Lee L
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- Nov 17, 2004
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I managed to find some time to run a quick and dirty test with Agfa Rodinal and Calbe R09, using Efke KB25. I decided that running both developers at identical times and dilutions would be the best way to reveal different levels of activity. I have always preferred slow films in a 1:100 dilution of Rodinal, so I stuck with that for this test.
I shot half a roll at EI 25 and processed it in Rodinal and then shot the second half of the same roll and processed in R09. I shot with a Bessa R3A and 75mm Color Skopar at middle apertures and in auto-exposure mode through an ExpoDisc (diffuser), and adjusted the film speed setting to get exposures for Zones I, V, and VIII. Both halves of the film were developed in 300ml water (I use local spring water that I've found to be good for developing) with 3ml of developer concentrate, and both at a time of 12 minutes. Agitation was constant for the first 45 seconds, then two torus inversions and a rap and quarter twist on the bench once each 3 minutes. They were developed at ambient temperature in the darkroom, about 74 degrees.
I measured negative density with a diffuse light above a Gossen Luna Pro F and enlarging attachment, with the negative center covering the enlarger attachment aperture. The Luna Pro F has 1/3 stop (0.1 log density) markings that are spaced enough for reasonable interpolation to about 1/12 stop. (I know this assumes linear response, but it's what I have to work with.)
I found that the Rodinal gave slightly higher density, a bit less than 1/6th stop, and slightly higher gamma, .605 for R09 and .619 for Rodinal. With the Rodinal and this processing routine, EI 25 looks like a good place to start with KB25. I might downrate it slightly to EI 20 with R09, or if going for a gamma nearer .55.
So in this application, it looks like the Rodinal is slightly more active than the R09 at the same 1:100 dilution, but not radically so. It will take further experimentation to find exact equivalents, but there's not enough difference in this application for me to want to dial in a 2% change in gamma. I'd rather be shooting real images. Next time with straight R09 and KB25, I'll probably extend development very slightly and see if the EI comes up a hair to equal the Rodinal speed. But I'll probably also get on with trying KB25 in both Rodinal and R09 laced with sodium ascorbate and borax before I do that.
I haven't done any enlargements, or looked under a microscope to detect grain differences yet.
Hope this helps folks who are looking to get a handle on how Rodinal compares to R09. I don't know about extrapolating from this information to other films, dilutions, or developing times. Test and let us know what you get.
And thanks again to Roman (rjr) for providing more concrete information on R09 than I've seen elsewhere.
Lee
I shot half a roll at EI 25 and processed it in Rodinal and then shot the second half of the same roll and processed in R09. I shot with a Bessa R3A and 75mm Color Skopar at middle apertures and in auto-exposure mode through an ExpoDisc (diffuser), and adjusted the film speed setting to get exposures for Zones I, V, and VIII. Both halves of the film were developed in 300ml water (I use local spring water that I've found to be good for developing) with 3ml of developer concentrate, and both at a time of 12 minutes. Agitation was constant for the first 45 seconds, then two torus inversions and a rap and quarter twist on the bench once each 3 minutes. They were developed at ambient temperature in the darkroom, about 74 degrees.
I measured negative density with a diffuse light above a Gossen Luna Pro F and enlarging attachment, with the negative center covering the enlarger attachment aperture. The Luna Pro F has 1/3 stop (0.1 log density) markings that are spaced enough for reasonable interpolation to about 1/12 stop. (I know this assumes linear response, but it's what I have to work with.)
I found that the Rodinal gave slightly higher density, a bit less than 1/6th stop, and slightly higher gamma, .605 for R09 and .619 for Rodinal. With the Rodinal and this processing routine, EI 25 looks like a good place to start with KB25. I might downrate it slightly to EI 20 with R09, or if going for a gamma nearer .55.
So in this application, it looks like the Rodinal is slightly more active than the R09 at the same 1:100 dilution, but not radically so. It will take further experimentation to find exact equivalents, but there's not enough difference in this application for me to want to dial in a 2% change in gamma. I'd rather be shooting real images. Next time with straight R09 and KB25, I'll probably extend development very slightly and see if the EI comes up a hair to equal the Rodinal speed. But I'll probably also get on with trying KB25 in both Rodinal and R09 laced with sodium ascorbate and borax before I do that.
I haven't done any enlargements, or looked under a microscope to detect grain differences yet.
Hope this helps folks who are looking to get a handle on how Rodinal compares to R09. I don't know about extrapolating from this information to other films, dilutions, or developing times. Test and let us know what you get.
And thanks again to Roman (rjr) for providing more concrete information on R09 than I've seen elsewhere.
Lee