Leica IIIf (BD) curtain operation

[qqphotos]

So I came across a relatively inexpensive and cosmetically excellent IIIf BD which the seller claimed had been CLA'd and had the curtains replaced, and had all accurate speeds.


News flash: it doesn't.


IIIf BD shutter at 1/1000



Except at low speeds, frames start out black on the left and overexposed on the right. On high speed video you can see it doesn't even open for the first 1/8th or so of the frame, and then the gap widens increasingly across the frame. Increasing tension (by a lot, like 1/2 a turn of the gear) on the closing curtain makes it catch up faster so the gap more uniform but doesn't change the late opening. Decreasing tension on the opening curtain makes it never open at all. Tightening both leaves it widening non-uniformly again. I didn't want to go further and apply excessive tension.


Does the lack of a gap at the beginning of travel even have anything to do with tension, or is this from wrong starting position on the drum or something? I will probably send this to DAG or YYe to get straightened out, but I wanted to use it as a bit of an educational experience first.

 

[Sarcophilus Harrisii]

So I came across a relatively inexpensive and cosmetically excellent IIIf BD which the seller claimed had been CLA'd and had the curtains replaced, and had all accurate speeds.


News flash: it doesn't.


IIIf BD shutter at 1/1000



Except at low speeds, frames start out black on the left and overexposed on the right. On high speed video you can see it doesn't even open for the first 1/8th or so of the frame, and then the gap widens increasingly across the frame. Increasing tension (by a lot, like 1/2 a turn of the gear) on the closing curtain makes it catch up faster so the gap more uniform but doesn't change the late opening. Decreasing tension on the opening curtain makes it never open at all. Tightening both leaves it widening non-uniformly again. I didn't want to go further and apply excessive tension.


Does the lack of a gap at the beginning of travel even have anything to do with tension, or is this from wrong starting position on the drum or something? I will probably send this to DAG or YYe to get straightened out, but I wanted to use it as a bit of an educational experience first.

The curtains look original. So I think it is unlikely they are not positioned correctly. The second curtain looks to be releasing too early or possibly the first curtain is dragging, initially. There are a few possible causes for this: Foreign objects (in a screw mount, that means film pieces) impeding the first curtain; dirty mechanism increasing friction; badly adjusted second curtain release or defective release latch spring; are a few things that come to mind.

Regardless of the seller's claims the camera had been serviced, there's no doubt the mechanism will have to be removed from the body shell for further investigation. If I was working on it, I would start from scratch. And I don't much care for the condition of the bayonet securing screws, their slots have seen better days. Not a promising indication of the quality of any internal remedial work performed.

Note that the slit actually should widen a little as the curtains cross the gate (although obviously not to the extent visible in your video). The curtains accelerate as they run—their velocity is not constant. If the distance between the curtain edges was absolutely constant, exposure would decrease towards the rewind side of the gate in proportion to increasing speed. Rather than going into more detail about this here I'll just refer you to some previous remarks I've made in this thread.
Cheers,
Brett

 

[Chriscrawfordphoto]

If I were you, I would not have messed with the curtain adjustments; that camera is not in great condition and as Brett said, the curtains were not replaced. You should have just returned it.

DAG sells overhauled Leica screwmount cameras at prices often less than eBay sellers are charging for cameras that need serviced.

 

[qqphotos]

If I were you, I would not have messed with the curtain adjustments; that camera is not in great condition and as Brett said, the curtains were not replaced. You should have just returned it.

DAG sells overhauled Leica screwmount cameras at prices often less than eBay sellers are charging for cameras that need serviced.

By counting turns and photographing the original state, it isn't difficult to return everything to its original position. This isn't a valuable or rare camera, and I'm more interested in learning the basics of how they work and keeping them running than I am in just buying and returning until I get one that works adequately. Especially considering that even ones from reputable dealers seem to be in bad shape pretty often.

 

[qqphotos]

The curtains look original. So I think it is unlikely they are not positioned correctly. The second curtain looks to be releasing too early or possibly the first curtain is dragging, initially. There are a few possible causes for this: Foreign objects (in a screw mount, that means film pieces) impeding the first curtain; dirty mechanism increasing friction; badly adjusted second curtain release or defective release latch spring; are a few things that come to mind.

Regardless of the seller's claims the camera had been serviced, there's no doubt the mechanism will have to be removed from the body shell for further investigation. If I was working on it, I would start from scratch. And I don't much care for the condition of the bayonet securing screws, their slots have seen better days. Not a promising indication of the quality of any internal remedial work performed.

Note that the slit actually should widen a little as the curtains cross the gate (although obviously not to the extent visible in your video). The curtains accelerate as they run—their velocity is not constant. If the distance between the curtain edges was absolutely constant, exposure would decrease towards the rewind side of the gate in proportion to increasing speed. Rather than going into more detail about this here I'll just refer you to some previous remarks I've made in this thread.
Cheers,
Brett

This is really helpful, thanks.

 

[Chriscrawfordphoto]

By counting turns and photographing the original state, it isn't difficult to return everything to its original position. This isn't a valuable or rare camera, and I'm more interested in learning the basics of how they work and keeping them running than I am in just buying and returning until I get one that works adequately. Especially considering that even ones from reputable dealers seem to be in bad shape pretty often.

These cameras can be damaged by amateur repairmen. While not rare by any means, they're worth a few hundred bucks. I have no problem making camera dealers take back cameras they sell me that they fraudulently claim are in working order. I despise people who have no integrity; and unfortunately, I have come to hold camera dealers in far lower esteem than used car dealers these days.

 

[bluesun267]

These cameras can be damaged by amateur repairmen. While not rare by any means, they're worth a few hundred bucks. I have no problem making camera dealers take back cameras they sell me that they fraudulently claim are in working order. I despise people who have no integrity; and unfortunately, I have come to hold camera dealers in far lower esteem than used car dealers these days.

I'm with you on that one. It has become acceptable for many dealers to sell obviously faulty cameras at minty, 'just overhauled', or even higher, prices. But who is really to blame? While not excusing the dealers' dishonesty, I guess there must be no shortage of customers who will that pay those prices and not return them, otherwise we wouldn't be having this discussion.

There's more to a Leica's high speed performance than curtain tension. Depending on the model, there are other adjustments, not to mention the quality of the cleaning and lubrication. (All but the earliest ones have at least one more adjustment besides the curtain tension).

The last IIIg I bought was sold to me as overhauled, and I don't doubt that it was, but the repair person forgot the light seals--a not minor issue! This was from a very reputable dealer (they wouldn't tell me who did the overhaul however).