Contax II film transport issues

[Coldkennels]

I am having absolutely zero luck with getting a roll through my Contax II in one piece - maybe one of you guys can help me understand what's going on here.

On most rolls, I'm getting erratic spacing, with some frames literally touching the previous one, if not overlapping very slightly. Other frames will have double the usual gap between them and the previous one.

However, on more than on occasion, I've hit a point where the damn thing just jams up mid-roll; the shutter will cock and fire properly, but the film isn't moving at all, and I have to open the camera in a darkbag and reseat the film on the sprockets. Once the roll is developed, I find the sprockets have torn straight through the sprocket holes.

I tried removing and relubricating the rewind shaft in case it was sticking, and even picked up proper Contax cassettes to reduce drag on the film further, but no luck - took the damn thing to a gig over the weekend and hit the same jam again after about 10 shots.

Any suggestions? I bloody love the lenses I've got for this thing but the body is so irritating I'm starting to lose my patience with it!

 

[Sarcophilus Harrisii]

I am having absolutely zero luck with getting a roll through my Contax II in one piece - maybe one of you guys can help me understand what's going on here.

On most rolls, I'm getting erratic spacing, with some frames literally touching the previous one, if not overlapping very slightly. Other frames will have double the usual gap between them and the previous one.

However, on more than on occasion, I've hit a point where the damn thing just jams up mid-roll; the shutter will cock and fire properly, but the film isn't moving at all, and I have to open the camera in a darkbag and reseat the film on the sprockets. Once the roll is developed, I find the sprockets have torn straight through the sprocket holes.

I tried removing and relubricating the rewind shaft in case it was sticking, and even picked up proper Contax cassettes to reduce drag on the film further, but no luck - took the damn thing to a gig over the weekend and hit the same jam again after about 10 shots.

Any suggestions? I bloody love the lenses I've got for this thing but the body is so irritating I'm starting to lose my patience with it!

I would suspect a faulty clutch on the take up shaft. The majority of 35mm cameras including the Contax need both a film sprocket shaft and take up spool shaft which are pulling their weight. If the spool clutch has insufficient friction, the spool may either not rotate enough or even not rotate at all in some cases. If this happens the sprockets may chew through perforations because the film is not transporting at the same speed as the teeth move.

A clutch with too much friction can be equally problematic. As film is wrapped around a spool or drum during the course of shooting a roll, the effective diameter increases. This has the effect of increasing the length of film which would otherwise be drawn around it—hence the presence of a clutch, so that only a frame length of film is drawn. But, if the clutch does not slip enough, somewhere around 1/2 to 3/4 of the way through a 36 exposure roll things come to a head—the sprocket shaft rotates a fixed amount every single time film is advanced (obviously, the nominal amount to draw 37mm of film across the gate, +/– a small amount, actual film gate length is rarely precisely 36.00mm, and margin between frames varies). But, the increased diameter of the spool tries to draw more than that. With a defective clutch it will pull the perforations across the stationery sprocket teeth—shredding the perfs in the process.

There might be other complications—Eg a defective pressure plate might be discouraging the perforations from engaging with the sprocket teeth fully—but the things you have described would see me checking the clutch first if it was my camera.

As tolerances by and large will tend to grow with use and wear, not decrease, insufficient friction may be more likely. This could be a result of wear; or it might be inappropriate lubrication. Pre war Contaxes, in my experience tend to be oil hogs, the unique shutter design relies on eliminating mechanical friction if fast speeds are to be close to nominal, because Eg the 1/1250 time will see the take up springs being tensioned the least amount. Cleanliness and correct lubrication are essential if the shutter is to run well at the fast speeds, however lubricating the take up clutch of many designs will reduce the friction too much—it's one place in most mechanisms where some friction is not only desirable but essential to proper function (another is the ribbon buckles or clutches of a pre-war Contax, but that's another matter).

I'd tackle this in the first instance by cleaning the clutch and exercising the wind. If that does not improve matters adjustment or replacement may be needed.

My Contaxes certainly do not advance frames with the same unerring perfection of a modern electronic film advance. Occasionally adjacent frames will just touch. But generally the advance works well enough. Keeping perforations out of the film gate is usually more of a consideration with modern cassettes but this can mostly be achieved with adapted spacers to encourage proper alignment with the film rails.

 

[Sarcophilus Harrisii]

I should add that by substituting a flat plate of the correct dimensions of the pressure plate across the plate rails, it should be possible to run a scrap roll across the gate with the back off and observe the behaviour of the system in real time. A Contax makes this trickier than some cameras because of its removable take up spool. I'd be inclined to use cassette to cassette feed to try this, because you can keep a finger or thumb on a take up cassette body to hold it in the proper place. A Contax take up spool won't sit anywhere near its correct position with the back removed as it will float around its lower end or even fall off the take up fork. If you had a scrap back, you could cut an opening adjacent the take up chamber and make checking the clutch that much easier, but spare backs for a Contax II or III should probably be preserved. Perhaps a Kiev donor back would achieve the same purpose, but, Kievs are becoming somewhat collectible in their own right...

 

[Mr_Flibble]

A temporary work-around that *might* help, is taking up the slack on the film with the rewind knob before advancing the film. Keep your finger against the rewind knob as you advance to give it a little bit more resistance.

 

[Coldkennels]

There might be other complications—Eg a defective pressure plate might be discouraging the perforations from engaging with the sprocket teeth fully

This is something I've considered, in a roundabout way. There's definitely a bit more play in the fit of the back than I'd like - it's definitely not as tight as a couple of the Kievs I have lying around. Considering how easily the film jumps off the sprockets, if the back and pressure plate aren't holding the film in place properly, I imagine it'd lose its position and start causing problems that way.

I'd tackle this in the first instance by cleaning the clutch and exercising the wind. If that does not improve matters adjustment or replacement may be needed.

Where is the clutch? I assume it's in the shaft/assembly between wind-on knob and the "prongs" for the take-up spool?

A temporary work-around that *might* help, is taking up the slack on the film with the rewind knob before advancing the film. Keep your finger against the rewind knob as you advance to give it a little bit more resistance.

I've tried that, and it actually makes it worse. Once things start getting stuck, I found that actively creating slack by unrolling the film left in the cassette slightly sometimes allows things to get moving again. That's why I took out and relubricated the rewind shaft - I thought maybe there was too much friction at that end. No such luck, though.

 

[Dralowid]

If all else fails we have a very good Contax man in the UK. Ed Trzoska but maybe you know him already.

http://www.europhotoservices.co.uk/

Michael

 

[Sarcophilus Harrisii]

This is something I've considered, in a roundabout way. There's definitely a bit more play in the fit of the back than I'd like - it's definitely not as tight as a couple of the Kievs I have lying around. Considering how easily the film jumps off the sprockets, if the back and pressure plate aren't holding the film in place properly, I imagine it'd lose its position and start causing problems that way.



Where is the clutch? I assume it's in the shaft/assembly between wind-on knob and the "prongs" for the take-up spool?



I've tried that, and it actually makes it worse. Once things start getting stuck, I found that actively creating slack by unrolling the film left in the cassette slightly sometimes allows things to get moving again. That's why I took out and relubricated the rewind shaft - I thought maybe there was too much friction at that end. No such luck, though.

Correct. It's in the form of a sleeve with a light interference fit. If Eg a well-meaning but uninformed repairer has lubricated it (or over lubricated the mechanism generally) this can cause an otherwise serviceable clutch to malfunction.

Alternatively, as mentioned if worn badly enough it might have excess clearance = insufficient friction to do its job.

I haven't ever noticed this with a Contax rangefinder to date, but I have had to adjust a Leica screw mount take up spool (unlike the Contax, the degree of tightness of the fit of the Leitz spool around the take up spool shaft, itself, constitutes the clutch). How did I know this? My friend's otherwise flawless IIIf (it wasn't flawless when he got it, but was, after I stripped and serviced it) would fail to load and advance a film correctly. Easily spotted, because the rewind knob would refuse to rotate during film advance. The Leica take up spool should have a defined amount of slip as specified in the service manual—due to wear excess clearance meant the shaft could spin freely without rotating the spool at all. I had to profile the spool friction tabs to restore correct fit, at which point, the advance functioned perfectly.

If as you've said, dragging a finger along the rewind knob as you wind makes matters worse, this tends to support the possibility of insufficient drive going to the take up spool, (Ie. Insufficient friction) although you should, indeed, ensure the pressure plate applies adequate force to its rails, of course.

 

[Sarcophilus Harrisii]

This is something I've considered, in a roundabout way. There's definitely a bit more play in the fit of the back than I'd like - it's definitely not as tight as a couple of the Kievs I have lying around. Considering how easily the film jumps off the sprockets, if the back and pressure plate aren't holding the film in place properly, I imagine it'd lose its position and start causing problems that way.



Where is the clutch? I assume it's in the shaft/assembly between wind-on knob and the "prongs" for the take-up spool?



I've tried that, and it actually makes it worse. Once things start getting stuck, I found that actively creating slack by unrolling the film left in the cassette slightly sometimes allows things to get moving again. That's why I took out and relubricated the rewind shaft - I thought maybe there was too much friction at that end. No such luck, though.

OK—substitution is an effective method of fault isolation. Assuming your Kiev backs fit your Contax correctly—certainly, a Kiev II back ought to, but I'm not intimately acquainted enough with all the Kiev rangefinders to speak for later models—then, temporarily fit one to the Contax, and wind a test roll of 36 exposures through it a few times. If it advances readily you can be reasonably confident a replacement back or repairing the existing one if possible will see it right. As the Contax backs and bodies had matching serial numbers I'd personally prefer to re-profile the original if at all possible. That said...I am still leaning towards the friction clutch being the likely culprit.

 

[Grytpype]

My money's on the take-up clutch as Brett suggested above. Have you tried just turning the take-up dog by hand and checking it does not have too much friction? If this is too tight it will definitely tear the sprocket holes. It is easy to dismantle by removing the centre screw, and you will find some washers (brass and fibre) and a spring. These need greasing. It is often not so easy to get back together, because it is hard to get the flats on the spindle to engage with the flats on a special washer under the screw, but it can be done.

 

[Coldkennels]

Bit of an update: finally finished the latest roll of film with no jamming after the initial failure (which was 9 shots in). Playing around with the camera back removed and my thumb acting as a makeshift pressure plate on the film rails showed that the camera would wind on properly until a certain point when the take-up spool would stop turning and the film would jump free of the sprockets.

I had a look under the take-up fork, and there were no washers between the fork and body; I stole the two I found under the fork in a Kiev 4, and at least in testing, the camera seems to be pushing film through without issue now. God only knows what will happen when I actually shoot with it, though.

However, developing the roll showed a new problem:



Yep, a nice big light leak. Looks like the back isn't meeting up with the top of the camera properly, so I spent this evening cutting light sealing foam to size to create new seals. I don't think I've ever had to work so hard just to get a camera performing half-decently before!

Incidentally, I noticed while scavenging from the Kiev that the Soviets increased the size of the pressure plate in the back considerably. The Contax's pressure plate only covers the film gate; the Kiev 4's pressure plate runs right up to the sprockets. I guess the Soviets must have spotted this problem at some point and made what seems like a pretty obvious "fix". Unfortunately the backs aren't interchangeable due to the difference in the tripod mount (the Kiev's is on the body shell and goes through the back; the Contax's is built into the bottom plate of the back), or I'd just swap them over and be done with it.

 

[Shafovaloff1]

Just got this book in from Odessa by Maisenberg hoping it would provide more complete diagrams and instructions for tuning up the shutter on a Contax II. The author included a diagram of the take-up spool fork and order for parts assembly.....a complex machine it is!