Ilford Fp4, Jobo CPE-2, Xtol & Bromide drag?

[Cor]

Hi,

I recently went a group of people on a photo city trip to Rotterdam, The Netherlands.

I used my Zenza Bronica SQ 6*6, and shot FP4+ (120) at 100 ASA. I processed it in Xtol 1:1, (for this roll 150:150 ml) in my older Jobo CPE2, rotation speed 2 at 22degC for 7 minutes.

The negatives were slightly dense, but printed without to much trouble (condensor enlarger) on Ilford MGIV RC, filter 2 1/2.

Much to my surprise I noticed a phenomena which I assume to be bromide drag under these conditions (it is in the same direction of the rotation of the Jobo).

See the attachments please: first the whole print, and perhaps hard to see, there are 2 "stripes"in the sky, lighter, emerging from the chimney. Probably hard to see (it is not very obvious anyway, at least at first..), I include an enlargement of the offending area, photoshopped to enhance my point.

I am really puzzled by this: I never saw this before with FP4+ (although I mostly do portraits with this film,against a black backdrop). I do more HP5 in a Jobo, and never saw it.

What surprises me that, if I do understand bromide drag correctly that the white rim of the chimney is exhausting the developer so much that the sky '"above"" it is retarded in development. But than the sky above it should be darker due to less devlopment. But what about the vast area of black of the chimney it self, (let alone the white vertical reflection stripe, it is darker above).

Or is it the other way around, and the relative undeveloped area of the chimney is "releasing" extra developper to the sky bands?..Or..

I always thought that development in a Jobo is pretty intense.

Any insight or other suggestions on this?

thanks and best,

Cor

 

[pentaxuser]

Doesn't the CPE2 rotate in opposite directions every 4 revolutions or so to prevent this phenomenon called bromide drag? It also seems strange that this doesn't occur with HP5+ but has done so with FP4+. I presume that you use Xtol with HP5+

I suspect that the problem lies elsewhere unless your processor has a setting that turns the tank in one direction continuously.

pentaxuser

 

[Cor]

Hi,

My Jobo rotates in opposite directions, and it is the very first time I noticed this phenomena, still can not really grasp how it is possible that the lack of rotation is doing this, but what other possibilities to explain this are there?

best,

Cor

 

[hka]

Cor,
I think your rotation speed is to slow. In the past I had also some troubles with this and increased speed.
On the ATL-types Jobo recommend a speed of 75rpm in the 2500 tanks. That's what I use now.

 

[Cor]

Hi Harry,

I have an older CPE-2 with 2 speed settings, I believe that setting #1 is supposed to be 35 rpm and #2 75 rpm, I use setting #2 for Xtol, and setting #1 for PyrocatHD.

This was the first time I saw this effect. But I'll check the speed at setting #2. I did not overload the tank with 300ml, the max capacity is is 600 ml, and I try to avoid that, because the motor is having a hard time to rotate 600 ml, especially when starting up.

Best,

Cor