Film development problem

The last four rolls of FP 120 that I developed in a 4 roll nikkor type tank were a letdown. I use rodinal 1:50 for 18 minutes. I know the film was loaded properly, but thru each frame when hung vertically (not the between frame area) the middle one third is lighter than the sides, and it is the same in each frame. Other rolls taken with the same camera did not show similar problems. I aggitate for the first minute followed by 10 seconds each minute. I don't frequently use a 4 roll tank, prefering the 2 roll tank. Does the tank make a difference? Is the agitation correct? Any other ideas on what could be wrong?

Three usual problems when developing in tank are: Light leak, not enough chemistry in tank/lack of proper agitation or air bubbles so film is not complete and enough covered with chemistry, reel loading is wrong, and let say fourth is when pouring chemistry in (high) tank with many reels, maybe time for pouring/draining chemistry can be issue..

Problem on middle of film looks more to me as camera problem than tank problem, but it is just theoretical.

You said LAST 4 rolls. As rolls before were OK, maybe camera started with problem with last 4 rolls. If you want to check, run another roll through camera, develop in small tank only that roll, and if problem is still there, then it is camera issue.

Also, if you think maybe film can be issue, run roll of film with same emulsion number through properly working camera and if there is no problems, then it is not film, and you are back to developing method/equipment issue or camera issue..

If you post some images of problem, people here would be able to give you more precise answer. Sorry for not being able to help.

It sounds to me as if you're saying, trhull, that the center of the roll (the part farthest from the edges) is too light and/or the parts near the edges are too dark, all the way from the start of the roll to the end. If so, then this doesn't sound like a camera problem to me, although I could be wrong. Knowing the type of camera you've got might help, since some shutters, when misadjusted, can produce variable exposure across their travel direction.

My suspicion would be improper agitation. Note that the agitation times are only part of the equation; you've also got to consider how vigorous the agitation is, your agitation style, etc. Since you say the problem rolls were developed in a seldom-used 4-roll tank, my suspicion is that your agitation vigor or style was different when you used that tank, hence your problems. I don't have experience with tanks of that size, so I can't offer much in the way of practical advice. You might, though, want to consider using Jobo tanks and reels, which can take two rolls of 120 on a single reel. This will enable you to fit four rolls in a tank that's not much bigger than the two-roll tank with which you're more familiar. The result should be easier agitation.

I tend to agree with srs5694 that agitation is your problem, since I am working through a similar problem. I use a catechol-based developer, and used the agitation scheme recommended by the maker: gentle torus rotations for the first minute, then 2 gentle torus inversions each 2 minutes. Although my procedure (or film) did not change, awhile back my film began exhibiting higher density nearer the edges of the film than in the center. After doing some research here, I reduced the number of agitation cycles (agitated the first minute, then at 5 minutes, then at 10 minutes), increasing total development time by a couple of minutes to compensate. In addition, my agitation was much more vigorous than before, the theory being that gentle agitation disturbed the developer around the reel much more than in the center away from it, exacerbated by several more agitation cycles. I have only developed a couple of rolls this way so I cannot definitively say the problem is solved, but things look good so far.

Film Development

Thanks for responses. I am using a Rollei 2.8F which was clean and lubricated last year. The only thing I can think of, is that it is possible the prblem only appears in harse sunlight, meaning the edges may be leaking light.
I tend to think it is agitation, however, and only seems to occur using the 4 roll tank.

I'd bet money that it is an agitation problem. Put two reels in a 4 reel tank and they move around a lot when you invert it. Place 4 reels in a 4 reel tank and they hardly move at all. to compensate, you need to agitate more vigorously. It can be done. You just need to be aware that the dynamics change.

My suspicion is underdevelopment in the middle of the film strips. How many milliliters of Rodinal are you using per 120 roll?

There is a similar thread over here: (there was a url link here which no longer exists)

I use 36 ML rodinal and 1800 ML water for 18 minutes. I also use a two reel tank where the film reels also do not "slosh" around, but I never seem to have the same problem with that tank.

If the problem is from tank to tank, perhaps you have a contamination problem?

- Thomas

trhull said:

I use 36 ML rodinal and 1800 ML water for 18 minutes. I also use a two reel tank where the film reels also do not "slosh" around, but I never seem to have the same problem with that tank.

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In that case, seems like the sloshing around is causing excess agitation at the edges with overdevelopment relative to the center. Is that right? When compared to film that came out OK is the center thinner or are the edges darker?

Edges are darker, and uniformly so in all reels.

Sorry folks, print edges are darker, not the negative-disregard prior post.

trhull said:

Sorry folks, print edges are darker, not the negative-disregard prior post.

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That is the opposite of the problem I had. I experienced greater density at the edges of the film presumably caused by more movement of the developer around the film reel. This resulted in lighter edges in the print, requiring burning in.