Intermittent M-A Film Advance Glitch

[logan2z]

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I purchased my M-A new about 4 years ago and the camera has been faultless.  Yesterday, however, I was out shooting and encountered a bit of a glitch with the film advance.  I know there have been reports in the past of new M-As with film advance problems, but mine has never missed a beat before and this problem seems a bit different than those reported by others.  Here's what happened:

I had the M-A around my neck and I was holding a second camera body in my hand.  I took a shot with the M-A and used the hand that was holding the second body to advance the film on the M-A.  It was a bit awkward to do with the other body in my hand, and I realized after releasing the film advance lever that I hadn't extended it far enough to cock the shutter.  So I pulled the lever again until I heard the shutter cock.  I took another shot and noticed that the rewind knob didn't turn as I advanced the film.  I fired the shutter again, then advanced the film again, and this time noticed that the rewind knob did turn.  So I figured that I had caused a glitch by not fully advancing the film on the last shot but the problem had corrected itself.  I shot a few more pictures and the rewind knob seemed to rotate as expected when I advanced the film so all seemed ok.  However, today I was out shooting again and noticed that the rewind knob didn't always turn (or barely turned) when I advanced the film.  Whenever I noticed that, I fired off a few frames and advanced the film after each shot, and the film would sometimes advance correctly, but not always.   

I had a possible theory that perhaps I had managed to introduce some slack into the film that required a few winds of the film advance to be taken up.  But once it started advancing correctly, I assumed it would continue to do so, but that wasn't always the case.  So I'm not sure exactly what is going on.  

Does anyone have a theory as to what might be causing this?

[giannis]

Before speculating what caused the "issue" it's better to check if there's an issue to begin with. Did you get overlapping frames? Irregular spacing? How do you know there's even anything wrong? The rewind knob doesn't always rotate with every single frame, the film can unwind a bit inside the canister while it's sitting, so it takes a couple frames to make the rewind knob start rotating again. If you shoot in succession, yes it will start rotating consistently, but if you let it sit at a frame it might not rotate much or at all in the next one. Especially if you're moving around and the camera gets bumped a bit.

[logan2z]

22 minutes ago, giannis said:

Before speculating what caused the "issue" it's better to check if there's an issue to begin with. Did you get overlapping frames? Irregular spacing? How do you know there's even anything wrong? The rewind knob doesn't always rotate with every single frame, the film can unwind a bit inside the canister while it's sitting, so it takes a couple frames to make the rewind knob start rotating again. If you shoot in succession, yes it will start rotating consistently, but if you let it sit at a frame it might not rotate much or at all in the next one. Especially if you're moving around and the camera gets bumped a bit.

Well, the roll is still in the camera so I guess I don't know for sure that something has gone wrong. I'm just going on my prior experience that every time I advance the film the rewind knob does turn.  This is the first time in four years that I have ever noticed this not happening, and it seemed awfully coincidental that it started happening immediately after I failed to fully advanced the film - also the first time I've ever done that in four years.  

I supposed it's conceivable that everything will be fine once I develop the roll, but was wondering (in advance 😉) if I'd done something that might have caused the film to not advance correctly.

Edited March 15, 2021 by logan2z

[giannis]

Well better wait and see, maybe it will turn out a non issue .

I've noticed in various cameras that the rewind knob can be intermittent sometimes, depending on the film and how long it has been sitting between advances. Sometimes, to be sure, I carefully turn the rewind knob until I feel some resistance, and then I advance, and sure enough the rewind knob turns in sync. Sometimes I've had to do that more than 2 times in the same roll, and I make sure it's very tight when loading, so it means that that film unsprung in the canister 3 times.

I'm not saying that it's impossible something went wrong, or the film didn't catch properly or something. But it might also be the case that you noticed it more because you paid more attention to it after the unsuccessful advance that made you worried something might be wrong. The proof is in the pudding though, and the negatives will reveal the mystery 

 

[ekindangen]

I had this problem with my M-A a few years back. Rewind knob didnt turn but I could advance the counter and release the shutter. True the film might not be taut at some point, but after advancing several times it eventually should be taut and turn the knob. The counter keeps advancing and it would go over 38!!! I sent it back to Leica for servicing but when it came back I think it still doing it a few times randomly. It's been working fine ever since though. The video of it is here 

.

[250swb]

Film does unwind in the cassette, and unwinds more as the space inside the cassette increases. If you shoot a few frames one after the other the film will usually stay tight, but putting the camera back in the bag or carrying it for a few minutes gives the film time to slacken. But it is only slack inside the cassette, not through the film gate. I think perhaps you have simply noticed something for the first time that's perfectly normal. 

[Frase]

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Just turn the rewind knob back to take the slack out before the nest shot, that will tell you if there is a problem.

Edited March 15, 2021 by Frase

[Graham (G4FUJ)]

That's what I usually do with my film cameras.

[logan2z]

6 hours ago, 250swb said:

Film does unwind in the cassette, and unwinds more as the space inside the cassette increases. If you shoot a few frames one after the other the film will usually stay tight, but putting the camera back in the bag or carrying it for a few minutes gives the film time to slacken. But it is only slack inside the cassette, not through the film gate. I think perhaps you have simply noticed something for the first time that's perfectly normal. 

I guess I'm not completely understanding what makes the rewind knob rotate when the advance lever is stroked. If the film is tight through the film gate and engaged in the sprockets near the 'tulip', why would the knob not turn when the film is advanced? 

Maybe I need to watch what's going on more closely the next time I have the camera open and I'm loading a roll of film. 

[a.noctilux]

Logan,

for simulation, it's easy to do.

Turn the rewind knob to the opposite of the arrow (after raising it of course) a couple of turns.

Then wind on the film, the two red dots must not move.

They (red dots of the knob) will move again after more than one wind-on, depending on the length of the film which was not tensing.

[250swb]

2 minutes ago, logan2z said:

I guess I'm not completely understanding what makes the rewind knob rotate when the advance lever is stroked. If the film is tight through the film gate and engaged in the sprockets near the 'tulip', why would the knob not turn when the film is advanced? 

 

The rewind knob is engaged with the spindle inside the film cassette, as the film is pulled through the camera the rewind knob rotates. But the film also acts like a spring and can unwind itself inside the cassette, so you have to pull more film through before it starts to rotate again.

Look at it this way, lay a length of string on the ground in a straight line, that is your tightly wound film and one end is the advance lever and one end the rewind knob. Pull the advance end of the string and the other end (representing the rewind knob) immediately moves. But now put a curve in the string, that represents the film that has unwound itself inside the cassette. Now when you pull on the end of the string (advancing the film) you have to pull the curve out before the other end, the rewind knob, moves. 

[logan2z]

1 hour ago, 250swb said:

The rewind knob is engaged with the spindle inside the film cassette, as the film is pulled through the camera the rewind knob rotates. But the film also acts like a spring and can unwind itself inside the cassette, so you have to pull more film through before it starts to rotate again.

Look at it this way, lay a length of string on the ground in a straight line, that is your tightly wound film and one end is the advance lever and one end the rewind knob. Pull the advance end of the string and the other end (representing the rewind knob) immediately moves. But now put a curve in the string, that represents the film that has unwound itself inside the cassette. Now when you pull on the end of the string (advancing the film) you have to pull the curve out before the other end, the rewind knob, moves. 

Sorry to sound dense, but I'm still unclear about how slack in the cassette can cause the rewind knob to fail to turn.  I understand that some slack within the cassette could form due to the spring-like nature of the film, but if the film is advancing and there is tension at the spindle end of the film, then I would expect the rewind knob to turn.  I can see how some slack at the spindle end (as @a.noctilux has described), could cause the rewind knob not to turn, however.   But I'm not sure how lack of tension at the spindle end could form in the middle of a roll of film after the roll has been properly loaded.

Apologies if I'm missing something obvious.

[250swb]

2 hours ago, logan2z said:

But I'm not sure how lack of tension at the spindle end could form in the middle of a roll of film after the roll has been properly loaded.

Simply accept it happens and don't try to build or invent anything vaguely mechanical. But try this, get a new roll of film and hold on tight to the leader, now wind it tight with the spindle, you see it winds up a bit more. Now let go of the spindle, you see it unwinds as the film springs back to its relaxed state. This is what is happening intermittently inside the cassette as you wind the film through the camera. The rewind shaft engaged with the spindle can only rewind the film, it isn't keeping tension on the spindle in the other direction as the film is wound through the camera.