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H&D curves of different films
"Jytzel" wrote in message om... "Richard Knoppow" wrote in message nk.net... "Martin Jangowski" wrote in message ... In rec.photo.darkroom Jytzel wrote: I'd appreciate if somebody can comment on the characteristics curves of the following films: APX 100 APX 400 FP4 125 Pan F plus 50 HP5 400 Acros Delta 400 What characteristic curves? Every developer and every development time will give different curves... Martin The developer will have some effect on the curve but its mainly determined by the distribution of sensitivity of the silver halide particals in the emulsion. This is turn is controlled by the exact method by which the emulsion is made. Two extremes are the recently discontinued Plus-X Pan sheet film compared to T-Max 100. Plus-X Pan sheet film (the roll film is different)has a curve which is constantly swept upward. In other words the contrast increases continuously with density. T-Max 100, OTHO, has a fairly straight characteristic. The two will be different regardless of the developer used although some will give a slightly straighter curve with both than others. The difference results in a difference in the tonal rendition. When the same shadow and highlight points are chosen the upswept type film will reproduce mid-gray tones darker than the straight line film. Kodak intended this to be used for studio photography where it was desired to exagerate highlights. Tri-X sheet film is similar to Plus-X but not quite so steeply rising. You will find a number of characteristic curves for popular films in several developers at: http://www.fotoimport.no/pg02/PG02-1-1.htm#tab Most of these look reasonably correct. The site is in Norwegian but one can navigate it pretty well. -- Thanks Richard, I know about tri-x, PX and TMX, but what about Verichrome pan? To my eye it seems that it has an upsept curve to a certain degree (I tried it with D-76, HC110, DK-50, and Rodinal) It was my favourite film. So bad it was discontinued. I'm looking for a replacement (PX is not an option). HP4+ seems to have an S-shaped curve. APX 100 seems to have a unique curve - long toe round shoulder (?)- I'm not sure. Can anybody help me interpret them? V-Pan was also a favorite of mine. I finished off the two bricks I had and haven't seen any more. Probably the closest is Plus-X Pan roll film. This has a similar (but not identical) sort of curve and is also a very fine grain relativly high resolution film. I think it gets short shrift because people think its the same as the now discontinued Plus-X sheet film. Its a very different emulsion. APX-100 is very good film but grainier than Plus-X. FP-4 is also similar but has somewhat different tonal rendition. Kodak's published curves are pretty reliable. Agfa and Ilford tend to publish idealized curves which makes them harder to compare. About the only way to really tell how a film responds tonaly is to try some. As pointed out elswhere in this thread developers have some, but not a lot, of effect on curve shape, with the exception of compensating developers, which create a shoulder. i.e., they reduce the contrast of the highlights. This is sometimes desirable but can also result in rather distorted tonal rendition. -- Richard Knoppow Los Angeles, CA, USA |
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H&D curves of different films
"Richard Knoppow" wrote in message news:fk3db.4510
V-Pan was also a favorite of mine. I finished off the two bricks I had and haven't seen any more. Probably the closest is Plus-X Pan roll film. This has a similar (but not identical) sort of curve and is also a very fine grain relativly high resolution film. I think it gets short shrift because people think its the same as the now discontinued Plus-X sheet film. Its a very different emulsion. APX-100 is very good film but grainier than Plus-X. FP-4 is also similar but has somewhat different tonal rendition. Kodak's published curves are pretty reliable. Agfa and Ilford tend to publish idealized curves which makes them harder to compare. About the only way to really tell how a film responds tonaly is to try some. Richard, What do you mean by "different"? |
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