Confused about personal film speed and speed increasing developers.

[John51]

Personal film speed, Zone VI Workshop:

After explaining how to get Zone I exposures, Fred Picker says: Develop these negatives with any developer for your usual or the manufacturers suggested time. The low (dark) values are relatively unaffected by type of developer or developing time, so future changes in developer will not require another test for ASA speed.

I get that, souping for twice as long makes no difference to the shadows as everything that can be developed (Zone I) has already been developed.

What happens if I switch to a speed increasing developer? Zone I now gets less light. How is that enough if choice of developer didn't matter during the test?

 

[Tom Kershaw]

The point of a 'speed increasing' developer is to gain shadow speed / detail. Not sure how the Fred Picker comment makes sense in that context. I don't do 'Zone 1' tests, just spot meter for Z III and development time from there.

 

[Alan9940]

Personally, I've never measured any real speed increase for so called "speed increasing" developers. But, then again, I haven't tried 'em all.

 

[Bill Burk]

What speed increasing developer are you using? What kind of speed gain is it purported to give you? Your speed increase might be a practical speed increase (e.g. pushing). It might be a lower, flatter curve (e.g. POTA). Or it might be a speed gain because of the way you are using the film (e.g., reversal processing). There are lots of ways to make film faster in the sense that you can use a faster shutter speed...

I don’t know any real speed increasing developers off-hand, one which would shift the curve to the left. I am sure there are some but I don’t think they move it very much. Maybe 2/3 stop.

 

[John51]

It's a theory question. I'm confused as to how a developer can be speed increasing if choice of developer for speed testing is irrelevant.

 

[ic-racer]

There are high-speed developers that increase fractional-gradient speeds it is not an urban legend. However, you may lose resolution, increase grain, lose dynamic range or color sensitivity...everything is a compromise. There is no X-axis on the lower chart, but I'd say it would be about 1/3 of a stop difference between HC-110(b) and T-Max (1:4) using fractional-gradient speed determination.

 

[Bill Burk]

Call any developer speed increasing versus the developer used by manufacturer to test for ISO if that developer moves the curve to the left in the vicinity of 0.1 net density above base and fog when the film is otherwise developed to ISO parameters.

 

[Bill Burk]

Likewise if you use any other developer, and develop film to ISO parameters, when that speed point does not reach the rated film speed, then you have a developer which you could fairly call a speed-losing developer. This could happen if the developer was exhausted or otherwise mixed incorrectly. This could be an experimental developer which just doesn't work that well.

A developer which achieves the rated speed would be a full-speed developer.

 

[Bill Burk]

I see what you did there ic-racer!

To get a speed of 526 with that film you had to develop it 30 seconds after exposure!

So yes if you develop a film as soon as humanly possible after exposure, it's possible to get film to give more than an extra stop of speed versus normal rated speed.

Try to imagine what that might look like! Maybe a microfilm or high-speed camera built in conjunction with a developing system that develops the film as soon as it passes the exposing gate.

 

[mshchem]

I found this. Interesting how much technology has changed in roughly 65 years .

Kodak Solution A For
Kodak Special Developer SD-19a

In a previous article, “The Low-
Down on Higher Film Speeds,” in
the Number 1, 1952, Photo Notes,
we discussed the use, advantages,
and limitations of Kodak Special De-
veloper SD-19a for greatly increasing
film speeds. We recommended that
it he used only when severe under-
exposure is absolutely unavoidable.
We have l>een deliberately conserva-
tive in pushing the use of Kodak
SD-19a because its use introduces
some loss in definition, a higher base
fog, and more likelihood of finger-
prints, abrasion marks, etc. I lo waver,
many professional people who must
make pictures in dim light have been
enthusiastic about their results with
this developer. Since the results
please them, they will probably satis-
fy others who find that the most sen-
sitive films still need to he squeezed
a little occasionally.