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A student of mine developed her 4x5 film. We are trying to figure out why each negative has a relatively consistent pattern on each negative? Any thoughts? My guess is agitation when developing.

A Jobo 4x5 tank was used with a Jobo CPP auto film processor to agitate the film.

enter image description here

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    \$\begingroup\$ You’re going to have to give us a little bit more information. What was the developer, what was the agitation time, what kind of tank or development process was used. Please give us as much information as you can. \$\endgroup\$
    – Alaska Man
    Jan 31, 2020 at 17:51
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    \$\begingroup\$ What tool was used to develop these? Were they developed in the tray / canister? \$\endgroup\$
    – OnBreak.
    Jan 31, 2020 at 18:12
  • \$\begingroup\$ We used a Jobo CPP auto film processor to agitate the film. The film was in a Jobo 4x5 tank. \$\endgroup\$
    – Bess Garison
    Jan 31, 2020 at 20:43
  • \$\begingroup\$ I am thinking chemicals not mixed properly or film not loaded into the reel properly. The Jobo does the agitation automatically. I would post over at photo.net where you can have a discussion about it with a larger community of film/darkroom users, Assuming you will participate in the discussion by giving All of the pertinent info required to inform the discussion. \$\endgroup\$
    – Alaska Man
    Feb 1, 2020 at 19:00
  • \$\begingroup\$ @AlaskaMan Thank you for your suggestions. I am new to the forum :) I am waiting to be approved for photo.net because I saw they had more film development there. I have yet to hear back from my student on the exact method of agitation they used; therefore, unable to provide you all with the exact information. \$\endgroup\$
    – Bess Garison
    Feb 3, 2020 at 14:36

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So, the Jobo tank looks like this:

enter image description here

Your streaks look to be identically spaced to the support beams on top and bottom of the holder. The horizontal development line looks to be where the water level sat most often.

Looks to me like not enough liquid was used in the development phase causing uneven and streaky development.

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  • \$\begingroup\$ I am thinking that is probably what happened. I haven't seen the student to find out exactly how she agitated. The Jobo says 270 mL of chemicals which is roughly 9 ounces. I am unsure if that is per sheet of film or for the 6 sheets that the loader will fit. Any suggestions? 1 roll of 35 takes 10 ounces and 1 roll of 120 is 17.5. \$\endgroup\$
    – Bess Garison
    Feb 3, 2020 at 14:33
  • \$\begingroup\$ @BessGarison the Jobo machine should have taken care of the agitation - that's it's job, no? I haven't played much with Jobo, though can say that my SOP with my Patterson was to load it up with junk rolls, fill it to max, pour the water into the measurement device of your choice, and get a feel for what the maximum tolerable amount of liquid is. I stand develop a lot these days, so getting to max isn't hard at all. With traditional dev, you're going to have more developer than needed and so getting to max really just uses more developer than you need. But, why risk it? \$\endgroup\$
    – OnBreak.
    Feb 3, 2020 at 17:13
  • \$\begingroup\$ @BessGarison Best to figure out exactly how much liquid you need to keep the film submerged even through agitations. \$\endgroup\$
    – OnBreak.
    Feb 3, 2020 at 17:14
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I've not used a Jobo CPP but perhaps the tank was opened briefly fogging the film? The pattern of marks looks like a projection of the film reel onto the film. Perhaps this was done whilst there was liquid in the tank - hence the abrupt cut off.

The only way to solve an issue like this is to repeat it. Just make a single exposure and take it all the way through the process and see if you get the same marks. If you don't it was a one off.

[Total aside: I would be reluctant to use a big machine like a Jobo CPP with students for black and white. The complexity may cause more trouble than it is worth. (Totally needed for colour though). The best 4x5 B&W solution I've found is the Stearman Press tank. It is depressing for a student to make 6 large format exposures and have none of them work out. She should have discovered the error on the first one. That is the advantage or working with sheet film. You can adjust dev for each exposure.]

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