bluechromis
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In this thread, Henning explains why the speed, the speed rated by Agfa (not MACO), of the Aviphot films is much higher than is suitable for pictorial use.I have been reading on this forum in deferent post about the actual speed being (much-) more less than the box speed.
I always wondered why an established photographic film manufacturer (regardless who it is) would be wrong about that, while he's the one who formulated, tested and made that particular emulsion.
I suppose that a (film-) manufacturer would try to commercialise a good performing product; but according to several posts over here, a lot of pushing and pulling needs to be done to reach any satisfying results.
If he is wrong (ore lying) about this, then he is harming his own business and would he do that?
What is really going on?
https://www.photrio.com/forum/threa...-pro-2022-version.194630/page-16#post-2606766
Henning said,
"As I've explained here on photrio in the past Aviphot Pan 200 is designed as an aerial film, and for that purpose it is excellent. It was even used for a very long time by the German military for air reconnaissance with the Tornado jets.
But for us as "photographers on the ground" it is extremely important to know that the light sensitivity / speed rating Agfa is using for their aerial films is significantly different to our standard ISO norm we are using in pictorial photography "on the ground".
Our standard ISO rating is based on Zone I with 0.1 logD density above base fog.
But Agfa is using Zone III for 0.1 logD and sensitivity rating.
Therefore Agfa aerial films are about two stops slower / less light sensitive when you are using normal pictorial standards and classic ISO norm for photos on the ground. And even three stops if you are using Zone System standards with best shadow detail.
The reason for Agfa's different methodology is quite simple:
If you are doing photographs from 2,000m, 3,000m or higher down to the earth, the direction of your photos and the direction of the light are almost identical: You don't have deep shadows and highlights, and you have much less contrast, because of an in general flatter light.
In aerial photography to get good pictures you have to separate the midtones very good, shadows and highlights are much less important.
And that is exactly what Aviphot Pan 200 is doing:
It produces a very pronounced and strong S-shape characteristic curve: Long toe with very little shadow detail up to Zone III, then a steep curve in the midtones with excellent and strong tone separation of these midtones, and in the highlights a flattened curve with quite a lot of highlight detail, but very bad detail tone separation because of the very flat curve."