Using Rodinal as a compensation dev for HP5

I shot some HP5 which I rated at 200 ISO. The exp. range was about 7 stops. I placed the shadows on zone three. I want to use Rodinal as a compensating dev. t o compress the range to about 5 stops. Questions: 1 Is 1:100 a good dilution ratio for this? 2 What is an approximate time for development? 3 Also, I exposed some Agfa 100 at 64 ASA - same kind of exposure range. What would be an approx. time for that? 4 I have a daylight tank which holds 6 films and takes appox 1100 ccs. I read somewhere that there may not be enough dev in a dilution of that strength for th e film area. Is this true? If so how do I make a high dilution but make sure th ere is enough dev? Only do three at a time? Many thanks to everyone in advance. I would also like to thank everyone who con tibutes to this BB. It has helped me tremendously. Yaakov Asher Sinclair

Hi Yaakov, I've used Rodianl 100:1 for night shots with good results. I did find it tricky. A couple of times I got streaking when I would just lay a neg in it and walk away for about 25min or longer. I did use twice the amount of developer I normally use for this. I've never had any luck pushing up the contrast on HP5, but then again I haven't used that much of it. You could try one sheet, R 100:1, look at with a green safety light at about 20 or 25 min. and see what's there. I'd probably aggitate once a min. for 5-10 sec. Best, David

Yaakov,

Agfa recommend that 500ml of concentrate will process approximately 50 135-36 (120, 8x10) films from which we find that you need 10ml for each 80sq in of film (8x10) or 2.5ml for each (4x5).

In 1100ml of working solution you will have 11ml of concentrate - just enough for 80 sq ins.

Find a work-around, though, because the results can be stunning.

On the question of times at 20?C Agfa give the choice of 2 CI ratings for 1+100 in a tank:

HP5 Plus: 0.50 = 20 mins (ISO 160) & 0.45 = 15 mins (ISO100)

Agfa APX 100: 0.60 = 20 mins (ISO 100) & 0.55 = 15 mins (ISO 64)

I have not processed either of these films for quite a while and so I don't have any way of checking the advised starting points. I do, however frequently process TMX/TMY to a CI of about 0.47 and my time is about 10 mins at 24?C. I am making negs for a condensor enlarger.

Cheers ... WG

As Walter points out; when a developer is used in compensating mode, it's the amount of raw developer per unit area of film that's important, not the dilution. What you're trying to do in any compensating technique, is starve the highlights of the negative of developer, so that they can't reach a high density. This means using the bare minimum amount of developer concentrate, and also minising agitation of the film during development. Using a two bath developer is another way of limiting the amount of developing agent available to the film and acheiving a compensating effect.I suggest that substantially less than 2.5 ml of Rodinal concentrate should be used per 5x4 sheet to give any useful compensation, regardless of how much water it's diluted in. The dilution, in this case, will only regulate the total developing time. Agitation should be normal for the first 20% of the developing time, and then reduced to a bare minumum (perhaps 1 turn of the film every 5 minutes) for the remainder of the time.