Arista C41 Rotary: Dumb Question for Jobo

JWMster · Apr 29, 2018

So I am about to embark on my 1st color negative processing and made up my chems tonight for tomorrow night's processing. I'm aiming at the 85F temp time - which isn't really material to my question, but just what it is, and the reference to "Rotary Tube" processing times is "For use with Unicolor type film drum". So can I simply use this with my Jobo? I've done lots of B&W but never color, so while I expect, "DUH. Of course!", with B&W there are many who use the regular hand dunk times with a Jobo. So coming from that reference point, perhaps it isn't so boneheaded... though I'm sure it is. Appreciate the whack to the head, "Duh!" Thanks!

Photo Engineer · Apr 29, 2018

Color film is designed to be processed at 100F, PERIOD. Any other temperature is chancy at best.

PE

btaylor · Apr 30, 2018

After you get your chems up to temp use the Unicolor film drum times for your Jobo. The time specified is for continuous agitation whether on a Unicolor roller or a Jobo.

JWMster · Apr 30, 2018

Okay that's all great! Thanks! both for the Time AND Temp clarifications.
One follow-up: Arista recommends a 1 minute pre-soak and Tetenal a 5 minute pre-soak. I think the Jobo standard (for B&W at least) tends to run 5 minutes. Ditto for Tinsley's comments on C41.Thoughts? Experience?

BMbikerider · Apr 30, 2018

Photo Engineer said:
Color film is designed to be processed at 100F, PERIOD. Any other temperature is chancy at best.

PE

Oh yes I totally agree.

BMbikerider · Apr 30, 2018

The drum AKA tank to be used with a JOBO should have the drive for the tank in the form of a gear wheel so that the rotary action is automatically changed. The same applies with the alternative motor drive and that is via a magnet attached to the base of the tank and the drive spindle on the end of the motor. I am not aware if the Unicolor drum/tank can be successfully adapted to work with ether method.

I personally do not have a dedicated pre-warming stage. Instead, as soon as the water bath is filled and the temperature setting made, I float the tank containing the undeveloped film in the bath until the developer is up the the 38c level. You will have to tilt the tank (35mm) to begin with so that air trapped by the magnet recess is released. That way the temperature rise is gradual and will also raise the temp level to the cap which is not under water.

I have been doing it this way since 1991 and it has served me quite well with no failures attributable to anything else except 'operator error'!

JWMster · Apr 30, 2018

BMKbiker: Yes, I use Jobo 2500 and 1500 tanks. Prefer the 2500 for 120 as the reel flanges are wider for 120. Given a 600ml limit on my small(er) Jobo, the tank generally rides clear of the water bath, but the time is generally short enough that the initial temp of the developer at the start of the 3.5 minutes changes insufficiently to be a problem according to many of the C41 posts I've followed. I guess if your non-presoak is working, that's good. I usually go by-the-book for round one in many things. But your testimony attests to the fact that the process is more robust than we tend to believe. And that's a VERY GOOD thing. Thank you!

As to Pre-Soak, I'm inclined to go with Tinsely's JOBO book advice where the 5-minute pre-soak is the standard. I've used this with very, very pleasing results in B&W and Ilford's ID-11, and if Tetenal recommends the same (which it does) and it's affirmed by Tinsley,it seems the path of least resistance. It's only Arista's instructions that say 1 minute that gives some pause.

AgX · Apr 30, 2018

JWMster said:
Okay that's all great! Thanks! both for the Time AND Temp clarifications.
One follow-up: Arista recommends a 1 minute pre-soak and Tetenal a 5 minute pre-soak. I think the Jobo standard (for B&W at least) tends to run 5 minutes. Ditto for Tinsley's comments on C41.Thoughts? Experience?

This is the first time ever I hear about Tetenal advising a presoak.
Either you or your source for the manual must have got something wrong. And yes, I got the original manual at hand.

The presoak is a american concept anyway.

JWMster · Apr 30, 2018

Ah... thank you for catching that! I looked at the Tetenal instructions online at Freestyle, and while a different edition from those I have at home, you're likely right that I've let my eyeballs elide over this and misread it. Arista's C41 instructions at Freestyle are exactly the edition I have at home and they do call for a pre-soak of 1 minute. FWIW, I don't really know what "Preheat" means as I don't typically fill my Jobo water bath level that high (I fill the bath with roughly 6 liters). Maybe I've been doing that wrong, but haven't had any problems with B&W chemistry, and a level at shoulder height to the chemistry bottles allows easy management of the developer temp. I could see putting the tank into a separate bath to "pre-heat"....but perhaps it will fit somehow at the end of the raised bed in the bath. What do folks actually do here?

I also note reference to using a Stop Bath when employing used BLIX to "increase reliability". I'd missed this, too.

AgX · Apr 30, 2018

Preheat at Tetenal means immersing the inversion tank in the tempering bath, resp. let the rotating tank rotate in there, for 5 minutes. Thus the film itself stays dry at this stage.

JWMster · Apr 30, 2018

Yes, I'm sure that's it. The trick is to figure out how to get a 2500 tank immersed without floating the other chemical containers out of the tub.

AgX · Apr 30, 2018

As you are having it on rotation, how could the yet empty processing tank drive the bottles out of the tempering bath, when it does not even do so when rotating in the fillled state?

JWMster · Apr 30, 2018

Thanks, but I don't think you really mean to immerse yourself in detail. Nevertheless, if you're familiar with the Jobo CPE2+ that I'm using, you'll know that the rotation assembly sits on a bed which is raised about 3 inches (I have NOT measured it, but that's my visual memory here at work) above the base of the water bath. The chemistry bottles sit within the lower part. To raise the water level sufficient to soak the rotating tank in my unit, requires at least 2 to 3 liters more water. If the bottles are filled with 600ml each, they don't rise. But if you do 2 films and use 300ML - which is what I generally do with B&W, then the bottles are more than half full of air and tend to float. If you want to monitor the temperature, the developer bottle cap is off. I don't have weights on my tanks, 'cause Catlabs tells me they're not needed. And they're not... at least for B&W.

Photo Engineer · Apr 30, 2018

I use a 1 minute presoak for ALL C41 processing.

PE

BMbikerider · Apr 30, 2018

JWMster said:
BMKbiker: Yes, I use Jobo 2500 and 1500 tanks. Prefer the 2500 for 120 as the reel flanges are wider for 120. Given a 600ml limit on my small(er) Jobo, the tank generally rides clear of the water bath, but the time is generally short enough that the initial temp of the developer at the start of the 3.5 minutes changes insufficiently to be a problem according to many of the C41 posts I've followed. I guess if your non-presoak is working, that's good. I usually go by-the-book for round one in many things. But your testimony attests to the fact that the process is more robust than we tend to believe. And that's a VERY GOOD thing. Thank you!

As to Pre-Soak, I'm inclined to go with Tinsely's JOBO book advice where the 5-minute pre-soak is the standard. I've used this with very, very pleasing results in B&W and Ilford's ID-11, and if Tetenal recommends the same (which it does) and it's affirmed by Tinsley,it seems the path of least resistance. It's only Arista's instructions that say 1 minute that gives some pause.

It also helps when the water out of the tap where I live is around 15c in the summer and even less in the winter, this gives it a long while to gradually heat up and transfer the water temperature to the tank so it remains quite stable. I fill the JOBO up to within 3/4" of the top of the water bath container and this is about 1/3rd the way up the tank when it is rotating so there is very little fluctuation over the 3min 15 sec dev time.

JWMster · May 2, 2018

Thanks guys! First two rolls came out great. Did raise the water level as someone mentioned ...up near the top and ran the 5 minute pre-heat. I thought about a pre-soak of 1 minute, but decided against it on round one after reading Tinsley say and a few articles in the Jobo archives that a pre-soak lowered the dependability of results. Not in a position to judge, I figured if it didn't work without it on round one, I could go there on round two. I'm currently scanning some shots from a roll run through my Zeiss Ikon Super Ikonta III... which while it ain't the shapest knife in the light bulb drawer, still turns in some good shots. Wanted to see how Portra 400 would do home developed, and the verdict looks like this is certainly good enough for everyday use. I couldn't say whether the results are good enough from a Pro's perspective for commercial work (I doubt it), but for what I want in an everyday way... it looks fine. Trick will lie in the level of consistency and dependability as to whether I'd use it myself on really important stuff - given I've a good lab up the street. But for this everyday stuff... it'll do very well. Likely experience will have a lot to do with whether I want to use it for travel shots where I can't go back out and reshoot.

Arista C41 Rotary: Dumb Question for Jobo

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