F3 shutter problem

I have an F3P that was a newspaper camera in a previous life, so it

has seen plenty of use (it wouldn't win any beauty contests, that's

for sure). I have narrowed a problem down to its shutter by testing

various lenses and comparing shots with those taken with another

body. The problem manifests itself in the photos - the right side of

the photos is darker than the left side. Its not uniform, but

there's no hard line either - on a 10cm x 15cm print it is most

noticeable in the last, say, 3cm. With the camera shutter's

horizontal travel, I'm guessing that the second curtain is not

travelling smoothly, maybe 'hesitating'. Does this sound right?

Yep, sounds like the second curtain is catching up with the first one during their travel time.

If I'm correct the curtains move from right to left during travel. Image is being projected upside down on film. Dark side is on right side of picture, so the fault happens at the end of the travel-time.

Your description seems to be that of "tapering". Normally, the two shutter curtains should travel at the same rate of speed, so that the gap between them remains constant, and so does your exposure across the frame. There is no physical relationship between the first and second curtains - they are adjusted independently. The gap between them is of course set by the timing mechanism, which is a quartz oscillator and electromagnet in the F3, and clockwork in earlier Nikons. If the second curtain actually travels faster than the first, then as the curtains move across the frame, the second curtain starts gaining on the first, and the gap becomes progressively narrower. You notice a gradient of decreasing exposure from one side of the frame to the other. I have film in my camera at the moment, but if the F3 curtains travel left to right when fired, you will have what you are describing. (At least I think so - the image is reversed right to left, but it's also upside down at the film gate. You flip the final print back to the correct orientation). If you will look at your shutter curtains when fired and tell me the correct direction of travel, I'd really appreciate it.<p>There is a simple way to tell if you're tapering. Shoot with a slow shutter speed that exposes the full frame for a considerable period of time, e.g. 1 second. Then adjust the exposure so that you have equivalent exposure with a shutter speed that uses a gap in the curtains, e.g. 1/250. You may need some slow films and a ND or polarizer filter to experiment with this. At any rate, the final slides (use slides, not print film for these experiments) should show no noticable difference in exposure between the two frames. If the 1 second exposure looks fine, but the 1/250 exposure shows your gradient of increasing darkness, then you need to get your shutter curtain travel adjusted.<p>As an aside, I try to avoid purchasing from PJs as they put their gear through tough conditions. I love purchasing from a camera collecting health professional who babies and fondles his gear - in other words, someone like me!

I'm not 100 percent sure, but I think the curtains travel from the right to the left when looking from the rear side of the camera.

If you advance the film (=cock shutter), the trolley on the right side of the camera is turned to roll the curtain on it, so when the camera is cocked, the second curtain is on the right trolley of the shutter mechanism and will go to the left when firing.

 

...but I'm not sure :-)

 

Regards, Raf

The other term I've read for uneven shutter curtain speed related exposure problems is shutter capping. The shutter curtains may be electronically timed, but they are spring driven and the tension has to be adjusted so they move at the right speed. The sure symptom of this is that it's worst at the camera's highest shutter speed and lessens at lower shutter speeds. On cameras that I've had this problem with it was only the 1 or 2 top speeds. You can either avoid those shutter speeds, or get the camera serviced.

Raf,<p>You may well be right. It's just that there is film in the camera now and I can't verify the direction of shutter travel. At 3AM local time when I wrote the post, I couldn't figure out the exact geometry (even now, I still can't). All of us seem to agree that it's due to unequal shutter curtain movement.

I too have and F3P and I can personally attest to hundreds of thousands of frames that

mine has taken, that said, it is tough. Don't worry too much, a good CLA would put this

right, I prefer Nikon for this but I'm sure others would do a good job as well, I've had very

good service for older Nikon gear at Authorized Photo Service. As for the old PJ gear, being

a former PJ myself, my gear got serviced on a regular basis, anytime anything needed

looking at it was full CLA on the papers tab, so much of the PJ stuff was better cared for

than the 'fondler' gear was. I bet once you get this shutter fixed it will last _years_.

Have fun.

Thanks all. I haven't resolved this yet, but I wanted to catch up.

 

RAF is correct with the direction of the shutter - when cocking, the curtains move left to right when looking directly at them with the back open.

 

Robert - I did as you suggested - did a roll with varying shutter speeds from v.slow to v.fast. Anyway, we'll see what turns up.