Comparative speeds of medium speed films
I am wondering about the comparative speeds of medium speed films (~100-125 iso).
(Have I missed anything?)
I am not asking about the absolute speeds (e.g. is TMAX 100 really 100 iso?) What I want to know is the relative speeds (e.g. Fomapan 100 is half the speed of FP4+, or whatever.) Any comments? Just for sake of argument how about if we peg everything to one or two films, such as FP4+ and TMAX 100.
Of the ones on your list I am familiar with FP4, Tmax, Plus X and Acros. I think the differences are pretty minimal matched with the right developer. The bigger difference comes with long exposures. The more modern emulsions have much better reciprocity characteristics. I am fond of Acros because I don't even need to think about reciprocity.
The speeds depends on the developer you use. Tmax 100, for example is 100 in D76 1:1, and 50 in Rodinal 1:50. FP-4 Plus is 100 in both Rodinal and D76 in my experience.
I hate to repeat it again, but it's not because TMAX 100 is better at EI 80 when you develop it in coffee and alka-seltzer that it means it's not an ISO 100 film.
Being ISO 100 means only that under ISO circumstances (which are extremely well controlled and VERY different from any real world photo situation), the film speed point will be 100.
So again, the "relative" speed of ISO 100 films to each other is a moot point: they're all ISO 100 under ISO circumstances.
There are much more important differences between those films than speed.
First, there is spectral sensitivity. B&W films react differently to colour, and some films will render a yellow more light than other ones.
Second is characteristic curve. Most mid-speed films tend to have a rather straight curve, but there can be minute variations in either the shadows, midtones, or the highlights.
Finally, grain type (modern v. traditional) has an influence on the look and the perceived graininess and apparent sharpness.
Neopan 100 is actually Fuji Neopan Acros 100 - same film.
I've used virtually all those films over the years except perhaps Plus-X, I can't remember using it.
As Chris says the speed is partially dependant on what developer you use, but if you choose one and test all those films you would find that you would need to us a different EI to get negatives that were comparible and printed similarly on the same grade of paper, tonal range & contrast etc.
You missed one very important 100 ISO film - Agfapan APX 100, there's plenty of 35mm still available and Fotoimpex will re-introduce it in the next year or so.
To me the best 100 ISO film has always been APX100 by a long way, it gave great tones, sharpnes & fine grain at 100 EI in all formats,. I only stopped using it when they stopped making LF films. Using APX 100 as a comparison.
APX100 - 100 EI
FP4 - 80 EI
Tmax 100 - 50 EI
Fomapan 100 32-50 EI
Neopan Acros 100 -80 EI
Delta 100 - 64 EI
EFKE 100 can't remember as I settled on using EFKE 25 - 50 EI back in the 70's.
One observation I'd make is that the dev times to get the same contrast at the EI's I've listed are remarkably close with one exception - Fomapan 100 (also 200) need about 2/3'ds the dev time to get similar tones/contrast.
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