Bend gamma

Ewald · 2013-07-14T03:00:47+00:00

Hi friends Ich teste gerade den Planfilm Acros 100 densitometrisch ein.(Stouffer-Graukeil)? Allerdings mit Laborbeli,(Ilford EM 10) aber das geht ja wie ich...

Ewald

Hi friends I’m currently testing the Acros 100 sheet film using a densitometer (Stouffer grey scale). I’m using a lab-grade developer (Ilford EM 10), but that works, as I’ve already found with a few other film-developer combinations. ? However, with the Acros 100, where my tests only yield 50 ASA, I can’t get the gamma above 0.38. (ADOX 49 developer, dilution 1+1, 18 mins agitation) Question: could it be that the film cannot be developed at a steeper curve, or would a different developer be needed? Or do I need to extend the development time beyond 30 minutes? ? I’m still a novice when it comes to densitometry. ? Regards Ewald

piu58

The developer might be exhausted; I’d start by adding more developer. And next, I’d use undiluted A49.

Ewald

It could be that the developer has run out of potency; I’d start by adding more developer. And next, I’d use undiluted A49.

? Hi, piu The developer has just been prepared from powder. Using the same dilution and processing time, I’ve already been able to develop Ilford Delta 100 roll film without any problems to a gamma of 0.65. The 300 ml volume for agitation is plenty for a single sheet and is only used once. The lab meter also shows exactly one stop difference from one blackening zone to the next. A test shot under the same processing conditions produced a negative that was actually flawless. Anyone else have any ideas?? Regards Ewald

Ewald

I came up with the idea myself. Although the ILFORD EM 10 lab meter has a scale of 100 units, it is essentially just a light meter for various brightness levels and is completely unsuitable for densitometry. But that isn’t stated on it. A comparison with my somewhat primitive Kaiser automatic timer with an attached sensor led me to realise today that my extended development time was too long (gamma 0.9) and the adjusted ISO value was also incorrect. The values previously determined with 35mm film can therefore also be applied to sheet film. greetinx Ewald