Bronica EC frame spacing issue

[Deleted member 88956]

After last street out with Bronica EC I came back with 3 rolls, all used in same film back, with serious frame spacing variance. I don't see it with other backs, so has to be the back (had never used it before). This is 6x6 back

Essentially, there is a larger gap after every third frame (makes cutting easier ), then a much larger one after frame 10 (this was same on all 3 rolls), and one roll just cranked to the end after frame 10, the other two completed to frame 12, with one barely clearing end of the film before it was over.

Films used: RPX 100, FP4+, Delta 400

Has anyone experienced same behavior? Any cure? I don't shoot it too often and have good backs without this problem, so just want to figure out what this is about. BTW, back itself is in perfect shape and only insert has some wear marks where it interlocks with back, but just paint wear.

 

[nostalgix]

I have the same spacings with one of my back on the EC-TL. It is the only one of three backs so far that works at the moment. Besides these gaps between some frames I have to release the shutter and crank frames until frame 16 or 17. Then the back tells the camera that the film is over and I can wind up until the end.
The other two backs are mostly producing double (or three-, four- or five-times) exposures and film is transported forward only sometimes. I have no idea what might cause all these issues, because without film inserted the backs seem to work all the same.
But I haven't figured out what two of those three pins and holes in the backs do for the communication of the back and the camera...

 

[itsdoable]

Bronica S/EC backs measure the film using 2 rubber rollers on either side of the film gate. When these rollers get dusty, or the rubber gets hard, or the oil in the mechanism gets thick, these rollers can slip, giving you gaps in the film spacing.

Check the rollers (on the insert) and the flats that they press against. Make sure there are clean, "rubbery", have no flat spots, and turn easily. The mechanism in the back that it gears to must also turn easily. Sticky mechanism is pretty easy to fix (CLA) but damaged rollers are a little harder since the parts are not available.

 

[nostalgix]

Bronica S/EC backs measure the film using 2 rubber rollers on either side of the film gate. When these rollers get dusty, or the rubber gets hard, or the oil in the mechanism gets thick, these rollers can slip, giving you gaps in the film spacing.

Thank you for the details. I noticed those rollers next to the flat front the film is running accross and was wondering what they are good for.

Check the rollers (on the insert) and the flats that they press against. Make sure there are clean, "rubbery", have no flat spots, and turn easily. The mechanism in the back that it gears to must also turn easily. Sticky mechanism is pretty easy to fix (CLA) but damaged rollers are a little harder since the parts are not available.

On all three backs the rubber rollers "feel" the same from what I can tell by just moving them around with my thumb. They look a bit white here and there but not crumbly or outworn in general.
But what I noticed now by comparing those three backs of mine: When turning the gear manually that attaches to the camera only one is turning without minimal force. That back is the only one that works without doing double exposures.
I am not sure how I can get nearer to the mechanics on the backs right side, but maybe a little drop of oil might work?

Just to be sure, while I am on the camera backs now, is there some fluid to use that might refresh those rubber rollers, too?

Best regards,
Arvid

 

[campy51]

Bronica S/EC backs measure the film using 2 rubber rollers on either side of the film gate. When these rollers get dusty, or the rubber gets hard, or the oil in the mechanism gets thick, these rollers can slip, giving you gaps in the film spacing.

Check the rollers (on the insert) and the flats that they press against. Make sure there are clean, "rubbery", have no flat spots, and turn easily. The mechanism in the back that it gears to must also turn easily. Sticky mechanism is pretty easy to fix (CLA) but damaged rollers are a little harder since the parts are not available.

Thanks for that info. If anyone is interested in cleaning those rollers I use a rubber rejuvenator for cleaning rubber rollers on copiers and printers, but NEVER use on plastic it will melt it. It's so good that if a copier still jams after using it , the rollers need to be replaced.

 

[itsdoable]

...I am not sure how I can get nearer to the mechanics on the backs right side, but maybe a little drop of oil might work?...

I would not recommend "dripping" oil in there, that method has a tendency to get the oil where you don't want it - like on the rollers. What you really want to do is remove the old thicken oil/grease, which requires dismantling. But sometimes a drop of oil in the right place will get things going for a while.

... If anyone is interested in cleaning those rollers I use a rubber rejuvenator for cleaning rubber rollers on copiers and printers, but NEVER use on plastic it will melt it. It's so good that if a copier still jams after using it , the rollers need to be replaced.

Go easy on the rejuvenator fluid, it is a solvent that partially melts the rubber to make it soft again (hence the warning about disolving plastic), and is not a proper plasticizer. "Rejuvinating" rubber roller will give you a year or 2 before they dry out, and you need to do it again, but because you are dissolving the roller, you can only do this a few times - good for prolonging things like copiers, where you have replacement parts. I would only use it if the roller material is truly hard and slippery and not gripping the film backing paper any more.

 

[nostalgix]

I would not recommend "dripping" oil in there, that method has a tendency to get the oil where you don't want it - like on the rollers. What you really want to do is remove the old thicken oil/grease, which requires dismantling. But sometimes a drop of oil in the right place will get things going for a while.

The rollers are on the insert. I have the feeling that those are working quite well on both film backs so far. Everything is moving quite smooth and even that little lever that is near the upper gear and does not allow the takeup-spool to move in the wrong direction is working and makes the little ticking noises when advancing the film. (This is broken on my one functional film back and the spool is rolling back and forth all the time when inserting a new film. )
What seems to be very sticky is the gear that connects to the gear on the camera. I already tried to apply some WD-40 but so far it does not seem to make any difference.

If there even were a way to test functions without any film to ruin everytime...

 

[MattKing]

If there even were a way to test functions without any film to ruin everytime...

Use a single sacrificial roll, and then re-spool it back on to the original spool each time.
You can use it over and over for quite some time - just be sure to mark it as such.

 

[nostalgix]

Use a single sacrificial roll, and then re-spool it back on to the original spool each time.
You can use it over and over for quite some time - just be sure to mark it as such.

Do you mean re-spool by hand backwards on the original role?
I tried to use the takeup-spool as the original spool and spool it to the other back again yesterday when I noticed that the film is not transported, but that failed. The film got loose from the paper moved too much to one side and got cut on one side.

 

[MattKing]

Do you mean re-spool by hand backwards on the original role?

Yes - back on to the original spool.
For clarity, this is with a roll that you have decided to sacrifice, so you can do this in the light.
For most cameras you can do this just with re-used backing paper.
All the discussion here about rubber rollers makes me think your camera is one that actually requires film in the package to check spacing issues.

 

[nostalgix]

Thank you for that idea. It's a bit tedious, but it works alright using the film insert from the back.

Another back came in the mail today. I was hoping for a working one, but it has almost the same issues like most of the other ones. Now I get the feeling it might be the EC-TL itself. (There is also one film back that works without all the double exposures but shoots on until frame 17 instead)
I noticed that the counter only increases when I hear the ticking noises that little break makes that keeps the takeup spool from rolling in the wrong direction. Side-note: The only working back does not have this break anymore. Has been broken since I have the camera.
Now I checked again what happens when shooting and the there are a few pins reaching from the camera into the back. And it seems that one or maybe two pins shoot out into the film back when the shutter is triggered.
Is there a chance that one pin pushes that thing below the one in the back that is moved out of the way when switched to double exposures and that does not happen every time?



I really would like to understand how this all works. I don't know if I would be able to fix it, but at the moment I don't know what might make sense. Maybe something is just a bit bend, but I don't see too much difference between all my film backs.

 

[itsdoable]

It sounds like you need to have the camera and film back CLA'ed, something is not right. Extra spacing between frames is usually because the roller mechanism is not working right. Double (or treble) exposures means the film is not moving, so the drive clutch, double exposure lever, etc... is malfunctioning. All the film positioning and indexing is done in the back, the interlocks just tell the camera whether the back is ready or not.

 

[nostalgix]

Thank you for the reply. To me it seems that it is the lever telling if the back is ready for exposure or the detector on the camera. I can't check that at the moment because I gave all this to a camera repair last week. But I as far as I can remember these to metal parts at the detector on my EC-TL were not at the same height.