Cutting very thin negatives accurately

I've had my 35mm negatives stored in full strips in the canisters the lab I use ships them back in for years now, and I'm working on cutting and sleeving them for more archival storage and easier scanning. I have more than a few rolls of very thin film from night shoots, concerts, etc. where I cannot tell by naked eye where each frame ends and another starts. I know there's detail in the frame because the scans show it, but looking through the 50mm lens I'm using as a loupe over/under bright light and a white paper background I cannot for the life of me see where the frames separate.

 

I want to avoid storing these strips rolled up because I know that eventually they won't want to unroll, and be harder to scan. Is there a decent way better than guesstimation to cut these strips accurately?

Can you find just one line where the frames separate? If you can find one then all the lines will correspond equally to that one. What you can do is note on the film how many sprockets to the right or left of the frame number indicator the separation line is. For example the separation line might be 2 and a half sprockets to the right of the number 3 (indicated on the bottom of the film strip). Every separation line will be 2 and a half sprockets to the right of its corresponding number on the bottom of the film strip.

 

Or if you can find one separation line, you can place another, well-exposed strip of film on top or below the thin strip of film to indicate where the lines would be.

 

If you can't find any lines you could make one print at 35mm negative size from one of the scans and use something in the image to line it up with the negative image, thus revealing where the edge of the image would be. Then use one of the methods above for the rest of the strip of film.

Flip the film over and look at the emulsion side. You might be able to see the frame outlines & could cut from that point. Aloha, Bill

Use the sprocket holes as a guide.

 

There are exactly 8 sprocket holes per frame, including the inter-frame spacing. So once you've got the spacing for one frame correct, then cutting a thin frame at the same point WRT the 8th (or multiple of) sprocket hole will be correct.

 

The perforation spacing or pitch is exactly 4.75mm, giving an 8 'perf' spacing of 38mm. Most cameras pull this frame spacing very accurately, but some are a bit 'rattly' and may not be absolutely consistent between frames.

 

Scroll down to the 'Characteristics' section of this link.

Examine some frames of developed film that came from the camera in question. We are talking about strips with visible images and frame lines. Using a millimeter rule, check several such strips to find the average distance, center-to-center, and frame line to frame line. This is important because cameras very as to the distance advanced between frames. This distant can also very, start of roll to end of roll.

 

High speed film cutting machines in photofinishing labs use fuzzy logic along with frame detection to make an educated guess. You can do better.

 

Keep in mind, if the frame line is so indistinct that you can’t see it, it likely won’t matter provide the cut is not shorter than 1 frame length.

 

Best of luck and Happy New Year!

Yes, I have seen this with things like ice shows lit by followspots.

 

If you look through the whole roll, you might find adjacent frames where the lit spot in one is close to one edge, and in the next, close to the other edge.

 

The Print-File pages that I use are very close to five frames wide.

 

If you use a similar system, you could put the strip in, move it around such that five (or a different number) fit just right.

 

Easier than counting sprockets, is the relative position (in sprocket holes) to the numbers on the film.

 

But yes, as above, if you find places an appropriate spacing apart to cut, and don't cut through any visible image,

it should be close enough.

 

It is amazing, sometimes though, how light an image can be and still print, especially with color negatives.

 

I did have a roll, without this problem, from a real lab, with a few of the frames cut right down the middle.

I am not sure how they did it, but when I asked for copy negatives from the prints, they made them for free.

Examine some frames of developed film that came from the camera in question. We are talking about strips with visible images and frame lines. Using a millimeter rule, check several such strips to find the average distance, center-to-center, and frame line to frame line. This is important because cameras very as to the distance advanced between frames. This distant can also very, start of roll to end of roll.

 

(snip)

 

Cameras that I know, are pretty consistent, even between rolls, that the cutting spot comes between sprocket holes, and reliably eight holes.

 

But yes, there have been many different cameras, I suspect some better and some worse.

 

Then there are cameras like the Mercury II, with unusual frame width. I think close to five sprocket holes, but not exactly.

@ glen_h --- I spent 55 years in the photofinishing business. I designed giant photo labs (20,000 rolls developed / printed per day 7 of them) and tiny one-hour labs. I also designed a lot of the equipment used in this industry. Automatic cutting of negatives is a difficult task because of the high variability frame to frame and because a miscut negative is often a tragedy. Lot's of grief designing and making and using these high-speed negative cutters.

At some point, possibly after that, I started asking for negatives returned uncut.

 

One reason is that I had PrintFile pages that hold five frame strips, and wanted to use all

five, instead of the four they usually cut them into. I think everyone I ever asked was

good at returning them uncut.

 

I now have a Pakon F135, a scanner that scans whole uncut rolls, so now I ask for

uncut for that reason. Then, when I have scanned enough, cut them for the file pages.

 

I think the one that miscut mine was Qualex, which I usually used at the time.

I started asking for negatives returned uncut.

 

Yes, this is the best solution combined with the methods for identifying the borders suggested above.

 

Of course, the OP's negatives are uncut, as I understand it.

I'm amazed at the sheer volume of great help here, thank you all!

 

Ended up buying a proper light box so I could see better, getting some new xacto blades, using the sprocket measuring from frames I could find along with matching against strips from other rolls through the same cameras and being willing to cut less than the full 5 frame strips my files use I was able to get through a handful of problematic rolls. My FTN and K1000 have super variable distances between frames which made life difficult but I got there in the end. Or at least I think I have, we'll see what happens when I go back to scan them...

 

Thanks again!

Bit late to the party (couldn't find the kitchen). Philatelic suppliers sell small guillotines for cutting 'Hawid'-type mounts extremely accurately and squarely, and have mm measurements on the actual base, which may help.

Philatelic suppliers sell small guillotines for cutting 'Hawid'-type mounts extremely accurately and squarely

 

- Well, that gets my stamp of approval.