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09-01-2020, 05:37 AM   #1
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Regular Marks on Negatives

Hi everyone,

I have been shooting with my Pentax 67 for a number of years and on a few recent rolls I have had some mark appear on my negatives. It is fairly irregular on which frames but the marks are always in the same place - top left and bottom right of the frame, long white lines, right along the edge of the frame as seen in the attached image below (please disregard the dust spots!):


Any ideas what it could be?

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09-01-2020, 06:41 AM - 1 Like   #2
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maybe light leaks?
09-01-2020, 11:25 AM   #3
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Who processes the film? It could be an agitation issue.
09-01-2020, 01:21 PM   #4
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I don't think agitation explains marks that only appear at frame edges. From what I can see from the one example shown, I might suspect a light reflection from the edge of the film gate. You also get similar things showing up on the very edges of prints made with a negative in a shiny edged film holder.

Interior surfaces in a camera need to be as non-reflective as possible - matte black, or flocked black surfaces help. Shiny black metal is still shiny. If you see a shiny surface or two right at the film gate (lock the shutter open on bulb to inspect it - not easy on a medium format camera. Multiple exposure mode can help) then reducing shiny surfaces with some matte black paint may indeed help.

09-01-2020, 01:41 PM - 1 Like   #5
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Density streaks caused by a improper agitation profile. Or the film is wound too tight on the reel thereby having a thin gap between wraps and not getting good boundary layer replenishment. And edges of the film in the reel can sometimes not develop evenly too. This is more common than the density streaks in the middle of the film area.
09-01-2020, 04:08 PM   #6
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QuoteOriginally posted by tuco Quote
Density streaks caused by a improper agitation profile. Or the film is wound too tight on the reel thereby having a thin gap between wraps and not getting good boundary layer replenishment. And edges of the film in the reel can sometimes not develop evenly too. This is more common than the density streaks in the middle of the film area.
Hi Tuco,

Thanks for the reply - can you explain how the edge of the film can sometimes not develop evenly across the negative? Especially given these are vertical lines when the negative is sitting horizontally in the tank? I had a quick look at some c41 negs and coulnd't see the mark so it indicates to me it is a developing issue and I dev'd these rolls at home myself.

Cheers,
Dave
09-01-2020, 04:31 PM   #7
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I see less lighter density on all 4 sides of the sample as well as some darker spots on the right half of the bottom.

How did these get digitized? Did you pre-soak the film prior to developer? That is by far the easiest remedy for many issues. 1 minute with water at developer temp and thorough, gentle, agitation generally does the trick.
09-01-2020, 05:32 PM   #8
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QuoteOriginally posted by JohnMc Quote
I see less lighter density on all 4 sides of the sample as well as some darker spots on the right half of the bottom.

How did these get digitized? Did you pre-soak the film prior to developer? That is by far the easiest remedy for many issues. 1 minute with water at developer temp and thorough, gentle, agitation generally does the trick.
Thanks John,

I run a three minute pre soak prior to developing (at temperature). I scanned these myself on flatbed scanner.

09-01-2020, 05:41 PM   #9
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QuoteOriginally posted by davewell83 Quote
Hi Tuco,

Thanks for the reply - can you explain how the edge of the film can sometimes not develop evenly across the negative? Especially given these are vertical lines when the negative is sitting horizontally in the tank? I had a quick look at some c41 negs and coulnd't see the mark so it indicates to me it is a developing issue and I dev'd these rolls at home myself.

Cheers,
Dave
First, density streaks can be caused by several things. I mention agitation because of the 'streaking nature'. However something like exhausted or too small of an amount of developer can be a source too.

In small format, streaks around the sprocket holes are good indication of an agitation problem. Similarly, the fluid flow around a 120 developing reel common to the film's edge can be a source poor replenishment during an agitation cycle. I get that edge effect often when everything else on the negative developed fine. I bet most do-it-yourselfers have at one time or another.

If you're using the same developer (that's in good shape) and the same agitation profile you used before with success, then maybe the scanning/contrast curve adjustment is too aggressive for an over/under exposed negative kind of thing.

Would you care to share the film, developer and agitation profile you use?
09-01-2020, 05:45 PM   #10
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QuoteOriginally posted by davewell83 Quote
I have been shooting with my Pentax 67 for a number of years and on a few recent rolls I have had some mark appear on my negatives. It is fairly irregular on which frames but the marks are always in the same place - top left and bottom right of the frame, long white lines, right along the edge of the frame as seen in the attached image below (please disregard the dust spots!):
a) On the next roll after loading the camera, use black camera tape on to seal any areas where light could be entering the 67.

b) Are you using metal or plastic reels?

c) Do you pre-wet your film before the developer?

d) What is your method of agitation?

e) Did you change film stock when the issue started? Or has this happened on different emulsions (Tri-X, HP5+, Delta, etc)?
09-01-2020, 06:12 PM   #11
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QuoteOriginally posted by davewell83 Quote
Thanks John,

I run a three minute pre soak prior to developing (at temperature). I scanned these myself on flatbed scanner.
Do you have a loupe and light table? You should be able to see those density changes; are they consistent frame to frame?
09-01-2020, 06:34 PM   #12
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QuoteOriginally posted by tuco Quote
First, density streaks can be caused by several things. I mention agitation because of the 'streaking nature'. However something like exhausted or too small of an amount of developer can be a source too.

In small format, streaks around the sprocket holes are good indication of an agitation problem. Similarly, the fluid flow around a 120 developing reel common to the film's edge can be a source poor replenishment during an agitation cycle. I get that edge effect often when everything else on the negative developed fine. I bet most do-it-yourselfers have at one time or another.

If you're using the same developer (that's in good shape) and the same agitation profile you used before with success, then maybe the scanning/contrast curve adjustment is too aggressive for an over/under exposed negative kind of thing.

Would you care to share the film, developer and agitation profile you use?
Thanks for the detailed response;

These were all shot on Ilford Delta 100, developed with D76. It could be an issue of the developer becoming exhausted as you mentioned although for this instance and newer examples, the film developed is never more than 2 months old.

I usually agitate four times once the developer is in and then 3 times every minute of development ( dev time is 11 minutes).
09-01-2020, 06:47 PM   #13
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QuoteOriginally posted by Alex645 Quote
a) On the next roll after loading the camera, use black camera tape on to seal any areas where light could be entering the 67.

b) Are you using metal or plastic reels?

c) Do you pre-wet your film before the developer?

d) What is your method of agitation?

e) Did you change film stock when the issue started? Or has this happened on different emulsions (Tri-X, HP5+, Delta, etc)?
QuoteOriginally posted by davewell83 Quote
Thanks for the detailed response;

These were all shot on Ilford Delta 100, developed with D76.
I usually agitate four times once the developer is in and then 3 times every minute of development ( dev time is 11 minutes).
Ok, so probably not agitation. My recommendation is to work on a process of elimination. Try any roll other than Delta 100. If it's still there, it's not a bad batch from Ilford.

Again, metal or plastic reels? Do you pre-wet (room temp water for 30 seconds before the developer stage)?
09-01-2020, 08:05 PM   #14
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QuoteOriginally posted by Alex645 Quote
Ok, so probably not agitation. My recommendation is to work on a process of elimination. Try any roll other than Delta 100. If it's still there, it's not a bad batch from Ilford.

Again, metal or plastic reels? Do you pre-wet (room temp water for 30 seconds before the developer stage)?
I use plastic reels and run a three minute pre-soak prior to development. This is with water at 20 degrees (celcius)

---------- Post added 09-01-20 at 08:10 PM ----------

Just a quick update: Looking back on other rolls where this is an issue: it seems to mostly occur on the last frame or two of the roll. I can't see how this would be an in camera problem meaning it must be happening in development. For reference, I roll the film on from frame 1 - so the last frames shot are on the outside of the reel. I wonder if it could have occured because the end of the roll wasn't wound past the catchment area.? Seems odd that it is on the same spots (edge of the frame) in multiple shots.
09-01-2020, 08:29 PM   #15
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QuoteOriginally posted by davewell83 Quote
I usually agitate four times once the developer is in and then 3 times every minute of development ( dev time is 11 minutes).

That's Ilford's agitation profile. Just make sure your tank inversions are not too gentle and you're mixing the fluid well.

Kodak's D-76 agitation profile is twice as frequent (and more vigorous for T-Max films). Either agitation profile shouldn't be a problem for density streaks but I'd point out that using say a Kodak development time with an Ilford agitation profile should yield a slightly under developed negative. Kodak and Ilford establish their development times using their agitation profiles. And if you shake the film twice as much it will effectively 'speed up the film', for example.
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