So I guess you can push film when using BTTB developer.

[rpavich]

So I took the advice of a few folks here and did my test. I wanted to know if it was possible to push film using Barry Thornton's Two Bath Developer.

I loaded a very short roll and just took a repetitive shot while sitting at a red light. After each shot I just raised the shutter speed one full stop. The first neg is metered at EI 200 and from then on it's just clicks, no re-metering.

The most dense neg is at EI 200 and the next one is EI 400 and so on.

The directions say 5 minutes for EI 400 film so I just added 25% to it making it 6.25m (I rounded it to 6m 30s.)
I must say that I'm pleased. The negs are dense all the way until EI 3200, and there was detail in the shadows to 800, and even at 3200 it's a very usable negative for sure.
At this dev time I like the 800 the best but all I was really aiming for was to see if I would end up with a bunch of very underexposed/thin negatives.

This is a document scan of the negs for reference. I'm thinking of doing a contact sheet also.

 

[ic-racer]

Make your best projection print from each and compare to see which is best. That is the gold standard for the ASA and ISO standards; the minimum negative exposure for the first excellent print. Sensitometry and densitometry have a role when one does not have the time to make and compare all the prints.

 

[rpavich]

Make your best projection print from each and compare to see which is best. That is the gold standard for the ASA and ISO standards; the minimum negative exposure for the first excellent print. Sensitometry and densitometry have a role when one does not have the time to make and compare all the prints.

That sounds like a plan. Now, to make sure I understand. Minimum exposure is what minimum time is needed to just get the clear part of the negative edge to hit DMIN...right?

 

[rpavich]

So i did what you said...what an eye opener!
I would have never guessed that 1600 would be the best. 800 was very close but lacking in much contrast; just a bit too light. It appears that the best best is just between 800 and 1600, something like 1250 or so.

What was really surprising was that 3200 was not bad at all.

Very interesting.

I first made a test strip to find DMIN and it turned out to be 11 seconds. Then I printed them all at 11 seconds using each successive negative.

 

[John Wiegerink]

I'm guessing this is Tri-X? How did the grain look at ISO 3200?

 

[rpavich]

I'm guessing this is Tri-X? How did the grain look at ISO 3200?

This is HP-5, and the grain was minimal, very nice