Rodinal dilutions or speed change

Hi all, would really appreciate your help with this particular quandary. I moved away from film many moons ago concentrating exclusively on digital since as a professional nature photographer digital really has the edge in terms of speed and optics. However, I have returned to film to capture landscapes of my immediate region of Kent in England and I am enjoying the process, immensely. I'm using a Hasselblad 500c/m.

I've decided to concentrate my efforts on fine-tuning Rodinal with FP4 rather than playing with different brands and my question is this. Is it best to dilute to control contrast or alter box speed and alter development? 1:25 for dull light, 1:75/1:100 harsh light OR stick with 1:50 (or 1:75) and rate at 50 for harsh and under-develop and 80 for flat and over-develop? Does either method yield identical results? I wonder if anyone has ever done a test on this? Thanks in advance.

In general, developing more gives more contrast, developing less gives less contrast. Now, when you throw dilution into the mix as a variable, "developing more" becomes a little slippery.

My experience (with Parodinal, which is a homebrew developer that uses the same times and dilutions as commercial Rodinal) is that agitation also has a significant effect on contrast, which allows playing off time and agitation against dilution. My preferred process with Parodinal, after I'd been making and using it for a year or so, was 1:50 dilution, 40% more time than common recommendations for the film in use in that dilution of Rodinal, but agitation only every third minute. This gives a slight speed increase (rather than the slight loss common for Rodinal), because it allows developing more while producing normal contrast. There's also a slight increase in perceived sharpness, because local exhaustion tends to increase contrast across sharp edges. Finally, agitation every third minute is enough to avoid bromide drag that can result from loner rests (semi-stand or stand development).

So, bottom line, what I recommend for Rodinal and its derivatives is maximum "standard" dilution (usually 1:50), extended development, reduced agitation, no change in EI, but alter development time by the usual percentages (20% per stop? Best to test this for yourself) to control contrast.



.EDU Ultra 100, Parodinal 1:50 (11 minutes, agitation every 3rd minute), Wirgin Auta 4.5.

Thank you, Donald, that's really interesting. Certainly, retaining the box speed would be a great help, particularly for close-ups of flowers, for example, where every stop of shutter speed counts.
Would this formula be for normal contrast subjects with no excessive highlights? And, just so I understand correctly, for HC situations (backlight) I would half the speed and decrease development by 20% and vice versa for very LC subjects - fog etc?

I've used the extended development, reduced agitation for literally every lighting condition I shot in, in both 35mm and 120.

And you probably would want to reduce your EI if you're pulling the contrast, though that's not something I've done with roll films (and only about one time with sheets). I haven't noticed problems with highlights with my method; the compensating effect that reduced agitation and high dilution produce tends to compress the highlights a bit, rather than letting them block up. I'd suggest testing to be sure what you get, since your standards (or methods -- scanning or printing) may differ from mine. This is as much art as science -- and two painters using the same paints may have very different preferences and results, equally "good".

Thank you, again, I shall try your method in a variety of conditions on one roll and look forward to seeing the results. Love your analogy!

Robert Canis said:

Thank you, again, I shall try your method in a variety of conditions on one roll and look forward to seeing the results. Love your analogy!

Click to expand...

I agitate lightly and have also extended my dev times vs standard, and prefer 1+50, like Donald, though my Rodinal times are not as long as his since I agitate every minute. Keep in mind that with Rodinal in particular, more agitation also usually means more grain. Hope it helps.

Many thanks for your input. I've just done a test roll (120) in a variety of lighting conditions (flat to high contrast) using Donald's methods. Came out well. I concluded that for my purposes, 1:50 works for low/normal contrast scenes and 1:100 for HC. Looks as though I'll be continuing with 2 x backs.

Side note: if you add 5mg/L of potassium iodide to working developer you get a significant resolution/sharpness increase on FP4+ from my testing without altering characteristics or development time

That's interesting, though as Rodinal's a high acutance developer don't you already find it sharp enough?