35mm sprocket alignment standard (or lack thereof)

markjwyatt · Mar 19, 2021

Is there any standard for alignment of sprockets and images in 35mm cameras/film stocks? I see a lot of talk about sprocket styles, but how about any mechanical synchronization? I ask because I have a plastic 35mm strip film holder (looks like it come from a scanner) with sprocket protrusions. Sometimes I put a strip in and I can't get the sprockets synchronized with the full frame. I often lose part of an edge. If I try moving one sprocket left or right it just gets worse. I am thinking about trying to just grind the sprocket protrusions off so I can slide the film back and forth.

John Salim · Mar 19, 2021

Ideally the frameline should be 'dead centre' between perforations, but unfortunately there is no 'standard' frame alignment for 35mm stills cameras ( unlike motion picture ), so you're stuck with what you've got.
I know one or two cameras ( particular Nikkormat and Pentax models I believe ) will print the frameline through the perforations.

John S

markjwyatt · Mar 19, 2021

John Salim said:
Ideally the frameline should be 'dead centre' between perforations, but unfortunately there is no 'standard' frame alignment for 35mm stills cameras ( unlike motion picture ), so you're stuck with what you've got.
I know one or two cameras ( particular Nikkormat and Pentax models I believe ) will print the frameline through the perforations.

John S

That is definitely my experience. Thanks.

Makes me wonder why anyone created a 35mm negative strip holder that registers with sprockets...

Kino · Mar 19, 2021

Even with "Standards" for motion picture perforation spacing, those have changed throughout the history of film. Even within a particular standard, the frameline can shift due to shrinkage of the base, so our specially modified cement splicers have registration pins that can be moved back and forth with a micrometer-type lead screw to adjust the position the splice will occur.

It would take some effort, but you could modify your negative carrier (assuming this is what you speak of) to make your pins slide a bit back and forth to center whatever image in in the aperture.

Here's a picture of the splicers we use; Made in Canada!
http://www.canadianfilm.com/KL/Shrinkage-Full.03.html

gorbas · Mar 19, 2021

It's totally dependant on design of the camera. All my Leica M are dead centre, so you cut film thru solid part of perforation. My Nikon's and Pentax spotmatic are not not as precise as Leica but very close. My Bessa R forces me to cut negative right thru "hole" part of perforation. No fiddling with loading can change that position.

cmacd123 · Mar 19, 2021

in some but by no means all cameras , their is some leeway to adjust the sprocket position. My Canon eos cameras not only align the sprockets but measure from the start of the roll so accurately that the frame numbers are centered on each picture. others drift so much that some frame lines bump together while others are widely spaced on the same roll.

I agree that it would be nice if the frame line allowed cutting between frames without cutting through sprockets.

I have an old Veiwlux film stip projector which has a detent to advance one (Half) frame at a time, and it has a small framing knob on one side to align the frame on the first image. perhaps your holder has a similar adjustment placed out of the way?

ic-racer · Mar 20, 2021

Can you show a picture. I have never seen a negative holder with pins for sprocket holes. Even with movies between my 3 Bolex cameras, I need to make fine adjustments to 'framing' with the projector.

spl · Sep 9, 2021

My OM1 takes negatives that align perfectly with the negative transport tray, but as warned in the manual for the film scanner there may be non-standard cameras that misalign them and you should just crop the image. My OM10 unfortunately does this, though I doubt it's really non-standard, it's probably just not trying to follow the standard that the negative transport is inadvisably built to. Additionally and separately, the scanner cuts off the last 1mm of the negative which really messes up some compositions.

I fixed the sprocket misalignment and eased the inappropriate cropping of the bottom a bit like this: I used a suitable blade (Stanley/exacto/craft knife) and pushed it against each sprocket protrusion until it pops off. I then cut 8 small strips of thin light seal foam and placed it in opposite positions in the lid and base so it squeezes the negative into place when the lid is closed. Best to only do one or two frames, leave the remaining 4 free of foam so the negative can be positioned and handled easily: less is more. It takes slightly longer to load the negative but it fixes the alignment issues, and can help a bit with inappropriate cropping in the holder, because at least you can vertically centre it which works sometimes. It would be better if it overscanned, then you could do sprocket holes, but I suspect a medium format scanner may be required eventually.

Adrian Bacon · Sep 9, 2021

In my experience, there doesn't seem to be much standardization, even the 24x36mm frame size seems to be fairly nominal. I've seen film come through my shop that was supposedly "full frame" 35mm, but the camera only exposed a very conservative area and left a huge amount of rebate surrounding the exposed frame area. I've also seen film come through where the exposed frame area extended all the way to the sprocket holes on the top and bottom of the frame and left almost no rebate between frames. I've also seen film come through where the position of the frame floated up or down towards the sprockets instead of being centered between the sprockets, and yes, more often than not, alignment of the sprockets in the horizontal direction is all over the place. It is what it is.

Wallendo · Sep 9, 2021

My experience is that electronic cameras which load automatically align the film fairly precisely and the frames line up with the numbers in the rebates well. My older all-mechanical cameras tend to line up the gaps between sprocket holes, but don't always align with the rebate numbers. My oldest cameras seem not to be particularly consistent as for spacing between images.

Kino · Sep 9, 2021

The great thing about standards is that there are so many of them to choose from...

MattKing · Sep 9, 2021

Just think what it must have been like operating those Kodachrome semi-automatic slide mounting machines .....

Bill Burk · Sep 9, 2021

Kodak 35 and Retina drive the shutter cocking mechanism from the sprockets. These wander around if they don’t outright tear the film between sprocket holes

koraks · Sep 11, 2021

Wallendo said:
My oldest cameras seem not to be particularly consistent as for spacing between images.

I found (rather obviously/logically) that being *very* consistent in how you advance the film helps with this. E.g. if you take your typical lever-operated film advance/shutter cocking camera and you *always* push the lever in one go right up to its stop, you get pretty consistent frame spacing. If you sometimes stop a tiny bit shy from the hard stop at a point where the mechanism already will release (i.e. the shutter has been cocked, frame has been advanced), you'll get variable frame spacings.

35mm sprocket alignment standard (or lack thereof)

markjwyatt

John Salim

markjwyatt

Kino

gorbas

cmacd123

ic-racer

spl

Adrian Bacon

Wallendo

Kino

MattKing

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Bill Burk

koraks

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35mm sprocket alignment standard (or lack thereof)

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