Processing evenness -- medium format

[Sal Santamaura]

I've been developing my own film for 48 years. In that time, the most evenly processed negatives to come out of those efforts were sheet films in Jobo Expert Drums. No matter what method I use (except letting a lab employ its dip-and-dunk system), my 120 results have never achieved the same degree of uniformity, a shortcoming very evident in areas of even tone such as sky.

Jobo now offers a Super 8 Expert Drum kit (shown below) that triggered an idea. Would anyone be interested in a similar item that was designed to process 120 film? Based on a crude mockup, I don't think the outer drum would need to be much larger than Jobo's existing 3006. Please share your thoughts. Thanks in advance.

 

[pentaxuser]

If you or knowledgeable others have the time, can you say what it is about the Expert Drums that ensure this evenness which the conventional 120 Jobo drum and reel does not?

I know we have seen threads recently that have been deliberate challenges. This is not one of those. I am trying to extend my knowledge of what Expert drums do.

Thanks

pentaxuser

 

[Alan9940]

I've developed quite a few 120 rolls of film on my CPP-2 and I've never noticed any type of uneven development with the 2502 reels in 2500 series tanks. I will note, however, that I never load 2 rolls of film onto the same reel; maybe that has something to do with it? I agree that the Expert Drums provide very even development of sheet film--I process both 4x5 and 8x10. However, the BTZS tubes for 8x10 do equally as good a job.

 

[Sal Santamaura]

...can you say what it is about the Expert Drums that ensure this evenness which the conventional 120 Jobo drum and reel does not?...

Jobo's explanation was always that Expert Drums' performance with sheet film is a result of completely random continuous agitation. I have no basis to agree with or dispute that reasoning, only experience with sheet film that empirically demonstrates the result.

I have 120 Jobo reels/drums from both the 1500 and 2500 series, Paterson and Jobo tanks, as well as Kindermann stainless tanks along with Kindermann and Hewes reels. With all that equipment, no matter the protocol followed, be it rotary on a processor, inversion (many, many variations), fill through the light trap, drop loaded reel into developer in the dark, pre-soak or no pre-soak, nothing approaches how even sheet film in an Expert Drum is developed. Only commercial processing in a dip-and-dunk line has achieved similar uniformity for me with 120 film.

Note that this refers to black and white. As far as I can tell, color is a completely separate matter.

 

[pentaxuser]

Thanks Sal. How does Jobo achieve this random continuous agitation? Does random mean that there is a programme that ensures that the number of backward and forward turns alter continuously as opposed to my Jobo CPE2 which has a backward and forward cycle but this is a set number of turns each time or are the back and forth cycles set but some structure within the Expert drum somehow sloshes the developer randomly around the drum?

I am having difficulty getting my head around this.

Thanks

pentaxuser

 

[Sal Santamaura]

...How does Jobo achieve this random continuous agitation? Does random mean that there is a programme that ensures that the number of backward and forward turns alter continuously as opposed to my Jobo CPE2 which has a backward and forward cycle but this is a set number of turns each time or are the back and forth cycles set but some structure within the Expert drum somehow sloshes the developer randomly around the drum?...

There is a set number of turns in each direction; that's not what 'random' refers to. Rather, the hydrodynamics of liquids inside an Expert Drum apparently sets up random flow over each sheet, probably due to movement within and between the chambers. Here's what it looks like:

​

To reiterate, randomness was Jobo's explanation. I'm only vouching for the results, not the mechanism.

 

[RalphLambrecht]

I've developed quite a few 120 rolls of film on my CPP-2 and I've never noticed any type of uneven development with the 2502 reels in 2500 series tanks. I will note, however, that I never load 2 rolls of film onto the same reel; maybe that has something to do with it? I agree that the Expert Drums provide very even development of sheet film--I process both 4x5 and 8x10. However, the BTZS tubes for 8x10 do equally as good a job.

Same here!

 

[pentaxuser]

Thanks Sal I wasn't aware of the video although I have to say that even at slow motion it wasn't clear to me how the liquid's flow was really different to the kind of flow I envisage in a 120 or 35mm Jobo tank but if that is anyone's fault it is mine and not yours.

pentaxuser

 

[Sal Santamaura]

...it wasn't clear to me how the liquid's flow was really different to the kind of flow I envisage in a 120 or 35mm Jobo tank...

Think directed flow around and through the reel, including its core, radial parts and channels. Distinctly non-random.

 

[pentaxuser]

Think directed flow around and through the reel, including its core, radial parts and channels. Distinctly non-random.

Thanks, that explains it well. It wasn't apparent to me this was happening but I can at least see how it works in my mind's eye compared to a reel inside a drum.

pentaxuser

 

[mshchem]

What would be cool is a 3000 series drum with 3 big tubes that you could stuff 3 stacks of 6 1500 series reels. Take 3 liters of developer and develop 36 rolls of 120 at a time. Would need a 3 horse motor. Sorry couldn't resist.. I have never noticed inconsistent development on 120, with any technique I have used. I have used a lot of Xtol 1:1 has a pretty long development time, that doesn't hurt.

 

[Ronald Moravec]

I sent 4x5 E6 to a lab once. Came back all wrinkled. They said it was normal. It does not happen to me at home.

That said, roll film rotation speed needs to be full and reversing unlike expert drum. Use 30 sec full then slow it down and keep bidirectional rotation.

 

[brent8927]

I process by hand in a Patterson canister and haven't run into any problems with unevenness, aside from one time when I just didn't put in enough developer. I develop anywhere from 1-6 rolls at a time (up to 2 per reel). It's possible I just don't have as critical of an eye, but the intermittent agitation/inversion method seems to work well for me. I've never used a Jobo processor, so I really don't know much about how they work.

 

[tokam]

Geez Brent,

You're a brave man! APUG has been alive with agitation threads over the last week.

+1, I'm with you only I have converted to Hewes reels.

Cheers, Martin

 

[Sal Santamaura]

...roll film rotation speed needs to be full and reversing unlike expert drum. Use 30 sec full then slow it down and keep bidirectional rotation.

Tried that and a million other variations. Nothing matches the evenness of sheet film in an Expert Drum.

 

[Loren Sattler]

Sal, I am very interested to know what your agitation technique is for processing 120 film on conventional rolls. I had trouble with uneven development until about 10 years ago when I started vigorous agitation according to Kodak's technical bulletins (5-7 inversions in 5 seconds).

 

[Sal Santamaura]

Sal, I am very interested to know what your agitation technique is for processing 120 film on conventional rolls. I had trouble with uneven development until about 10 years ago when I started vigorous agitation according to Kodak's technical bulletins (5-7 inversions in 5 seconds).

Tried that and a million other variations...

You name it, I've tried it. Basically, every scheme you could find searching APUG and elsewhere, including all film manufacturers' recommended methods.

...Nothing matches the evenness of sheet film in an Expert Drum.

 

[Kawaiithulhu]

Also, the way the expert drum holds each sheet of film almost against the outer diameter while using almost no lip on the edge that runs full width means that there can be no surge between the spokes of a reel, for example.
I think that this would be very difficult to duplicate with an entire roll of 120 without using a tube as long as the film itself, or to corkscrew the holding edge and make loading the thing a nightmare.

 

[removed account4]

hi sal
i have never used a jobo but i bought some of their 1000ml slugs years ago
to store my chemistry in ( now 20 years later one has a pinhole leak ! )
and ... IDK maybe 22 years ago i met some guy who
was living in the ailwife projects in cambridge mass who wanted to sell me
his super graphic AND jobo processor ( it looked similar to the one in the video )
he wanted and arm and leg for each of them so i backed off but always wanted won
ever since. if you make something that can be expertly rolled on the floor of the darkroom sink
better than i novicely roll my own SS tanks i would buy it in a heartbeat. it stinks being low
on quahogs ($) ... maybe someday i can trade in my shoestrings for something worth while !

good luck with you project !
john

 

[ic-racer]

Try using more developer concentrate. Exhaustion leads to un-even development.

 

[Sal Santamaura]

...good luck with you project !...

It's not my project! This was just an idea put out here with the intention that, if a lot of interest was shown, Jobo might think about producing such an item. Not me. I'll stick with sheet film.

 

[Sal Santamaura]

Try using more developer concentrate. Exhaustion leads to un-even development.

Exhaustion has nothing to do with this. I've never used developer other than one-shot with at least as much (usually more) concentrate/stock as the minimum its chemical manufacturer specifies.

 

[ic-racer]

my 120 results have never achieved the same degree of uniformity, a shortcoming very evident in areas of even tone such as sky.....Exhaustion has nothing to do with this

Ok, but fill us in on your results that shows this.

You ask for advice on a contraption to solve a problem for which the reader has no clue.

 

[Sirius Glass]

I have not had uneven development problems with the 1500 series tanks. The only problem I had was overlap two rolls of film on the same reel.