed. Do you happen to know off the top of your head how expensive of a job this will be or whether it might be better to invest money in another Nikon FM?

Easier is to not use the top shutter speed. Though that is harder with higher speed films.

Some use will soften up some lubricants which might have solidified with age.

But with a CLA, you should have many years of use left.

It could also be due to the mirror not raising fully. I think that's more likely than the shutter jamming or its blades not opening until 1/3rd through the travel.

You have to remember that the image on film is projected upside-down. So the unexposed part is at the top of the (horizontal) frame, and that's where the shutter starts its travel, and where a sticky mirror would obscure the image.

A shutter fault would be more likely to show shading at the end of its travel - at the top of the image.

I am not sure about the shutter top/bottom reasoning, but I think the blurriness of the black region also indicates

that it is more likely the mirror. Shutter blades would have a sharper edge.

I still have the FM that I bought 40 years ago. (I believe May 1979 is right.)

The shutter does act funny, but I can't explain what it does.

I think sometimes the mirror doesn't go back down until I wind the film, or maybe

not even then. (It was some years ago when I tried it last.) And it is worse at

higher shutter speeds, so I try not to use those. (Or maybe low speeds, I might

have forgotten by now.)

Used FM are pretty easy to find, though might also have similar, or different,

problems.

I am not sure about the shutter top/bottom reasoning....

A dark area indicates that no light is getting to the film. The shutter starts its travel at the physical top of the frame; bottom of the image. Therefore - if the issue is with the shutter - the shutter curtains would have to stay closed for the first part of their travel and then unstick for the last 2/3rds, and that's typically not how shutters fail.

Premature capping of the blinds usually happens at the end of travel when the trailing blind catches up with the leading one. Whereas blinds that start off being stuck together tend to stay that way throughout their travel.

My first suspect would be a stuck or sluggish mirror, or a mirror that's bouncing back down during the exposure.

Whether that makes the repair any easier, I really don't know.

The shutter starts its travel at the physical top of the frame

I believe the shutter in the Nikon FM travels upward. I no longer own one so I can't check.

I believe the shutter in the Nikon FM travels upward...

I just checked my FM and the shutter does start moving up from the bottom.

(snip)

 

Therefore - if the issue is with the shutter - the shutter curtains would have to stay closed for the first part of their travel and then unstick for the last 2/3rds, and that's typically not how shutters fail.

 

Premature capping of the blinds usually happens at the end of travel when the trailing blind catches up with the leading one. Whereas blinds that start off being stuck together tend to stay that way throughout their travel.

I suppose not usual, but still possible.

I have a TLR which sometimes works right, and other times the shutter goes at the fastest

speed (1/300) no matter the setting. As far as I know, it is more usual for a shutter to

go slower than the setting, but this one goes faster.

Works well on sunny days, though.

I have a TLR which sometimes works right, and other times the shutter goes at the fastest

speed (1/300) no matter the setting. As far as I know, it is more usual for a shutter to

go slower than the setting, but this one goes faster.

A TLR will have a leaf shutter - totally different from the metal focal-plane shutter that's fitted to a Nikon FM.

Despite the direction of shutter travel, the shutter is positioned close to the film plane (hence the name "Focal Plane Shutter") and shutter problems result in a sharper edged image problem.

This isn't a shutter, the mirror is the most likely culprit.

Just dragged my FM out of retirement, and the shutter does indeed run from bottom to top. Could've sworn it ran the other way, like modern Nikons... I've obviously reached the age when the mind plays tricks. Hey ho!

I still think it's more likely to be the mirror, but there's a fairly easy test. Open the back of the camera, take off the lens and simply look through the shutter as it's fired at a variety of speeds. If you can see the back of the mirror moving up, or down, at any point, then there's your problem. OTOH, if the shutter closes up at around 2/3rds of its run, then that's also nailed the cause.

You need a bright and constant source of light for the above test; the sky for example. Artificial lighting might strobe (flicker) and give a false impression of banding.

A TLR will have a leaf shutter - totally different from the metal focal-plane shutter that's fitted to a Nikon FM.

This is true, but I think the idea, that what is common and obvious isn't always what happens, is still there.

Drying oils and other aging tends to slow things down, but sometimes speeds them up.