jobo 2500 series : uneven development

Greetings,
I recently acquired a 2500 series jobo tank, I believe the 2553. In my second attempt to hand process I purchased a jobo roller base. I photographed an overcast sky on three separate 120 rolls and processed all in D-76. Regardless of developer/film combo, what I noticed was that each roll was consistently unevenly developed. From one end to the other each roll's density increased.

My hypothesis:
The film end closest to the center was being submerged in the developer more often than the outer portions of the film, causing a gradation of development.

Notes:
- i had only rinsed for 2 minutes.
- My agitation was slow/steady, switching direction every 30 sec.
- The jobo 'how to' portion of the website, states rotation should be 'P'/75.... I don't know what that means.

I am eager to continue my testing and figure this out, before I move on to the 4x5 testing of the tank. Any suggestions as to how I could go about getting even development would be greatly appreciated.

best,
Victor

More info please.
How much liquid?
How did you load the reels? Film on the outside? Inside of the reel? Or two rolls on the same reel?

If you're spinning then the inner part gets the least amount of chemicals.

Roller base requires constant spinning. The P/75 is for the processor don't worry about it.

photo_ojo said:

My hypothesis:
The film end closest to the center was being submerged in the developer more often than the outer portions of the film, causing a gradation of development.

Click to expand...

This would be true only if you loaded the reels all the way to the inside of the reel, i.e. all the way to the center core, leaving the empty space on the outer part of the reel - which is NOT how you load the film if you want to use rotation. If you use "normal" way of "hand" developing in a tank, it doesn't matter. But, for rotation, the film must not be threaded all the way to the core. Or, it may - but then you must fill the tank/drum almost completely - according to instructions, which can be found on the web, e.g. HERE.
You'll see that the quantity of chemicals if you use ONE 120 film per reel is lower than if you want to use TWO films per reel.

Some (newer) Jobo reels have a red tab, with instructions that you load the 120 film only until you reach the red tab. The way to load it is to "thread" the film in only until you reach the end of the film - do NOT thread it any more - i.e. closer to the center. The red tab is used when you load TWO 120 films on the same reel, preventing overlapping of the negatives.

Jobo instructions say the following:
"Continue walking the film onto the reel until the end is fully into the reel."

(by "walking" I guess they mean "threading", or whatever you want to call the method by which you insert the roll onto the reel).

Denis

Dear Victor,

The approximate speed for rotation is 75rpm. If I had to bet (and others have noted) you probably loaded the film in without the red tab in place but only used 650ml rather than the 1250ml required when 2 rolls per reel are loaded, separated by the red tab. It might also be that the tab was never engaged and the film worked it's way towards the center.

I have used the 2551 a myriad of times with 4x5 and the newer reels that have the black separators and never had problems with uneven development. You should fare well in that regard. (BTW: I use 600ml rather than the minimum specified 560ml for ease of measuring.)

Good luck.

Neal Wydra

Thank you all for your replies. In regards to the questions:

- I did not load the film to the center. When taken off the reel the film had no apparent signs of having moved in any further toward the center.
- I used 400ml instead of what I thought had been recommended for three rolls of 120 @ 330ml. Perhaps this is the wrong data sheet.
- the spinning was constant. Should I use more/less chemistry?

I will try again this weekend and repost my results.

thanks again.

Dear Victor,

The advised fluid volume for 3 rolls of 120 is 640ml. It should be printed on the side of your tank. Look here for more info: Dead Link Removed

Neal Wydra

If he loaded three rolls on the outside of three reels then 330 is right.

Hi Nick,

Victor states that he has a 2553 tank, not a 2523. For a 2553 tank 330ml is not enough.

Neal Wydra

It is if you load the exterior of the reel with 120 film.

Dead Link Removed

Check the link you posted -) I do this for C-41. I use dilute developers of B&W so it's not an issue.

..... well from how I read the chart on the above links, 1x 120 = 3 rolls @ 330ml and 2x 120 = 6 rolls @ 640 ml. I used 400ml(an assumed middle ground I think). So my next tests will be: 3 rolls 120 @ 330 ml / 5 min presoak , and then another set : 3 rolls 120 @ 640 ml / 5 min presoak.

a new post with images nest week.

Is it agreed upon then that the uneven development is due to the lack of chemistry? or could it be the way I am agitating?

It just so happens that UPS delivered a 2553 tank and 3 reels to me last Tuesday. I haven't used it yet. My experience to date is with a 2523 tank and 1 reel loaded with 1 roll of 120 film or a 3010 Expert tank loaded with 1 to 6 sheets of 4x5 film. Pre-soak 2-5 minutes. Developers: Some in D-76 1:1 but mostly Xtol 1:3. Volume: Minimum of 400ml for 1 roll of 120 in the 2523 or 2 sheets of 4x5 in the 3010. I have used 800ml for 6 sheets in the 3010. Agitation: Either a Uniroller with reversing action or a single direction Beseler moter base. Time: 8 to 15 minutes so far. Results: Uniformly developed negatives.

Some observations:

I tried manually rotating the 2523 tank once. That was punishment enough for me. I then found and bought the Uniroller motor base for $20. Best $20 I ever spent.
I got the Beseler motor base for free with a car full of darkroom hardware. I have been using it in place of the Uniroller thinking that the continuous direction rotation was better. Maybe that's right and maybe not. The negatives look fine from either motor base.
The Beseler turns the 3010 tank at 30-31 RPM and the smaller 2523 tank at 45 PRM.
The Uniroller reverses direction at about 365 or 370 degrees with the 2553 tank. The 3010 tank reverses direction at about 170-180 degrees. Based on those two observations, I'm inclined to use the Uniroller with the 25xx tanks and the Beseler for the 3010.

The 2553 will hold approximately 1300+ml without dribbling. On the other hand, that might be a heavier load than my motor bases can handle. As I am using a little developer and a lot of water I may need to cut back on the number of rolls in the 2553 or cut back on the dilution. We shall see.

330ml or 640ml? I say round up to at least 400ml and 700ml. Developer is cheap. Use a lot.

Good luck and YMMV.

Hi NIck/Victor,

I see that I was wrong in reading the chart. 330ml is indeed the amount advised for the setup Victor used and I am confident that Jobo knows the correct amount of fluid required.. This leads me to believe that it might be an exposure issue rather than a lack of fluid volume. Looking at the little arrows on the film it does not, to my eye, appear that there is a trend in their appearance.

Neal Wydra

The Jobo info is a bit confusing. It's not really the number of rolls. It's how you load the reels. For example if you load three reels with one roll per reel [3 rolls total] and all three reels are have the film on the outside then it's 330ml. OTOH if you load one reel with two rolls you'd need at least 640ml.

Both numbers assume you have the tank level. That the developer is strong enough

If the inside is more developed then the end that was loaded last then the volume was enough. Was the D-76 stock? Or diluted?

I used d-76 at 1:1. I had photographed the sky in a matter of minutes and aimed it in the same direction for all twelve shots. My final guess for this batch of rolls is that I did not consistently agitate. perhaps rolling more in one direction than the other. Later this week I will be posting new images from my second round of tests. thanks to all who replied.

victor

Venchka said:

...
The 2553 will hold approximately 1300+ml without dribbling...

Click to expand...

That is the rub. Don't fret per ml. If you are spinning it by hand, put a full liter in the tank and have at it.

The electric roller base is a good idea and much cheaper than a CPP-2. However, as time goes on I get atavistic with certain darkroom practices so there is something satisfying about manually tending to a spinning drum for 7 minutes. I find that a Jobo roller base in a print tray waterbath is a reasonable facsimile for a CPP-2 and less hassle.