Bergger PMK Roto Additive

[Tim V]

Hi all,

Anyone know what Bergger PMK Roto Additive is? I'm assuming that it's an antioxidant of some sort, buy anyone know what and how it'll effect film development times etc. when used in the Jobo?

From the Bergger literature, per Linhof Studio's website:

"The Bergger PMK Roto Additive was formulated in order to allow the use of the PMK in the Jobo-type rotative machines. It may be used between 1+50 and 1+100, and must be added to your PMK working solution. Developing times given on the PMK datasheet can be used, but they are only a starting point. You will certainly have to adapt them in order to reach the result you expect."

I'm going to try it with a box of Pancro 400 to see how I like PMK in the Jobo vs Pyrocat-HD mixed 2:2:100. I'll certainly need to still split the developer stage into to 1L baths, but just wonder how much more active it might make the developer and hence what time differences to expect.

Any info / guidance / user experience appreciated!

Thanks,

Tim

PS: I've also asked this question on the Large Format User Forum, as I'm an 8x10" sheet film shooter.

 

[DREW WILEY]

Try a different pyro formula designed for rotary. Jobo has an awfully high RPM and PMK tends to get overdeveloped. Or you could displace the oxygen with argon. Some people totally fill the drum with no air space left, but that's quite wasteful of chem. Or you could just gently roll your drum back and forth on the bed of your sink by hand instead of using the machine.

 

[Sirius Glass]

I am using Pyrocat HD in Glycol with the Jobo processor. It is supposed to have a long life. My only problem is figuring out processing times for Tri-X 400 120 and Delta 3200 120 exposed a 3200. I am using the 'P' speed. It is one of four pyros offered by Photographers' Formulary for Jobo processors.

 

[DREW WILEY]

I'm a bit skeptical that you can truly get full box speed with Delta 3200 using pyro without sacrificing some shadow gradation. But Pyrocat HD in glycol is a better rotary option than PMK.

 

[Sirius Glass]

I am using Pyrocat HD in Glycol with the Jobo processor. It is supposed to have a long life. My only problem is figuring out processing times for Tri-X 400 120 and Delta 3200 120 exposed a 3200. I am using the 'P' speed. It is one of four pyros offered by Photographers' Formulary for Jobo processors.

I'm a bit skeptical that you can truly get full box speed with Delta 3200 using pyro without sacrificing some shadow gradation. But Pyrocat HD in glycol is a better rotary option than PMK.

I have not figured out the replenished XTOL time in the Jobo processor for Delta 3200 either, but it would be great if I had an ISO 3200 film in 120 for wildlife photographs using the 500mm lens or the 500mm lens with the 2XE extender.

 

[Tom Kershaw]

I have not figured out the replenished XTOL time in the Jobo processor for Delta 3200 either, but it would be great if I had an ISO 3200 film in 120 for wildlife photographs using the 500mm lens or the 500mm lens with the 2XE extender.

I think I've made this comment in another thread but I'd be tempted to just use DD-X or ID-68 / Microphen for Delta 3200 as the results seem to come straight away, rather than the frustrating experience with XTOL.

 

[DREW WILEY]

TMY400 shot at 800 will give you much greater sharpness than Delta 3200, and way better than TMZ, which is really 1000 speed according to the tech sheet. Faster and you're just lopping off shadows. I don't know if they make it in 120 size yet. Delta 3200 is a more forgiving film in terms of exposure due to the long toe. Nice on rainy days. Has its own look. I haven't tried if for wildlife per se. I have 300 mm lenses for my Pentax 6x7. When I want more reach than that, I'll put a Nikon body in same the kit, and a lens mount adapter. I never got along well with teleconverters.