My apologies, I misinterpreted what you said!
Sorry Paul, I was talking about effects of minimal or regular agitation in water bath or earlier in B bath. On my negatives developed in Rodinal I can clearly see benefits of after water bath. It's my habit to process short strips of film (3-5 frames) to see what is going on. As somebody who has been bitten by "snakes" of under agitation I will stay away from any sort of "minimal" agitation with any developer.
1) I have found that for my needs, many (most?) films perform better at a minimum of five minutes in Bath A, and in some cases I extent the time in A to 6.5 minutes. I don't exceed 5 minutes in Bath B. I have experimented with increasing the time in Bath A as much as 8 minutes and it had no negative effects on a film like Tmax 100. (Click to see example)
High contrast, slow speed films like Ferrania Orto perform beautifully at the standard 4.5 minutes in each bath. It tames some of the contrast without making negs look "soft". See example here.
2) I have also found that BTTB reduces effective film speed by about 1 and a half stops for many films. For certain circumstances, that is excessive, but with how I work, it's not unreasonable in many cases where I use a tripod and long exposures. The Ferrania Orto produced great negs at 25 ASA, so just one stop under box speed.
3) I find certain films really sing in BTTB and others produce mediocre images. Fomapan 400 and 100 produce beautiful negatives in BTTB.
Alex,
That's what surprised me also when I started playing with BTTB. I use an older Ilford Ilfospeed 400 VC head and don't think I have ever had a negative that printed near perfect the first try when the head was set at G2, but that's what happened using this developer. It's God awful easy and almost seems like cheating.
Alex,Same feeling. If you get the exposure right, printing really becomes a matter of finding the right grade. That's what makes split-grade printing so interesting with BTTB. Because you don't have to fight with you negative, it opens it to various interpretations.
But it won't save your neg if you don't get the exposure right. I have a few to prove that...
With the weather here having been either wet, real cloudy and gray, or too cold, I have spent the past few days completing my curve family using BT2B developer........and it wouldn't have mattered if the weather was great, I would've completed it anyway, I think it's valuable time and film spent. I will say that when I started this endeavor of mixing my own developer and starting with BT2B, I did not anticipate using it to develop TMX relative to "N+" development. I figured I'd be using XTOL for those and relying on BT2B for when needing that compensating effect. But in my searching and reading I found that it was certainly a warranted and doable thing. I had some confusion at first on the term "divided" versus "two bath" (AA called it "two solution"). A true "divided" developer, if I understand it correctly, would not have much or very little development occurring in bath A. But I've just opened myself up and may still be displaying some confusion on the process, idk.
So here is my BT2B curve family. I don't know if I needed to actually develop bath B for as long as bath A when I got to the longer development in the 7.5 min and 9 min range, so I did so just to be consistent. I "think" someone mentioned early on that extended time in bath B was not harmful to the outcome. Adjusting the 4.5 min curve to the left with its whopping 1 2/3 stop loss of speed does not allow the curve to reach the N-2 mark but it is on that trajectory. What I like about that curve is that when I compare it to my N-2 curve with TMX and XTOL 1+0, the BT2B curve exceeds the densities obtained on the XTOL curve from Zone I 1/2 to Zone IV 1/2, not by much but it does exceed it, indicating beneficial development in those low value areas. As to the 9 min curve, it clearly allows me to interpolate the development time downward to try and hit that target better but I'd do that pictorially, not with another test sheet.
As can be seen by the EI's for each curve, all had to be shifted back to the left on the log exposure scale by 1 2/3 to 1 1/3 stop to reflect a Zone I density of 0.1...........just the basic fixed speed point method of determining speed with the ZS. As you can see the target for "N" development times is a Zone VIII density of 1.2 +- 0.05 (indicated by the red dashes above and below each target) to try and develop the negative to a relatively consistent NDR of 1.1 from Zone I to VIII. I found it interesting that the 5.5 min curve reflects EI40 and the 6 min curve reflects EI32, I would've thought it would show the reverse.
And I say with all due respect, there is no need for opinions on flaws associated with how speed is determined using the ZS, it's not my intent to spark a discussion in this thread on what some think is a better way, thank you. I'm just reporting that's how I've done it here and how I've always done it. I can't find any reasons to argue with my results so far.
I look forward to giving these curves their pictorial chances going forward. I'm certainly open to constructive criticism on how better to utilize BT2B as it pertains to these curves or perhaps possible better development time and agitation scenarios with A and B, which I'd be glad to implement at some point in the future. I'm also, intrigued with that idea of having two other bath B mixtures available, one with 7g of sodium metaborate and one with 20g of sodium metaborate for use in dealing with different SBR's using BT2B.
View attachment 388441
From Edge of Darkness the main idea of it seemed to be that it can provide printable negatives from scenes of widely varying contrast on the same roll and reduced development of highlights due to minimal agitation in part B.
This cannot be graphed but thanks for the data which is useful if contrast of all scenes is similar.
Well, yes. But.... Regardless of how much agitation is applied in Bath B, the developing agent(s) that soaked into the emulsion will be exhausted quickly in the high density areas. The reduced agitation facilitates edge effects more than anything.
I found the instructions for the discontinued Emofin, another developer where there is some development in the first bath.
They only mention agitation in both baths at 3sec (rotary processing?) and 1 minute intervals, in agreement with what you say, nothing about minimal agitation.
They give temperature correction factors by which to multiply the time at 20C, 68F.
18C(64F) 1.2, 20C(68F) 1.0....22C(72F) 0.85..... 24C(75F) 0.75....26C(79F) 0.6.
IDK if these factors work with BTTB.
The principle reason to use BT2B, IMHO, is control of extreme highlights (which also means you can have low and high contrast images on the same roll). You still need to expose the shadows adequately, of course.
@Chuck_P: Give the 20 grams a try. I attached two samples using 20 grams of metaborate. First image is from Kentmere 400 at EI 320 and the second image from Tri-X at EI 250. Five minutes in both baths.
I haven't yet tried the 7 grams amount. Might benefit more contrasty scenes.
I bet you could have used a EI of 64 on that shot. I bet that this one would wet print pretty easy also, but I could be wrong.
One thing to keep in mind is the test scene is relatively high-flare, which is both helping emulsion speed (at least from a fixed density criterion perspective) and reducing contrast.
Chuck, Looks good! With 4X5, different strength second baths should work great and actually make life pretty simple as far as Zone System work goes. I think Adam's had a film developer something like this. I know he had a 130 style paper developer that operated on the same principle and I have used that before.
Yes, but Ansco/Agfa 130 is still used today even for VC papers. I like it for its shelf life and the way it holds up in an open tray. I was thinking it was Adam's who teaked the 130 developer to a two-part with different strength carbonate solutions in a second bath for slight contrast control. Of course this 75 year old mind isn't as sharp as it used to be and I could be wrong on that one. I'm going to use BTTB to develop a couple of sheets of Shanghai GP3 to see if it stored well and to test an old uncoated Angolan 90mm 6.8 against my newly arrived coated one. We'll see how it goes.Thanks, I'm quite please so far, the actual printing of the negative may be the best test probably, but I have no paper at the moment. I think that may be the Ansco 130 paper developer, not sure..........but undoubtedly that was used with papers no longer available.
Yes, but Ansco/Agfa 130 is still used today even for VC papers.
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