Tri-X '/ D76 Compensation needed for Jobo processing?

Jeffrey A. Steinberg · Feb 26, 2005

For those using a Jobo horizontal roller processor, are you using any compensation because of the near-constant agitation?

Since my Jobo processes at 74 degrees, development time for "straight" Tri-X/76 is 11 minutes. I am wondering if I should cut that a bit due to the agitation method and wanted to reach out to others who may have already tested this.

Thanks.

Bob Carnie · Feb 26, 2005

Hi Jeffrey

My time at 68 is trix d76 at 6.45- 7 min. I think your time temp is a bit high, not sure what others think but your times temp look a little hot to me.

Jeffrey A. Steinberg · Feb 26, 2005

Bob Carnie said:
Hi Jeffrey

My time at 68 is trix d76 at 6.45- 7 min. I think your time temp is a bit high, not sure what others think but your times temp look a little hot to me.

I am using an ATL-1500 which only processes at 74 degrees. You are right, I realzied my times are high. 74 degrees calls for 5.5 minutes. duh.

I see that 68 degrees you use call for 8 minutes in the data guide so you are taking off a good minute. Have I got that right?

rjs003 · Feb 26, 2005

I did some 4X5 sheet film in D76 diluted 1:1 at 68f. I did this in a Beseler drum with constant rotation. The negs. came out a little under developed for my taste so in a couple of days I intend to raise the development time to 11 1/2 minutes and see what happens.

Bob Carnie · Feb 26, 2005

Hi Jeffrey

Yes we dropped our time slightly when we swithced to the Jobo system as the constant rotation seemed a bit too much.

Ronald Moravec · Feb 27, 2005

Definately way hot. I use 5 3/4 min at 68 undiluted D76, 8 1/2 for 1:1. Decrease time 2% for each degree you go up and 15% less for rotary unless you presoak which I wouldn`t do.

My times are for a condenser enlarger. Use 6 1/4 and 9 1/2 for diffusion. Higher temp means more grain except for pyro developers.

graymatterimages · Feb 27, 2005

I agree with Ron on decreasing the time 15%. However Steve Anchell suggests diluting the developer and increasing the time to compensate for the lost sharpness produced by constant agitation.

I have noticed a drop in sharpness with 35mm negs developed by hand inversions with a stand time vs. rotary processing.

Has anybody had any success at Anchells sugestion?

felipemorgan · Feb 27, 2005

This article by John Hicks makes some claims about rotary processing which are based on his own testing but run counter to conventional wisdom and claims made elsewhere. In summary:

* Rotary processing with constant agitation does not reduce sharpness or adjacency effects

* Rotary processing does not change the HD curve significantly versus intermittent agitation

You may also want to see "To Soak or Not to Presoak" in this article where, straight from the horses mouth, Jobo provide their opinion on development time adjustments for rotary development.

FWIW, I've found that developing in the Jobo for 75% of the intermittent agitation times a good starting point.

--Philip.

Flotsam · Feb 27, 2005

My personal experience after testing several different film/dev. combos was that, after using the long 5 min. presoak that is recommended by Jobo, I had to reduce my times by 25% to 30%. This completely disagrees with Jobo who say that there should be no change in time if you use the long pre-soak but I've heard others report similar results.

I'm sorry to be so unhelpful. My only advice is to test it in your own unique darkroom conditions.

Tri-X '/ D76 Compensation needed for Jobo processing?

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