Calculating mega-push development times

pentaxuser · Apr 7, 2021

Autonerd said:
Wanted to try pushing FP4+ four stops tp 3200 just to see what it would look like. (I know it probably won't look good, but I was in a discussion on another forum and we thought it might be fun to try.) How can I calculate the development time for a push like that? Data sheet only goes up to 400 and MDC to 800.

TIA
Aaron

I thought that the OP above made it very plain about (a) where he is coming from and (b) what is likely to be the outcome. Having told us the where and what, all we need to do is either ignore his thread or provide the best advice as to what he might do to try and achieve this.

pentaxuser

M Carter · Apr 9, 2021

Paul Howell said:
Works well for finding the personal E.I for your equipment and taste, a 4 stop push is not going to show a gray scale, no shadows, just highlights. As a working PJ in the 70s and 80s I on rare occasion pushed Trix to 3200 and even 6400 in order to get shot where flash would now work or not allowed, you get a result, not all that pleasant. The 50% rule came from UPI's darkroom boss.

I still test anything like this - even with that extreme of a push, the goal (for me anyway) is to get highlights placed "normally", as if I hadn't pushed at all. While 4 stops is extreme, you'll still get some mids and upper mids, the only way I know to find the dev time to optimize what image actually can make it to my final output (for me, prints, for others, scans) is do a test, in a developer that will hold shadows as much as possible.

Bill Burk · Apr 9, 2021

Given what I know now, I would develop the film in D-76 stock for 64 minutes at 68-degrees F

I would put a sensitometry strip on the roll and determine effective speed by Delta-X

But anybody can go out to a standard outdoor open shade scene and run through their f/stops and shutter speeds from 1/2000 f/16 on down...

Come back and see what pictures looked the best.

Then go out and play with the next roll at the EI that gave the best results on the test roll.

With one roll of film you will find an interesting result that can become your personal EI for that film (when you want the fastest speed possible).

Maris · Apr 9, 2021

I tried a mega-push on Tri-X years ago, wanted an EI of 3200, and found that developing time became irrelevant beyond a certain point.
Stand development in full strength Dektol for 12 hours, 24 hours, and 36 hours yielded the same amount of image detail. Once all the exposed silver halide crystals became developed there was nothing new that the developer could act on. What actually happened was the developer started reducing the unexposed silver halide crystals producing base fog. Given a sufficiently long developing time the base fog would chase the exposed bits and the film would end up dark and effectively unenhanced

Bisco · Apr 30, 2021

When you are pushing 4+ stops everything becomes very subjective in terms of development like has been stated a couple times in this thread but I read this article and found it helpful to get a base time for "mega-pushes" that you cant find information on otherwise: Appendix A of the Technical Field Guide for the Discerning Analog Photographer: push/pull processing calculations | EMULSIVE. The formula isnt complicated and the multiplication factors for the new dev times are the same for any film being pushed the same number of stops so I just made a small chart of the factors from 1-10 stop pushes. I recently had success pushing Across100 to 6400 and could have likely gone farther

removed account4 · Apr 30, 2021

Autonerd said:
Wanted to try pushing FP4+ four stops tp 3200 just to see what it would look like. (I know it probably won't look good, but I was in a discussion on another forum and we thought it might be fun to try.) How can I calculate the development time for a push like that? Data sheet only goes up to 400 and MDC to 800.

TIA
Aaron

Aaron
what developer do you plan on using?

Juan Valdenebro · May 1, 2021

For sure the OP wants any superpush as well done as possible, even with a negative that's blank below the gray card. With well done I mean with the highlights well placed.
The best developer I know for that, is Microphen. When light is soft, it produces great contrasty tone, and when there's high contrast, it controls highlights as much as it is possible.
He can do what he wants: FP4+ @ 3200, Microphen Stock 20C, 15 minutes, 4 inversions in the beginning and 4 inversions every minute.
He'll see big grain, blank shadows, and enhanced contrast in the upper grays: nothing new.

Christiaan Phleger · May 1, 2021

The very best extreme push (other than hydrogen peroxide vapors post development/ pre-fix) developer is UFG. Track down an auction for a can and try, Acufine is close as well but the real deal is UFG.

Calculating mega-push development times

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