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Jobo processing issue with 5x7 film
Has anyone who is processing 5x7 film in a Jobo experienced the following issue?
A sheet of film will overlap itself during processing, causing a large minus-density blemish in one corner (see the attached contact sheet, where the bottom negative has the blemish in the lower left corner). Sometimes the blemish is about twice that size.
I am confident that it is not a loading problem: the film was correctly oriented before processing.
In a recent batch, 4 out of 34 negatives were afflicted. It doesn't occur that often, but Murphy's Law assures that it will happen to the most important negatives (unlike this test example).
I have been processing 5x7 film in a Jobo since about 1999. I have seen this film overlapping issue occur about the same percentage of the time since I started. I have never seen it happen with 4x5, but I haven't processed that much 4x5.
Any suggestions? I am using the rotary speed specified in the manual. Ditto for the volume of chemistry. I am using the six-sheet drum intended for 4x5 and 5x7 film. I have thought of slowing the rotary speed and increasing the developing time. Any suggestions will be much appreciated.
Re: Jobs processing issue with 5x7 film
Suggestion:
Try a slower rotational speed if you can. I use a supporting roller under the drum and roll it by hand at a much slower speed than the Jobo. I believe the minimum Jobo speed is around 25 rpm which seems like a front-loading washing machine to me.
On the odd occasion I do get the film slipping a little even so.
I'm not sure that the amount of liquid will make a difference but it might. The most important thing is to make sure your desk and machine are level in both directions. What volume of fluid are you using?
Steve
Re: Jobs processing issue with 5x7 film
I take it that we are talking about the 3006 drum?
Does it happen randomly across all the compartments, or only in one? And are you using multiple drums or just one? The Expert Drums are hand assembled, which always leaves the potential for tiny unseen errors to creep in.
Re: Jobs processing issue with 5x7 film
Quote:
Originally Posted by
badbluesman
Has anyone who is processing 5x7 film in a Jobo experienced the following issue?
A sheet of film will overlap itself during processing, causing a large minus-density blemish in one corner (see the attached contact sheet, where the bottom negative has the blemish in the lower left corner). Sometimes the blemish is about twice that size...
Yes. Not to mention the corner scratching the part it overlaps.
Quote:
Originally Posted by
badbluesman
...I am using the six-sheet drum intended for 4x5 and 5x7 film...
I've had extraordinary results processing 4x5 in the 3006 Expert Drum. Only when using it for 5x7 does this issue arise.
Quote:
Originally Posted by
badbluesman
..I have thought of slowing the rotary speed and increasing the developing time. Any suggestions will be much appreciated.
That didn't help for me. The foolproof solution: use a 3005 Expert Drum. In my experience, chamber circumference must be substantially greater than the film dimension being inserted into it. Thus, I use a 3006 for 4x5, 3005 for 5x7 and whole plate, and a 3004 for 8x10. Once I 'bit the bullet' and purchased those additional drums, all issues ended.
Re: Jobs processing issue with 5x7 film
Quote:
Originally Posted by
Sal Santamaura
Yes. Not to mention the corner scratching the part it overlaps.
I've had extraordinary results processing 4x5 in the 3006 Expert Drum. Only when using it for 5x7 does this issue arise.
That didn't help for me. The foolproof solution: use a 3005 Expert Drum. In my experience, chamber circumference must be substantially greater than the film dimension being inserted into it. Thus, I use a 3006 for 4x5, 3005 for 5x7 and whole plate, and a 3004 for 8x10. Once I 'bit the bullet' and purchased those additional drums, all issues ended.
How is the 3005 drum different for the 3006? I've never heard of that drum.
Re: Jobs processing issue with 5x7 film
Quote:
Originally Posted by
badbluesman
How is the 3005 drum different for the 3006? I've never heard of that drum.
Re: Jobo processing issue with 5x7 film
The 3005 is the same diameter as the 3006, but it is twice as long (if not a little longer). It has 5 holes instead of 6, so they are slightly larger diameter. I had not heard of the 3004 -- but I get by with the 3005s for 8x10.
Re: Jobo processing issue with 5x7 film
Quote:
Originally Posted by
Vaughn
...I had not heard of the 3004...
That model was discontinued a looooong time ago. Last year, I managed to acquire two more to go with the one I already bought with my processor in 1998:
Re: Jobo processing issue with 5x7 film
I noticed that 5x7 film seems to extract itself slowly from the tube during processing in a 3006 drum if I insert the film too deeply in the tubes. Keeping the film flush with the top of each tube seemed to solve the problem for me. There's a chamfer at the bottom of each tube that will turn the film coil slightly cone-shaped if it's bottomed out, possibly allowing more turbulence behind it. This might be unrelated to your problem, but thought I would mention it.
Re: Jobo processing issue with 5x7 film
Also, make sure that both sides of the film are perpendicular to each other before you cap the tank.
Thomas
