Odd higher density marks on RA-4 print; probably an optical issue.

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Tom Kershaw

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strange_mark_kp800.jpg


Firstly, I have processed and printed several rolls of colour negative film recently (although not Portra 800), exposed with my Bronica SQ-B, and not come across the illustrated density marks once. I've not yet scanned the film in to check whether it is on the negative itself, but I do suspect an optical issue as the density mark has appeared on black & white film as well, but again only the RF645 negatives. I've printed other frames from the same roll to 12x16" and not found the marks present.

Has anyone else come across this particular problem?

Tom
 

dpurdy

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That hair would not cause the plus density. IF you are getting it with various films all from the same camera I would suspect it is some how a light leak or reflection problem with the camera though I know nothing about this camera.
 

nickandre

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Did you try printing a blank frame or changing enlarger lenses? You can also try cleaning your enlarger head. How are you processing the film? It could be a light leak in camera. Try running some 3200 speed film though the same film back and seeing if they're any worse.
 

DanielStone

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same place in every negative that you've shot through that camera? I'd suspect light leak if its in the same relative place on every neg.

break out the ground glass and put 'er on bulb, open here up, and see if you can find the light leak(if its from the lens side) it might be coming through on the back too

-Dan
 
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Tom Kershaw

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same place in every negative that you've shot through that camera? I'd suspect light leak if its in the same relative place on every neg.

break out the ground glass and put 'er on bulb, open here up, and see if you can find the light leak(if its from the lens side) it might be coming through on the back too

-Dan

I've had the camera for over 3 years and only recently have I experienced these marks. I'll run a few tests.

Tom
 

DanielStone

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Tom,

make a contact sheet, or just look at the negs on a lightbox, or a monitor with a white background, such as here on APUG :smile:!

faster than scanning, etc....

you should be able to see them on the negs, since those seem to be quite pronounced.

-Dan
 

BobNewYork

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I recently got a similarly shaped mark on two negs out of 15 films from my Bronica GS-1. Very similar shape and size - but more diagonal. They appeared in the same place on a consecutive two of four negs taken at the same time with the camera unmoved, on a tripod and with the same lens. (I was using different filters etc.) The scene was in Scotland and very similar to yours Tom - big sky landscape etc. It's definitely higher density on the neg and looks to me like a slight light leak or perhaps sun catching a filter ring or something and flaring back into the lens. Of course, the best of the four negs was affected - well we knew that, of course!

The good news is that his neg was taken early in the trip and was on the first or second film and those two negs were the only one's to exhibit the problem. I'm going to ignore it until or unless the problem arises again.

Bob H
 
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Tom Kershaw

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I recently got a similarly shaped mark on two negs out of 15 films from my Bronica GS-1. Very similar shape and size - but more diagonal. They appeared in the same place on a consecutive two of four negs taken at the same time with the camera unmoved, on a tripod and with the same lens. (I was using different filters etc.) The scene was in Scotland and very similar to yours Tom - big sky landscape etc. It's definitely higher density on the neg and looks to me like a slight light leak or perhaps sun catching a filter ring or something and flaring back into the lens. Of course, the best of the four negs was affected - well we knew that, of course!

The good news is that his neg was taken early in the trip and was on the first or second film and those two negs were the only one's to exhibit the problem. I'm going to ignore it until or unless the problem arises again.

Bob H

I've just printed some negatives from a roll only exposed with the 45mm lens and still found these marks on the prints; so perhaps it is a light leak. Next thing is to expose some film on blue sky with the Bronica SQ-B as a control. The RF645 exposed film is completely clean otherwise, no loose film type black markings on the edge of the film etc.

Tom
 

BobNewYork

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Is the 45mm lens tight when it's mounted? Maybe the darkslide is warped? I hate these intermittent problems - you can't find anything to fix and you live in fear of them !! No better than cars !!!

Bob H
 

BobNewYork

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I just looked at the contact sheet again, (would love to post it - but I can't scan for the time being) and the light definitely changed. In my case I took four frames in relatively quick succession with the camera tripod-mounted and with the same lens. The difference in the frames was two with and two without a G2 filter and an exposure variation of 2/3 stop for each of the two "sets". The mark shows on one filtered and one unfiltered frame but it's clear that the light changed. (It was in the U.K. !) The more I look at it, the only thing I can conceive is a freak reflection into the lens from something. I was using the 100mm macro so I'll get that out later and see if I can see any bare metal on any part at the front. I also tend to stand right up next to the camera when it's tripod-mounted, so it could have been something I was wearing!

Many years ago I had a similar incident with a different outfit. It stopped me trusting the camera for a long time, though I did use it - and it never happened again. I'm not going that route again though. I'll just keep using the system.........until it comes back to bite me in the arse!

Bob H
 

BobNewYork

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Wow - I'd never have gone there Tom! Glad it's sorted though - you can take photographs with your mind at ease!!!

Bob H
 
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Tom Kershaw

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Well Bob, the plot thickens, I'm now not so sure it is the lens...

See this:
scratch_marks_meopta_mag_4.jpg


The scratches line up with the density marks seen in prints. In the Meopta Magnifax the metal lens carrier sits close to the the diffuser so it is entirely possibly that I have bashed the carrier up against the plastic on multiple occasions.

Tom
 

BobNewYork

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Looks like you've found the culprit Tom. The fact that you didn't notice this on other negs may be due to the fact that the marks "lined up" with higher density portions of those negatives. I wonder if the black marks are residual paint from the negative carrier. The scratches probably wouldn't be a big problem if they didn't have density. Perhaps that could be cleaned out. Alternatively you should be able to replace the diffusion material. I don't know if Meopta sells this part - and even if they don't, some other neutral diffusion material should work. The alternative, of course, is to take only photographs with highlights in those exact areas. :tongue::tongue: Guess not!

Seeing the Meopta takes me back. I used to sell Meopta enlargers at my Dad's shop back in the sixties and seventies in Surrey. ( Aahh - the "Good Old Days" - back when men were men and wore floral shirts and bell-bottomed jeans :D:D)

Post how it works out Tom. Good luck mate.

Bob H
 
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