120 film occasional fogging

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Janahurt

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Hi I use a Hasselblad A12 back(s) and I get this fogging throughout the middle of the roll of film sometimes. I think it's from loading/unloading and maybe the rolls gets slightly loose. This last roll seemed "good" to me when i unloaded it so I thought I'd ask. here's an example https://imgur.com/a/hOVJmJl . The second image is just exaggerated obviously. Any thoughts?

Thanks
 

winger

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I think it's the seals around where the dark slide goes. If it was because the roll wasn't wound tightly enough, then the edges would have been light struck more than the middle instead of the middle more than the edges.
 
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Janahurt

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Hi I use a Hasselblad A12 back(s) and I get this fogging throughout the middle of the roll of film sometimes. I think it's from loading/unloading and maybe the rolls gets slightly loose. This last roll seemed "good" to me when i unloaded it so I thought I'd ask. here's an example https://imgur.com/a/hOVJmJl . The second image is just exaggerated obviously. Any thoughts?

Thanks

Q
I think it's the seals around where the dark slide goes. If it was because the roll wasn't wound tightly enough, then the edges would have been light struck more than the middle instead of the middle more than the edges.

Maybe it’s when I put it on the spool to develop- if it was darkslide seal wouldn’t the side be overexposed as well? Maybe my changing room is not completely light tight during the day.
 

glbeas

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A good way to test that would be to cover the slot and see if it stops the problem. Either way it sounds like the back needs servicing.
 
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Janahurt

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A good way to test that would be to cover the slot and see if it stops the problem. Either way it sounds like the back needs servicing.

If it’s not the light seal what reasons will the back need servicing?
 

glbeas

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There are seals all around the back, any one of them may be defective. It might be a job you can do yourself, as the Bronica backs are. Lets hear from some more experienced Hassy users on this.
 

winger

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if it was darkslide seal wouldn’t the side be overexposed as well?

The seal may be bad more in the middle than the edges - it's not necessarily the whole thing that's bad, but you can't change just part of it. And it also matters how the light hits it when the dark slide is out. I'd suggest doing several shots in bright sun with the dark slide slot covered by something definitely light tight and then a few frames where you don't. Then at least you'll know.

As for your changing room - if you make it dark and stay there for twenty minutes, can you see your hand in front of your face? If it's completely dark, you won't see it. And light in the changing room wouldn't get only the middle and always the middle. If that's the only part of your films that have had extra exposure, then it's happening at a time when most of the film is blocked.

What type of tank and reel are you using to develop it?
 
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Janahurt

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The seal may be bad more in the middle than the edges - it's not necessarily the whole thing that's bad, but you can't change just part of it. And it also matters how the light hits it when the dark slide is out. I'd suggest doing several shots in bright sun with the dark slide slot covered by something definitely light tight and then a few frames where you don't. Then at least you'll know.

As for your changing room - if you make it dark and stay there for twenty minutes, can you see your hand in front of your face? If it's completely dark, you won't see it. And light in the changing room wouldn't get only the middle and always the middle. If that's the only part of your films that have had extra exposure, then it's happening at a time when most of the film is blocked.

What type of tank and reel are you using to develop it?

I see in section 3 another seal, looks like another on the opposite side too maybe. http://www.galerie-photo.com/manuels/hasselblad-magasins.pdf . If it's one of those, wouldn't the leak be from the side? This seems to be from the direct middle and diffusing outward. I went to my changing room for over 5 minutes (sorry not 20) and it is 100% pitch black. This leads me to think it's fogging either before loading, after unloading, or after it's put in the steel developing tank with plastic top. I thought maybe my fingers are masking the edges while putting it on the reel, but the dark room shows it's not that. It doesn't happen all the time, but when it does it's the whole roll i think. I don't think I've seen it with store processed film. Here's a scan showing it from a positive point of view. https://imgur.com/a/qGL84go

This is Tri-X 400.

By the way thanks for the effort being put into this.

edit: The first example image shows the "end of the roll" film that's about 6cm long which even has it fogged. That little bit is zipped by when I finish winding, but it's fogging is equal to the rest of the roll. I think that means the fogging is taking place independent of the back since the frames where it "sits there" are not completely blown out. I guess it does take more than 5 minutes to adapt so I"ll try that again. https://en.wikipedia.org/wiki/Adaptation_(eye)
 
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Janahurt

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That is probably it - my dark room is not completely dark. After about 8 minutes I could see a little light coming from under the door. I think I usually develop at night with the basement lights off - so there was no light to come in. Yesterday was during the day so sunlight and lightbulbs were on. I'll try developing at night from now on because getting this door light tight is proving to be very difficult. Thanks everyone!
 

REAndy

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My dark room is in the utility room in the basement. One time, I was loading film onto a real, and my wife (in the kitchen up-stairs) started to wash some dishes. In the total darkness, I heard the water heater turn on. (it's natural gas). I could see the glow of the flame on the floor. I thought my darkroom was totally light tight... It is, but not when the water heater turns on.
 
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