scratches on 120 negative

[LucRoMar]

Good morning everyone,

Has anyone an idea how a negative can be scratched in a medium format back ?
I have a contax 645 and nearly all the pictures have 1 and sometimes 2 lines across them :


can it be the insert, I tougth the paper back would protect from scratches.

Should I try to clean it ? with alcool base solution ?

Thanks,

 

[Thomas Bertilsson]

Where are the scratches?

 

[250swb]

If the scratches are on every film over a period of time and in the same place I would suspect the camera back, perhaps the guide rollers aren't rotating or something like that. If they are just on one film, or on a batch processed at the same time I would suspect the lab.

Steve

 

[LucRoMar]

if you look at the first picture full screen, you can see the line acros the frame (vertical - between the knee and the boot and look above in the grass. ;-)

 

[LucRoMar]

250swb, wouln't the paper back of the 120 film protect from scratches wit hthe rollers ?

 

[LucRoMar]

and on the other photo it is horizontal (obviously) across the hands

 

[Thomas Bertilsson]

If the lines are that straight, where else could the film sustain damage like that? Have you tried different films with the same results?
Surely it can't be from processing as the reels would move around enough to cause scratches that are much less uniform.

 

[LucRoMar]

Indeed Thomas, as I'm new to all this I was wondering, I'll try and clean the back and insert before doing a new test roll

 

[Thomas Bertilsson]

Indeed Thomas, as I'm new to all this I was wondering, I'll try and clean the back and insert before doing a new test roll

If the negs are scanned as an entire strip, feeding the negs through the scanner might cause damage like that.
Depending on how the film was processed, when it's hung to dry some folks like to use a squeegee, which could also cause a reasonably straight scratch.
But I would be suspicious of the film back.

That gives you some places to look.

 

[AgX]

Sparing a film, lookin at it conspicuously (optical means) before loading and after winding through and unloading would hint at a manufacturer's fault, a fault at the camera or at fault at later stage. That should make you somewhat wiser.

 

[edcculus]

The line on the first image almost looks more like a problem with scanning. Where/how do you get the film processed and scanned?

 

[LucRoMar]

processed and scanned in a "pro" lab here in brussels (limelight http://limelightlab.com/).

I will inspect the back and insert tonight. I hope it is not serious as back for this are quite hard to find cheap.

 

[edcculus]

If you inspect the negatives, does a scratch show? If you line up the negatives on top of eachother, does it show in the same place? I downloaded the images and zoomed in closer, and it looks like it could certainly be a scratch.

Do you have B&W processing abilities at home? Id suggest running a roll of B&W film through and processing yourself. Take the lab processing and their scanning out of the equation. If you still can detect the scratches on your home processed B&W film, you can be sure its the back.

 

[pbromaghin]

Take a real close look at the negatives. If the scratch isn't there then it would be a scanner fault.

 

[L Gebhardt]

Those look like scanning issues to me, assuming color neg active film. If the film was scratched the film would let more light through, which when reversed would give a dark scratch. My guess is dust on the scanner sensor.

 

[rjbuzzclick]

If the scratches are on the film itself, look to see which side they're on. I'll bet that they'll be on the emulsion side if they're on the film. The backing paper should protect the film from scratches on the base side. One you figure out which side they're on, hold the roll up to the camera back, remembering that the images will need to be "upside down" when held against the back. Then look along your film transport for any surface the emulsion comes in contact with. There might be burr or a tiny piece of grit somewhere.

 

[Peltigera]

Those look like scanning issues to me, assuming color neg active film. If the film was scratched the film would let more light through, which when reversed would give a dark scratch. My guess is dust on the scanner sensor.

I have had the same problem recently (ie last week) with a roll of 35 mm film I had developed and scanned. I had assumed that it was the camera as it was a "new" old camera but, as you say, scratches in the emulsion will come out as black lines on a positive picture.

So, my question: how does a scanner introduce straight lines when it scans? I must admit that the scan I had done has a lot of dust on the scans (also white, suggesting opaque on the negatives).

 

[Truzi]

I'm guessing it is the scanner. It looks almost too straight for an in-camera scratch. It would have to be an awfully light scratch to retain the colors in the emulsion, but perhaps not if in the base (I'm just assuming most scratches would go all the way through emusion; I don't know much about these things).

 

[pbromaghin]

So, my question: how does a scanner introduce straight lines when it scans? I must admit that the scan I had done has a lot of dust on the scans (also white, suggesting opaque on the negatives).

If it's dust on the sensor, it will travel perfectly across the image with the scanning arm. Dust on the image or the platen is something else entirely.

 

[250swb]

There is very little DOF with a scanner lens, all too evident by the number of people who make home made adjustments to get their scanner focused. Some are better than others, but essentially if there is some dust on the scanner lens it will be so far out of focus that it couldn't show up as a sharp line.

The OP should look for something that would scratch the film, and while the backing paper offers some protection to the base side, the emulsion still gets dragged across the film gate, either supported by rollers, or with cruder cameras right across a smooth painted surface. But it looks like a processing scratch to me.

Steve

 

[LucRoMar]

I check the rollers and they looked fine, had a bit of a drama while diong so, My 3 year old son looked at te camera and put a finger through the shutter, after replacing the shutter blades I cked it worked ok, need to see if I don't get a light leak now....

For the scratces I'll dev the film tonight to see it I can see someting.

 

[LucRoMar]

ok so I did a test roll, this is indeed a scratch on the film...Now I need to find out what is doing that.

 

[LucRoMar]

or not, loaded the oter back and that one doens't advance the film... guess i am not in luck these days...

 

[brucemuir]

The rollers are notorious for breaking off at the ends of the supply side roller.
I had one repaired and here is one on the bay with the issue
http://www.ebay.com/itm/Contax-MFB-1a-/121089969596?pt=US_Film_Backs_Holders&hash=item1c31864dbc

 

[mike-o]

I had the same problem and eventually figured out it was my scanner.