how do slow speeds work?

[bukaj]

I just got a roll where I took a few shots at a 1/10th of a second, then that same frame a stop down at 1/4. To my surprised the shots at a 1/10th were slightly under exposed while the shots at 1/4 were quite a bit more under. I just got a CLA on this camera, but it is rather beat up, so I don't expect everything to work. Before I sent it out the slow speeds didn't work at all.

I remember reading that slow speeds can be set in between, so half way between 20 and 30 is a 25th of a second. The speeds on my iiic, are also listed 10, gap, 15, 20, 30, 4, 2, gap, 1, T. How does the mechanism work between a 30th and a 1/4? I'm guessing when I had it set at a 1/4 I was shooting closer to a 30th of a second. I've also noticed that 1 second binds, so it acts like T.

I'm guessing since this is still happening post CLA, I'll have to live with it, but as someone who generally tinkers a lot, the thought of taking it apart and trying to fix it has crossed my mind.

-jakub

 

[john neal]

The back of the slow speed knob has an inclined plane that pushes the slow speed rod into the camera to increase the "dwell" - at the top of the camera, a small lever interrupts the 2nd curtain latch and, depending on how far the rod has been pushed, you get different slow speeds, until at the furthest point, the lever completely locks the latch, and you have T. The IIIc has two planes, either side of the 1/30 setting. This is why intermediate points work - it's a gradual slope, not a step change.

It's possible that the knob is still wrongly adjusted, that the inclined plane is worn, or the rod is bent. I would bet first on the adjustment, then on wear. Have a look at Rick Oleson's website he has some drawings to show how to adjust the knob - no need to take anything apart. Of course, you could always return it to your repairer.

 

[bukaj]

thanks. I emailed Youxin who did my CLA, so I'll see if he remembers my camera. Maybe he can give me some insight.

Found the page, but don't I need something to measure the shutter speed to adjust it? If it's just that break point between 1/30 and a 1/4, I should be able to hear the difference. I'll play with it once I finish the roll in it. For now I'll test the slow speeds against my dslr for exposure.

 

[john neal]

If you set it so that T just works, then check the 1/8 setting - that will give you a good starting point

 

[bukaj]

Youxin told me my camera is simply in worn shape. It sounds like 1/2 is slow too. I took a bunch of shots comparing with my dslr, so I can see how the speeds are actually working when I get my next roll developed. Then I'll try adjusting it, but I think this might be more of a matter of learning how the speeds work and dealing with it.

 

[bukaj]

Just finished a roll so playing with the camera with no film. Anything slower than a 1/4s is inconsistent. Sometimes 1/4 and 1/2 work (or seem to work, just timing from observation) while other times the shutter is fast (my guess would be close to 1/30s). Sometimes 1 second works, other times it acts as if it were on T. One time 1/2s acted as if it were on T.

There also seems to be no pattern. I just fired 1/4 and it randomly works some times, and is too fast other times.

Also, is bulb effected by slow speeds? If I'm on bulb, and the slow dial is on T, I need to move the slow dial to close the shutter, but if it's on 1/30 for example, it'll close right when I let go of the shutter.

What could explain the inconsistencies? Could it just be parts (i'm guessing slow speeds operate using springs) worn?

-jakub

 

[charjohncarter]

Good luck, my Leica IIIf is inconsistent at 1/1000 and maybe 1/500 (post CLA, and shutter replacement), BUT I could live with that but they are inconsistent across the film plane (one side darker that the other).

 

[john neal]

bukaj,

Could be that there is dried out lube somewhere that it stopping correct function of the slow speed train, or there is a spring that is getting tired. The B / T thing is common and is not a combination that Leica expected anyone to use

John,

Sounds like capping - either tension in one of the curtains is wrong. or the release pawl is badly adjusted. Was it a home CLA? If not - send it back for adjustment.

 

[bukaj]

considering it just got CLA'd i'm guessing its a tired spring.

-jakub