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-   -   A12 back - light leak or user error (http://www.rangefinderforum.com/forums/showthread.php?t=169493)

nickthetasmaniac 09-13-2019 03:26

A12 back - light leak or user error
 
G'day everyone,

I just ran a test roll through a 'new' A12 back on my SWC/M. The first 11 frames were all good, but the final one was like this... Any ideas what's going on?

User error my end?

User error with development?

The only issue I can think of with the back itself is that the spacing seems excessive compared to my other A12's. But if that's the case why would half the last frame be over-exposed? Wouldn't it just reach the end and prevent me from fully winding on the last frame?

Thanks!

Ektar100679 by Nick Clark, on Flickr

Ektar100639 by Nick Clark, on Flickr

charjohncarter 09-13-2019 10:43

I hate light leaks. They come from the most unusual places. This looks like a loading, spacing, or dark slide error. I'm not a Hassy expert, so I'll just kick this to the front as nobody responded.

CharlesDAMorgan 09-13-2019 10:49

Dark slide error would manifest on the side, not top I would have thought. Check play there though. Same with end of reel too. Unless you were shooting on its side (unlikely!).

I wonder if it is light seals in the film back. The last frame is most vulnerable as the back is removed for final winding and film removal - the rest of the frames are protected within the back and by the camera body.

Richard G 09-13-2019 11:05

If the spacing was increased you may have wound on a bit too far on the magazine insert, beyond the two arrows on the film, before inserting it into the A12 casing. That might lead to one less shot on the roll: did you get 12? Indeed it looks like maybe you just lost the last bit of the film emulsion cutting off the bottom of the last frame (which is the top of the last image). I don’t know anything about malfunctioning backs and what they produce but I agree it would be odd with a light leak to get only one frame affected. I’d say it’s just how you set up the magazine insert.

Richard G 09-13-2019 11:18

Loading a Hasselblad seems to have only two possible errors: where you place the roll in relation to the start arrows on the film. And forgetting to wind on ten revolutions to get the emulsion to the film gate. The latter often leads to losing a frame if you’ve accidentally exposed the film paper before realising. The back now wants you to advance one frame, wasting the first frame now in the exposure position.

Bill Clark 09-13-2019 11:42

I leave the dark slide out of the film back. Seal at max expansion.

My reasoning:

The dark slide, when installed, compresses ever so slightly the rubber gasket. At some point, the gasket gets tired, hard with age, doesn’t expand after dark slide removal, causing a light leak.

When in business, I had several Haselblad cameras and changed camera rather than film back. Another person would reload and film back doesn’t need to be removed from the camera for that to take place. The day moves too fast. I concentrated on what’s happening in front of the lens.

I’ve nrver had a light leak and never replaced any seals. Some of my cameras are from the late 1950’s - early 60’s.

Maybe I’m due for a light leak issue!

mpaniagua 09-13-2019 11:43

I think it is dark slide error. Dark slide wasn't probably pushed all the way in.


Marcelo.

Richard G 09-13-2019 16:48

If this is colour negative film then the band of white at the top of the affected image is not from a dense negative exposed to light, it's from something much denser still: black backing paper of the film roll. The short chromatic line of the last colour is also consistent with the end of the emulsion. This is not a light leak.

nickthetasmaniac 09-13-2019 17:07

Quote:

Originally Posted by Richard G (Post 2912104)
If the spacing was increased you may have wound on a bit too far on the magazine insert, beyond the two arrows on the film, before inserting it into the A12 casing. That might lead to one less shot on the roll: did you get 12? Indeed it looks like maybe you just lost the last bit of the film emulsion cutting off the bottom of the last frame (which is the top of the last image). I donít know anything about malfunctioning backs and what they produce but I agree it would be odd with a light leak to get only one frame affected. Iíd say itís just how you set up the magazine insert.

I got 12 frames, and the burnt section was the last part (1/3?) of the 12th frame.

I'll try another roll and be as careful as possible loading.

Quote:

Originally Posted by mpaniagua (Post 2912112)
I think it is dark slide error. Dark slide wasn't probably pushed all the way in.

I don't think it was the dark slide. First, it was definitely pushed all the way in. Second, it's across the top of the frame, not the side.

nickthetasmaniac 09-13-2019 17:08

Quote:

Originally Posted by Richard G (Post 2912153)
If this is colour negative film then the band of white at the top of the affected image is not from a dense negative exposed to light, it's from something much denser still: black backing paper of the film roll. The short chromatic line of the last colour is also consistent with the end of the emulsion. This is not a light leak.

I think you might be right. I'll try another roll and see how it goes.

gbealnz 09-14-2019 00:48

Have a decent look inside the mag as well, just in case it's s segment of backing paper.
Gary

Rob-F 09-14-2019 06:01

Quote:

Originally Posted by Richard G (Post 2912104)
If the spacing was increased you may have wound on a bit too far on the magazine insert, beyond the two arrows on the film, before inserting it into the A12 casing. That might lead to one less shot on the roll: did you get 12? Indeed it looks like maybe you just lost the last bit of the film emulsion cutting off the bottom of the last frame (which is the top of the last image). I donít know anything about malfunctioning backs and what they produce but I agree it would be odd with a light leak to get only one frame affected. Iíd say itís just how you set up the magazine insert.

Quote:

Originally Posted by Richard G (Post 2912153)
If this is colour negative film then the band of white at the top of the affected image is not from a dense negative exposed to light, it's from something much denser still: black backing paper of the film roll. The short chromatic line of the last colour is also consistent with the end of the emulsion. This is not a light leak.

Seems a lot depends on whether it really is at the end of the roll. If it is, I believe Richard has nailed it. Nick, is that "false chromatic line" all the way to the end of the film? I'm puzzled because that area doesn't look evenly spaced from the top of the frame in your picture. If it's the end of the film, it ought to be. Still, the wide frame spacing really does suggest you ran out of film.

Godfrey 09-14-2019 08:39

User error? Mechanical fault? Hard to say.

Carefully Load and expose another roll of film. See if the frame spacing is still too wide, and if the last frame is cut off again. If it is on either count, the back needs servicing.

G


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