I've been meaning to give Acros a try to replace APX100 in 120, but judging by the results of the testing I've done this week, it seems as if it does not like me: shadow details seems impossible to get unless I shoot at an EI of 25, EVEN THOUGH a densitometric reading indicates an EI of 100 as optimal. Here are the details of the testing which brings me to this confusing conclusion:
Efke R25/Rodinal 1+50 (8mins)
FP4+/XTOL 1+1 (8mins)
Acros/XTOL 1+1 (8 mins)
Acros/Rodinal 1+50 (10 mins)
I exposed a grey card for Zone I, focussing on infinity, and filling up the frame of my camera, a Yashica-D TLR. It was biting cold that day, but all the films were subject to the same temperature. I waited two days before developing them, so they were at room temperature.
I took exposures of the card at ISO -3, -2, -1, 0, +1, +2, +3 relative to box speed, and used the remainder frame to take a shot of the same subject at ISO -3, 0, +3. That means that for, say, Acros, I have shots at EIs 50, 100 and 200 of the same subject.
The grey card is held in the exact same light as the subject, so I use the meter reading I have from the card to expose the subject.
I went to my favorite lab to have the Zone I measured by an X-Rite visible light transmission densitometer. The lab is a respectable pro one where I have seen customers entrusting them a full banker's box of 4x5. The person who did the measurements is an ex-Kodak employee.
The results for Efke and FP4+ were rather predictable: given a target density of 0.10 above fb+f, I should use an EI of 50 for Efke R25, and one of 250 for FP4+. Rodinal 1+50 gives a speed increase, and so does XTOL 1+1 according to each developer's documentation.
I looked at the pictures of the subject I took at these EIs and it gives me excellent shadow details for each film. Once I test for the highlights, I should have an optimum dev time for each combo. Densitometry agrees with Eyeballs.
The real problem is with Acros. With XTOL the densitometric reading gives me an EI of 100 for a density of 0,13 above fb+f. Had I tested more precisely, an EI of 125 would have probably been right on the money. However, when I look at the picture I took of the subject at EI 100, I have ZERO, nada, zilch, rien, in the shadows. The film is severly underexposed, and it's only at EI 25 that it looks normal. With Rodinal the problem is similar.
I am absolutely befuddled: why is it that Acros would react properly with a grey card and not with a real subject under the same light? If the densitometry had agreed with the actual subject shot, then it would make sense, but here it does not.
I checked my record, and in the exact same conditions I exposed FP4+ and Acros at f/8, 1/125s, so there couldn't be more than a stop of difference between shadow details in either film if the densitometer is to be trusted. They were even developed together in the same tank, so they were subjected to identical agitation patterns. There's no streaking, so development looks uniform. Thus, THEORETICALLY they should give proximate EIs, and similar shadow details. Practically, they don't.
My XTOL is good, based upon the FP4, my Rodinal is good based upon my Efke, everything else is normal except Fuji's film. Why, oh why??
I guess I need to re-test Acros and see if I can reproduce this problem, but right now I have no clue as to which variable I should control: Dev time or exposure?
Efke R25/Rodinal 1+50 (8mins)
FP4+/XTOL 1+1 (8mins)
Acros/XTOL 1+1 (8 mins)
Acros/Rodinal 1+50 (10 mins)
I exposed a grey card for Zone I, focussing on infinity, and filling up the frame of my camera, a Yashica-D TLR. It was biting cold that day, but all the films were subject to the same temperature. I waited two days before developing them, so they were at room temperature.
I took exposures of the card at ISO -3, -2, -1, 0, +1, +2, +3 relative to box speed, and used the remainder frame to take a shot of the same subject at ISO -3, 0, +3. That means that for, say, Acros, I have shots at EIs 50, 100 and 200 of the same subject.
The grey card is held in the exact same light as the subject, so I use the meter reading I have from the card to expose the subject.
I went to my favorite lab to have the Zone I measured by an X-Rite visible light transmission densitometer. The lab is a respectable pro one where I have seen customers entrusting them a full banker's box of 4x5. The person who did the measurements is an ex-Kodak employee.
The results for Efke and FP4+ were rather predictable: given a target density of 0.10 above fb+f, I should use an EI of 50 for Efke R25, and one of 250 for FP4+. Rodinal 1+50 gives a speed increase, and so does XTOL 1+1 according to each developer's documentation.
I looked at the pictures of the subject I took at these EIs and it gives me excellent shadow details for each film. Once I test for the highlights, I should have an optimum dev time for each combo. Densitometry agrees with Eyeballs.
The real problem is with Acros. With XTOL the densitometric reading gives me an EI of 100 for a density of 0,13 above fb+f. Had I tested more precisely, an EI of 125 would have probably been right on the money. However, when I look at the picture I took of the subject at EI 100, I have ZERO, nada, zilch, rien, in the shadows. The film is severly underexposed, and it's only at EI 25 that it looks normal. With Rodinal the problem is similar.
I am absolutely befuddled: why is it that Acros would react properly with a grey card and not with a real subject under the same light? If the densitometry had agreed with the actual subject shot, then it would make sense, but here it does not.
I checked my record, and in the exact same conditions I exposed FP4+ and Acros at f/8, 1/125s, so there couldn't be more than a stop of difference between shadow details in either film if the densitometer is to be trusted. They were even developed together in the same tank, so they were subjected to identical agitation patterns. There's no streaking, so development looks uniform. Thus, THEORETICALLY they should give proximate EIs, and similar shadow details. Practically, they don't.
My XTOL is good, based upon the FP4, my Rodinal is good based upon my Efke, everything else is normal except Fuji's film. Why, oh why??
I guess I need to re-test Acros and see if I can reproduce this problem, but right now I have no clue as to which variable I should control: Dev time or exposure?