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Finding the cause of scratchs (Super-Isolette)

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Julio1fer
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Finding the cause of scratchs (Super-Isolette)

Postby Julio1fer » Sat Feb 03, 2018 10:42 pm

One of my best MF cameras is a Super-Isolette folder with an excellent Solinar lens. However, sometimes negatives from this camera showed fine scratches on the emulsion side, as in the following example (web resolution first, then a scan at 1200 dpi of the scratched area).

Image

Image

First of all I made sure it was not the developing or other out-of-camera issue. Definitely it was the camera, and they are in the negative.

The scratches were always neatly horizontal, in a band close to the upper third of the frame. The rest of the frame does not show scratches. The scratches vary in horizontal positions and intensities; sometimes they start or stop abruptly, sometimes the scratches are intense (as in the example above), but in other frames they only appear at high scanning resolution and must be identified with a loupe and good light.

Besides, the scratches were quite random, not constant. Some frames in the roll would be scratched and others would be clean. For instance, these other frames in the same roll did not have scratches at all:

Image

Image

I took the camera to the technician for advice. He inspected it thoroughly and told me that he found nothing in the rollers, film gate or other suspect parts in contact with the film. My technician is a very thorough and knowledgeable guy, and he was as puzzled as I was. I made the error of not showing him an example roll; he would probably have spotted the cause immediatly.

Because of the random pattern of the scratches, it dawned on me that sometimes I wind with the bellows closed and sometimes with bellows open. The scratches could be caused when winding the film with the bellows in the closed position, if something touches the film plane in that case. I opened the back of the camera and sure enough, when the camera is closed the lower left part of the lens is very slighty above the film plane, with a likely point of contact precisely in the scratch favorite position.

To be 100% sure, I must now do a roll remembering to always wind with the bellows open. I remember that I did wind with bellows open in several frames in this roll that were without scratches, and also that in the example above with scratch I wound with bellows closed.

Wanted to share this saga - maybe it is a silly detective story about a well-known issue. But if somebody has a similar problem it might bring some peace of mind! It took me a year and three rolls to figure out what was happening!

(Film was HP5+ in D-76 1:1)
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alexvaras
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Re: Finding the cause of scratchs (Super-Isolette)

Postby alexvaras » Sun Feb 04, 2018 2:28 am

Nice camera Julio.

I think you guessed right the reason of the scratch, lets see the next roll what happens.

In my last roll with the Retina IIa, I heard how it was scratching the neg when rewinding, not all the negs, just some in a row and stopped, same spot. I still don't know what was the cause, Im guessing I did it at -10 and the metal did shrink a bit at that temp. Need to shoot again.
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Philip
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Re: Finding the cause of scratchs (Super-Isolette)

Postby Philip » Sun Feb 04, 2018 7:33 pm

Good advice. Thanks!
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PFMcFarland
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Re: Finding the cause of scratchs (Super-Isolette)

Postby PFMcFarland » Mon Feb 05, 2018 10:40 pm

That sounds like a plausible explanation, Julio. I never wind with the camera closed for two reasons. One is what you have described, and the other is for keeping the film flatness in the focus plane. I'll wind on to about the middle of the next frame before closing the camera, then wind it the rest of the way when I'm ready to take another shot (open camera; wind; adjust shutter speed and aperture, focus, and shoot).

PF
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Waiting for the light

Julio1fer
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Re: Finding the cause of scratchs (Super-Isolette)

Postby Julio1fer » Tue Feb 06, 2018 7:16 pm

Your technique makes a lot of sense, PF, especially with red-window cameras! I'll try to get into such a discipline with folders in general.
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Bennybee
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Re: Finding the cause of scratchs (Super-Isolette)

Postby Bennybee » Wed Feb 07, 2018 3:00 pm

I always wind on right after opening my Isolette. Good advice here. Thanks.
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