why shoot at a different ASA than the film is rated for?

venchka said:
Roger,
#1: Pushing in your post is inaccurate.
"expose for the shadows, develop for the highlights"
http://www.apug.org/forum/index.php...ows-develop-of-the-highlights-meaning.110318/
N-, N, N+ development.
Ansel Adams explained it best in The Negative.
https://www.amazon.com/Negative-Ansel-Adams-Photography-Book/dp/0821221868
Or mix different films in the same tank.
http://www.tmax100.com/photo/pdf/devforscan.pdf
. . .
Click to expand...
Dear Wayne,

You are of course quite right. OVER-developing. Shows how carefully most people (including ourselves) read our posts. Edited and corrected!

Sorry!

R.
 
I make photographs with film rated at "box" speed.

To me it would be confusing, oops gotta develop at this time because I exposed the film at this speed. When I bulk load some 35mm film into cassettes, using a Sharpie pen, on the leader I put type of film, like Pan F and the number of exposures I can make and the date I loaded the film into the cassette.

There is enough other variables I can play around with, different developers, dilutions, stand development, temps, water source to name a few.

And on and on.

I tend to spend my time with other ingredients when I make photographs.
 
When I used to shoot Ilford XP2 which was my favorite black and white film I almost always shot it at speeds different from its rated speed of ISO 400. This is a C41 film and had the advantage that you could shoot every single shot in the roll at a different speed if you wished - or so I was informed although I never did this myself. Instead I shot it at ISO 200 because that speed provided a lovely "buttery" soft film grain that produced beautiful images - significantly better than the more grainy images shot at ISO 400.
 
For me my black and white standard is expired (and stored frozen) ISO 400 film for speed cameras. The package information includes a range of developing up to ISO 3200 - which I often use. There are costs - an increase in contrast is the issue - no "buttery smooth" here but the grain is still fine.Why do it? You can shoot in near blackness. It's not the "right" solution for every situation, but it's a reasonable solution for me. Most films, however, don't like pushing that far.

Film is a kind of art medium. You can use it as you want - even backwards. You can push or pull to achieve certain goals. You may use particular development chemicals which naturally alter the film sensitivity in B&W, increase or decrease grain.

Broadly speaking, pulling film (using at a lowered rating) reduces contrast allowing a wider span of brightness to be reflected on the film - this is then expanded out again in printing (potentially). Alternatively the film may be pushed (used as a higher rated film) and overdeveloped which increases contrast and narrows the span of original brightness expressed on the film.
 
tons of reasons as mentioned above. I don't have an ax to grind but don't think Ilford's films are truly as fast as they say. I get much better results at half the recommended speed.
 
Hatchetman said:
tons of reasons as mentioned above. I don't have an ax to grind but don't think Ilford's films are truly as fast as they say. I get much better results at half the recommended speed.
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That's only because you don't understand what ISO means. Is it the perfect speed for everyone? No. Is it standardized? Yes.

Almost 60 years ago, nominal ASA film speeds for B+W negative films pretty much doubled overnight, because the previous "safety factor" was removed. And guess what? In the late 1950s, people who didn't understand ASA speeds were saying that films were "really" faster than marked.

If you want to understand more about film speed, read this.

Cheers,

R.
 
Thanks for the confirmation Roger:

The choice of developer is important. A speed increasing developer can give two-thirds of a stop increase in true ISO speed, or possibly even a little more, so a film that is ISO 400 in a 'middle of the road' developer such as Kodak D-76 may well be ISO 650 or even faster in something like Ilford Microphen. In the opposite direction, there is virtually no limit to the speed that can be wiped off by a fine grain developer, but two thirds of a stop would be quite usual. In other words, the same ISO 400 film could fall to ISO 250 in something like Ilford Perceptol.

Most film manufacturers use middle-of-the-road developers for film speed testing, but ISO rules allow the use of any stated developer. The most egregious examples are Fomapan 200 and Paterson Acupan 200, where ISO 200 is reached only in speed-increasing developers: in D-76 or similar, ISO 125 is a lot more realistic, or maybe ISO 160 in most of the Paterson developer line-up except the extreme speed-increasing developers.
 
Hatchetman said:
Thanks for the confirmation Roger:

The choice of developer is important. A speed increasing developer can give two-thirds of a stop increase in true ISO speed, or possibly even a little more, so a film that is ISO 400 in a 'middle of the road' developer such as Kodak D-76 may well be ISO 650 or even faster in something like Ilford Microphen. In the opposite direction, there is virtually no limit to the speed that can be wiped off by a fine grain developer, but two thirds of a stop would be quite usual. In other words, the same ISO 400 film could fall to ISO 250 in something like Ilford Perceptol.

Most film manufacturers use middle-of-the-road developers for film speed testing, but ISO rules allow the use of any stated developer. The most egregious examples are Fomapan 200 and Paterson Acupan 200, where ISO 200 is reached only in speed-increasing developers: in D-76 or similar, ISO 125 is a lot more realistic, or maybe ISO 160 in most of the Paterson developer line-up except the extreme speed-increasing developers.
Click to expand...
You're welcome. The magic word is "standardized". ISO speeds aren't perfect but they're a lot better than letting the marketing department pluck a figure out of the air, even if the marketing department does sometimes insist on using a speed increasing developer.

Ilford and Kodak figures are a lot closer to true ISO speeds in a middle of the road developer. But as I say, "true ISO" won't always give you the results you like best.

Cheers,

R.
 
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