Same film type - difference between roll films and KB?

william5 · 2006-05-23T20:12:36+00:00

Bei gleichem Filmtyp, hier ein ADOX CHS 100, stelle ich bei gleicher Belichtung und gleicher Entwicklung deutliche Unterschiede im Kontrast fest. Nach meinem...

william5

Using the same type of film – in this case, ADOX CHS 100 – I’ve noticed significant differences in contrast despite using the same exposure and development settings. Based on my previous understanding, I actually expected similar results. However, the 35mm film exhibits a greater gradient than the roll film. There is another difference, though this probably has more to do with the base material: when pre-wetting the roll film, the anti-halation layer is washed out (the water becomes heavily discoloured). With the sheet film, pre-wetting produces no visible result, at least. Can anyone explain these differences to me in a way that makes sense? Thanks, Jens

SamuliSchielke

The differences in contrast are simply variations between different production batches. The roll film and 35mm film probably don’t come from the same batch, and different production batches are never completely identical – not even at Kodak, and certainly not at Fotokemika. Usually this isn’t a problem, as the differences are small enough not to affect image quality. If the highest precision is required (commercial commissions and the like), or if you’re a bit of a techie, you’ll just have to test the film beforehand. The antihalation coating is applied differently on roll film and 35mm film. Others know exactly what the difference is; I don’t. Regards, Samuli

Gast

Somewhat related to the topic: discussion thread on APUG

william5

No, I’d rule out the possibility that these are simply variations between production batches. The differences are far too obvious, far too distinct for that. Besides, I noticed this last year as well. And since I’ve bought new materials in the meantime, I don’t think the batch theory holds water either.

huehnerhose

Hi! Do you develop your films using the tilt method or the rotation method? If you use the rotation method, could it be that you’re using too little developer solution with the roll films, causing them to be underdeveloped and resulting in a softer image? (Although streaking might/should occur in that case too) Or: Do you simply expose them differently as a rule? If the roll films are slightly underexposed, they should also come out a bit softer... Or they might be overexposed... Have you ever cross-checked with other film types? Regards Sebastian

william5

Hi! Do you develop your films using the tilt method or the rotation method? If you use the rotation method, could it be that you’re using too little developer solution with the roll films, causing them to be underdeveloped and resulting in a softer image? (Although streaking might/should occur in that case) Or: Do you simply expose them differently as a rule? If the roll films are slightly underexposed, they should also come out a bit softer... Or they might be pre-exposed... Have you ever cross-checked with other film types? Regards Sebastian

Hi Sebastian, I use tilt development. And to save time, I’ve also developed KB and roll film together in one canister. The films themselves come out cleanly developed afterwards. So no fog or anything like that. The question about exposure just got me thinking, because it could be that the shutter speeds on the respective cameras aren’t correct. The 35mm film is exposed with a Nikon F80, the roll films run through a Kiev. And their exposure times aren’t correct. But... that theory doesn’t hold up. Because I also noticed it with films exposed in a Hasselblad using three different lenses (i.e. three different shutters). I haven’t checked other film types. Perhaps I should do that sometime. Regards, Jens