Zorki (4k): Grease on shutter spindle?

[Grytpype]

When I CLA'd my 4k I found quite a bit of grease inside the upper drum on the shutter spindle - the general area shown at the left in the first picture in this Fedka page - some round the spindle where the 2nd curtain drum turns. I thought it might cause some drag between the curtain drums, and I cleaned it off as thoroughly as I could before oiling.

I've never been able to get this shutter to expose evenly across the frame at the faster speeds, and I'm wondering if the spindle was actually supposed to be greased. This might tend to smooth out differences between the curtain speeds across the frame and would stabilise the gap between them. In fact, there doesn't seem to be any other reason for the grease having been there in the first place.

How independent should the curtains be in a Zorki?

Steve.

 

[Nomad Z]

Assuming it works the same as the earlier shutters (Zorki/FED 1), the tension of each is set at the sprung roller/drum things at the other side. As I understand it, there should be no friction-type drag at the drum and spindle to control the relative speeds. That said, the springs are fairly strong, and I wouldn't have thought that a light grease would cause much drag. If you consider that the pull of the springs is on the outside diameter of the drum and the reels that the ribbons go around, and that the greased parts are within that diameter, then the force applied by the springs on the parts that 'drag' is multiplied. Maybe a really heavy, thick grease would have an effect, but I can't see light grease being a problem.

I don't know what the correct lubricant would be, but for stuff that has what I would call a gross movement, I would generally use grease. Light stuff, such as timing-critical bits powered by weak springs (like the rod with the wiggly bit at the top that engages with the shutter timing mech), tends to get oil.

 

[Grytpype]

I take your point about the diameter of the drums. Also of course, with too much drag, the intermediate speeds, like 1/60 and 1/30 could be affected by the 2nd curtain closing slowly after the 1st curtain had finished.

I certainly haven't found any evidence in searches that the spindle should be greased in Leica type shutters, but in spite of several attempts there's just no way of adjusting the tensions on this shutter to produce what I would call satisfactory results, and as I've said, I can't see why else the grease would have been there. It seems to me the shutter might work better if it were a bit more 'Kiev-like' - i.e. the curtains linked together, even only partially.

 

[Nomad Z]

In what way are the images uneven - which side is darker? And, is the change gradual or sudden?

 

[Valkir1987]

Both curtains should praktically run at the same speed. Other adjustments can result in uneven exposures. In Zorki's, the first curtain pulls the second forward if the first one is faster.
Leica's have both curtains running free and their adjustment is even more critical.

To check both curtains have the same speed, wind the shutter on a fast speed unfully and release it. The curtains should stay closed, when the shutter is not completely wound and released. Test the 1/1000 speed to check if the second curtain doesn't catch up with the first or darkens one half.

You can check the speeds either with a shutter tester, or with the B mode of a digital SLR camera.

 

[Grytpype]

I've attached pictures taken with a digital camera of a uniformly illuminated ground glass taped to the film-plane at 1/1000 and 1/250 sec (shot from the front of the Zorki). You can see it's brighter at the start of frame (left). Actually it doesn't look quite as bad as I remember, but what you see is as good as I can get by tension adjustments.

I'm interested in what you said, Valkir "In Zorki's, the first curtain pulls the second forward if the first one is faster". How does it do that, and how does it differ from the Leica shutter?

 

[wolves3012]

The two shutter curtains aren't meant to be linked, as far as I know, by putting grease or anything beyond some fine oil on the pivots they share. In an operational sense, there is no difference between the Leica and Zorki shutters either. Personally, I do not think there is any significant mechanical coupling between the two curtains. They share a common pivot at one end and the tapes pass over the rollers to provide slight coupling. This is only a personal opinion but I don't see how this couples them. Others do think it's significant. With one of these shutters on the bench, try holding the second curtain mechanism back when the first curtain is released and feel the (lack of) drag.

As for your Zorki, looking at the ground-glass shots above, there looks to be to be a distinct line where the exposure changes, not a gradual change. That suggests that it's not a case of one curtain catching the other up across the frame but it's an abrupt change such as capping. Which way around are those frames, are they as if looking at the film-gate from the back of the camera?

 

[Grytpype]

The digital shots are from the front of the camera, so the bright area is at the start of frame. I agree there is a fairly well defined bright area; also the faster the speed, the narrower the bright area.

 

[Valkir1987]

Dear Grytpype,

I'm sorry for giving inproper information, the curtains in the Zorki 4 run free uncoupled as well. (It is in fact only the case with some Zorki 1 and Fed 1 models.

The Zorki 4 also has a 'shutter break' which slows down the first curtain at the end of its travel. Its located as a 'wheel' beneath the main shutter drum, you can reach it by removing the same plate you need to remove to adjust the curtain tensions. Be carefull bending or adjusting it. I doubt it is involved in the shutter fault seen on the screen.
If a quick 'CLA' isnt sufficient, the shutter needs to be taken apart to clean and relubricate the moving parts.

With kind regards,


Valkir

 

[Grytpype]

Thanks, Valkir. Yes, I know the anti-bounce brake you mention, and I'm sure it isn't a problem. It actually wasn't a 'quick' CLA - more of a 'take-off-every-last-screw-and-widget-whether-you-need-to-or-not' CLA, which is what I tend to do the first time I do any particular type of camera!

There was one issue that was puzzling. The large baffle had on its back a couple of strips of velvet light-seal material. These were too wide for the indentations in the baffle where they were apparently supposed to fit, so they stood high and rubbed quite heavily on the 2nd curtain. I cut them narrower so that they fit better, but I still had to enlarge the fixing holes for the baffle before I could stop the strips rubbing on the curtain. Maybe this was a mistake. When I have the time, I'll maybe try moving the baffle back so the strips rub on the curtain again and see what effect this has.

Steve.