BW processing

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nickchew

Guest
This is a newbie type question.
If I were to push a TMAX 400 film to 800ASA
How do I calculate the correct timing for the BW processing?
I'm assuming that the time in the developer will have to increase am I right?

(as u can see I'm getting my fingers wet in BW processing.)

Nick
 
Btw, with most developers, for a 1-stop push you multiply the original time by 1.3 to 1.5!

Roman
 
Hey Roman, so what if your pushing two stops? Would you multiply by 1.3/1.5 again? And what of pulling? Is there a table or something that shows this, that would be really handy (and probably better than my guesstimates)!

Thanks,

Scott
 
Tmax 100 and 400 doesn't need to be pulled or pushed, just develope with the same time as if you where doing a normal 400 film. You can download the technical data sheet from Kodak.
 
matu said:
Tmax 100 and 400 doesn't need to be pulled or pushed, just develope with the same time as if you where doing a normal 400 film. You can download the technical data sheet from Kodak.
Click to expand...

Yes. In fact if you were to use TMAX developer the times for pushing up to 3200 are listed on the bottle. In this case, 400/800, 7 minutes at 68F(20C). Here's the Kodak link to TMAX where you can get agitation, stop, and fix recommendations:

http://www.kodak.com/global/en/prof...w/processing.jhtml?id=0.1.18.14.23.28.5&lc=en
 
I know that for TMX/TMAX you can find the various times. I meant the question to be a little more general. Sometimes with the more uncommon film/chemistry combinations it can be hard to find times. I was just wondering if there was some Unifying Mathmatical Constant that was applicable in all/most situations.
 
digitalox said:
Hey Roman, so what if your pushing two stops? Would you multiply by 1.3/1.5 again? And what of pulling? Is there a table or something that shows this, that would be really handy (and probably better than my guesstimates)!

Thanks,

Scott
Click to expand...

Yep, you multiply again (of course those are rough estimates, that you'll have to fine tune for your equipment and style). For pulling you reduce the time by about 20 to 25% per stop; I don't know of any table, though...

Roman
 
Last edited by a moderator:
And remember to multiply the multiply...
i.e. Say your base time is 10 minutes, you want to push the film 2 stops and the multiply factor is 1.5. So for the first pushed stop you go-
10 minutes x 1.5 = 15 minutes
Then for the second stop you multiply the first push again like so-
15 minutes x 1.5 = 22.5 minutes.
Follow?

For the more advanced of us, I'd had good results with changing the temperature rather than the time when it comes to pushing film two stops or more.

Stu :)
 
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