Jobo multitank 5, 2551greenspun.com : LUSENET : Large format photography : One Thread
Hello, I've recently aquired a Jobo multitank 5 (2551) with two reels for 4X5. My question is, how much developer do I use in this system? As I understand it, you don't fill the tank completely, and the tank rests on its side submerging any one portion of the film at a time. There is a second part to my question. Someone told me, I could use this tank just fine by floating it in water and rotating it myself; however, I don't know how many revolutions per min. I assume you rotate it in one direction for a few rotations, and then you roll it backwards for one. I do not know this for a fact though, which is why I'm asking you. Also, in this type of developing process, does one have to use more time or less time, as it is constant agitation. I would apprecitate any detailed information into this process. Thank you.
-- david clark (email@example.com), November 28, 1999
I use a JOBO tank, though not the model you have. Most JOBO tanks specify the minimum solution needed on the side of the drum. Remember the specified volume is the quantity of solution that will cover the film when the tank is on its side. You'll still need to factor in the quantity of solution needed for the amount of film you're developing, particularly if you're using dilute developer (i.e. 1:3)
You could float it on water and the agitation would be several rotations in one direction then reverse direction. Unless you're very consistent with agitation, you're results will vary. JOBO has a WEB site (I think jobousa.com) and they're very good with answering tech questions via e-mail. I think rotation would be somewhere around 50 to 75 rpm for your tank. You may want to consider a motorized print base (which are fairly inexpensive) to rotate your drum.
If you can keep the temp and agitation consistent, you'll love the results.
-- Pete Caluori (firstname.lastname@example.org), November 29, 1999.
They are at http://www.jobo-usa.com/jobofoto/.
-- Alan Gibson (Alan.Gibson@technologist.com), November 29, 1999.
You may also find the Jobo roller base useful. Its inexpensive (about $ 20 odd) and you roll the tank on it. If you want more control, I think they also provide a motor drive (which runs around $100) - so the motor deals with the agitation and you deal with monitoring temperature and times. With a tempering bath (I think Jobo makes one of these - TBE2 or something but its somewhat pricey - I use an aquarium heater and a deep bath), you should have adequate control. If you have plenty of money, check the Jobo processors. DJ
-- N Dhananjay (email@example.com), November 30, 1999.
I use the tank and reels you have and place them on a Uniroller. With standard developers like TmaxRS (1:9) and Edwal FG7 (1:15) I have found that after doing exposure tests, I can start processing almost any film by reducing the mfg. recommended development time by 10-15%. As for chmistry amount, I use 800 ml of chemistry plus water for two reels and 600ml for a single reel. Thus far I have very even results, no surging , etc. Jobo person told me that if I was doing only B/W that this uniroller plus drum system should be ok.
-- bob Moulton (Bmoulton@icc.cc.il.us), December 08, 1999.