Jobo Expert?

[eman]

Dude,-->

Here is a mono and bi-directional density comparison of an image of grey tone, created by my Agfa Alto film recorder. Marked are the spots I read w/my densitometer, (till I sold it here on LFPF) and you can see, except where I TR'ed the readings at the top, there is not enough variation in the density to say so.

I processed 2 sheets separately in a 3010 on a CPP2, one with mono and the other w/bi-directional agitation and took the readings from those. This test was actually just to verify that mono and bi directional agitation produce the same results basically.

I never liked the design of the Jobo expert tank system and after a test my biggest fear was confirmed. The test was simple, 300ml of pyrocat-hd and one sheet of 4x5 using a 3010 tank. The densities are different in both ends of the negative.

I'm sure that with non-staining and/or a larger volume of developer the results are not that obvious but the problem is still there.

Any comments?

[ic-racer]

I never liked the design of the Jobo expert tank system and after a test my biggest fear was confirmed. The test was simple, 300ml of pyrocat-hd and one sheet of 4x5 using a 3010 tank. The densities are different in both ends of the negative.

I'm sure that with non-staining and/or a larger volume of developer the results are not that obvious but the problem is still there.

Any comments?

You just demonstrated that under those conditions 300ml is not enough developer. Two things that people tend to skimp: exposure and developer volume

[eman]

Here is a scan of the Jobo capacities for their expert drums.Attachment 72332
I process in pyrocat, mostly rolls though, in my jobo and somewhat exceed those recs in the 1500 series drums. Most recently I ran a large number of 8x10 sheets in my 3005 for a client and once they were in his hands he sent an email saying "I spent the afternoon in the darkroom yesterday and the negs are printing up beautifully! Good call on all the times, thanks a bunch"
I use a slow rotation and in the case of these 8x10's, to lessen wear and tear on the old gal, I ran them mono-directionally. In the case of the 8x10's I don't think I exceeded the volume recs by much if at all.

[Greg Blank]

I dare say that peoples exposing light sources are the single biggest variable. Objectively looking at it; its unlikely that the enlarger,sun, photo floods or any other light source will not produce some variance that will be deemed of no consequence by the uninformed. The halogen light sources of enlargers can vary by ten lux or more from center to edge- same with regard to the sun, photo floods and strobes.

[mandoman7]

Aside from the question of uneven development, which is generally held to be more true for tank and tray development than drums, the use of 300ml of pyro introduces a possibility of developer exhaustion from what I've read (not tested). This would be exacerbated if the drum was not level, and there was a thin amount of solution on the film.

[Kimberly Anderson]

Thank you for the mono and bi-directional rotation test and densitometry readings. Very interesting. If I read your data correctly I am seeing roughly a .20 increase in density regardless of the sampling location from the mono-directional processsing. This validates what I have been seeing with my own processing even though I haven't been doing any scientific readings.

Very nice.

[SamReeves]

I use the 3005 and 3010 tanks and after discovering what you did, I started using a minimum of 600-700 ml of developer and have had beautiful results ever since.

Looks to be the consensus here.

This is what I've been up to myself. It kinda sucks, but better safe than sorry. And I have the sucker perfectly level, but it does require more chemistry than Jobo advertises. The best thing you can do is grab some old film, and test the chemistry levels until you see no defects.

[Lachlan 717]

This is what I've been up to myself. It kinda sucks, but better safe than sorry. And I have the sucker perfectly level, but it does require more chemistry than Jobo advertises. The best thing you can do is grab some old film, and test the chemistry levels until you see no defects.

From 300ml to 600ml using Pyrocat-HD is using 3ml extra of A and B. As I wrote earlier, a trivial amount.

Why take the time to test minimum volumes when you know that this will do the job? In my opinion, a priggish, needless exercise.

[eman]

I've never come up short in developer volume resulting in unevenness whether running at the Jobo rec. levels or higher. For pyrocat I use more but it's also the math involved. Sometimes it's easier to just make it 100ml greater than Jobo said.... or now 'says' since they are making processors again. Best to keep me and math as far apart as possible as I'm terrible at it so I go with what's easiest to figure out for the total volume and doesn't leave me with a total of 183mls or the like.
Anywho, even times where I've forgotten the pre-wet step I've had 'perfect' negs. They were certainly even anyway.

Ya, math and typing, I suck at that!

[Greg Blank]

Ugh, we cave people never use the 3 R's We just develop photo'd films, in our holes, in the far end of east bund *F*.