Acros developing times with Pyrocat?

[Michael Mutmansky]

Has anyone out there made any tests with Acros in Pyrocat HD?

I am interested in developing to a DR of 1.0-1.1 and am planning to try rotary and minimal agitation methods. Hopefully, there is some experience out there with this film already. If not, I'll report back once I have made a full set of tests.

Thanks,

---Michael

[John D Gerndt]

I just did a roll of 120 Acros, rated at 50ASA, 1:1:100 at 75F, 10 min, normal agitation (10 out of 60 seconds). The stain is strong/dark and the negs have a high density, perhaps the level you are looking for. I do not have a densitometer (or even a good guessitometer). The only testing I found re: Acros is in an article by Sandy King on the Unblinking Eye web page.

I will contact and projection print these tonight. I'll show you mine if you show my yours

[Henry Ambrose]

I have pretty much the same report as John. I shot at a range of speeds, developed for 10 minutes at 70 degrees F. After the subsequent printing session I decided it needed to be shot at 50 and given 10-11 minutes. Thats 1:1:100 with mild agitation every minute. From what I've seen of Pyrocat semi-stand development (I've only done TriX and HP5 this way) you might gain back some speed and maybe get it to 80 or 100. I'd like to hear what you get from your tests.

[John D Gerndt]

My impression of this Acros in Pyropcat-HD is good. I got some long printing times (50-80 seconds at f8 – my normal is 20 seconds) on my standard Beseler 45MX enlarger but they did print and are Very sharp. I ran mine at 75F and I think I’ll back off to 70F for 10 minutes at 1:1:100 for the next round matching Henrys experience.

The tiny contact prints (120 size) are hard to evaluate for tonality but my subjective impression is that they are great! Too bad one must optimize for one printing method at the expense of the other.

[Michael Mutmansky]

John and Henry,

Thanks for the notes.

John, how is the contrast at the 10 minutes with 75 degrees? If you drop the developer temperature, you will be reducing the contrast of the negative, and the gradient. If you seem to have hit good contrast with the film, then you may need to simply reduce the exposure (rate it at a higher ASA). One thing I have heard is that some people feel Acros is a true ASA 100 film, so this might account for the long printing times you experienced.

Typically, a staining developer will have a higher base exposure due to non-proportional stain. Pyrocat HD does a great job of minimizing this, so I would expect a properly developed and exposed negative to require more exposure than a comparable negative, but not as much more as you have indicated (maybe 50% or so more exposure). The exception would be in cases where the film is very receptive to staining (like Bergger 200). Then, the difference may be much more.

If the staining is a problem, you can increase the part 'A' of the developer a bit (say, to 1.5:1:100). This will increase the silver to stain ratio, and will only slightly increase the contrast of the developer mix. Part 'B' controls the overall contrast of the developer more than part 'A', and part 'A' has the restrainer that keeps the developer from uncontrolled staining.

I'm still waiting for the film to come in, but I have some 120 Acros, so I may start some tests based on your comments above.

---Michael

[John D Gerndt]

Michael, you seem to know a lot more about the manipulations that I do. What is meant by gradient?

Can you point me to a reference that explains how time and temperature have separate effects?

To address your question (I am more and more finding that I need hard data to speak to the important questions – I need a calibrated densitometer) The contrast level seems OK which is to say prints look a bit flat at grade 2 and a bit harsh at 3 ½. The highlights are hard to get right. The complexity of the image forbids burning in.

The contact images (on AZO) look great!

I found the data that Sandy King provided about Acros:----- 5.5 minutes gets you a G of 5.5, 8 minutes gets you .6, 11 will get you .7 and 16 gets you almost to .8-----Acros in Pyrocat-HD, 2:2:100. BLUE channel

Here again though is a term unknown to me: “G”. Is this for gamma? How does one use it? Can it be converted to DR?

I did my shoot based on a guestimated SBR of 4 (today’s is only 3) going by his posted times for silver printing:

SBR 7.5---4:15......... SBR 7.0---6:00......... SBR 6.0---8:30......... SBR 5.5---10:45

1:1:100 @ 70F

Two things seem to nag at me: my SBR guess must have been way off (I had only an incident meter) and I should have used the full 100ASA. It seems that you are better off reducing the ASA in overly contrasty situations right?

[Michael Mutmansky]

John,

What I meant was that you can't reduce the temperature without affecting the contrast of the negative. Dropping the temperature is similar to reducing the development time.

G (or actually, G-bar as it is termed, with a line over the G) is the gradient of the film curve. The gradient is a method to express the slope of the film response curve as a straight line, and it is used to determine how much contrast the negative will produce for a given lighting condition. Also, the film ASA as it is rated by the manufacturer is normally based on a very specific gradient slope and also a specific DR.

DR is the dynamic range of the film expressed in logarithmic units. It is a way to express the contrast the negative contains, from highlight to shadow. G and DR are independant expressions and do not have a direct relationship, although they are related.

G and SBR (subject brightness range) can be related through geometry, but the target DR of the film must be defined to be able to determine the SBR that the film will capture at a given G. I don't think in terms of G because that is a more general term that describes a film, and is useful when the specific tagret DR is not known or defined. I generally think in trems of SBR for a film (at a specific DR).

If you want a good understanding of how all of this works, I recommend that you purchase a copy of Phil Davis' book Beyond the Zone System. It is not a requirement that you get a densitometer to use the information well, but it does help.

Based on your comment that the prints on Azo look good, you may be able to reduce the development time a bit and get satisfactory contrast for silver. Azo requires a more contrasty negative than silver.

Note also that the BTZS book has an approach to determine SBR USING AN AMBIENT METER. This approach is actually quite simple, and many people use it with great success. So, that approach will allow you to determine the SBR accurately even without a spot meter.

Can yo point me toward the citation you made of Sandy's indicating the SBR values and development times for 1:1:100? I didn't see that reference when I looked around for it.

---Michael

[John D Gerndt]

The only reference to Acors was in the seminal article Sandy King wrote for the Unblinking Eye: Introduction to Pyro Staining Developers. I downloaded the article into Word so I have lost the exact address. Most of that articles data was pointed at high (1.7) DR work for AZO and Paladium Pyrocat HD at: 2:2:100, but he mentions that to get to good silver densities you need only reduce the developer to 1:1:100. He does not provide charts/tests to support this.

I have seen most of his responces to questions on Michael and Paula website -------------http://www.michaelandpaula.com/mp/AzoForum/

Thank you for the reference to a good text. I will seek it out. One of these days I will have a grip on how to consistently make good negatives.

Cheers,

PS I read recently that Pyrocat HD may be soon sold in liquid form, that would be nice...

[Michael Mutmansky]

John

O.K. I saw the reference you used. I didn't know where you were getting the 1:1:100 values because I didn't realize you were extrapolating from Sandy's data. Generally, dropping from 2:2:100 to 1:1:100 will reduce the contrast a bit but I don't think it will drop it from 1.7 down to 1.0 or so. I think that a time adjustment may be required also.

Pyrocat is available from Bostick-Sullivan in liquid form, but personally I prefer to mix it myself. The real cost savings with this developer is realized by the hand mixing of the materials.

I would suggest that you make sure they are doing the phenidone version of the developer if you choose to buy it premixed. I found the metol verion to cause more staining and also more variability due to the metol oxidizing.

---Michael

[John D Gerndt]

Thanks Michael, you have been very helpful. I have just developed some sheet film, J&C 200and some HP5+ in Pryocat HD (Photographers Formulary) and am getting much better results. I think that maybe Acros just takes a stain in a big way.

I am also pretty sure that temperature affects the development in a non-linear way. I have read figures of 8-9%/ degree C between 18 & 22C. My shifts at 14C and at 24C where quite dramatic, seemingly more like 12%, but it is difficult to sort everything out. I did some semi-stand developing in a Nova (heat/temperature controlled – it is only 55F in my darkroom) vertical unit that may help me get things consistent. I envy you your skills knowledge and equipment. I wonder what control feels like?

Well, on now to the tasks at hand. Again, thank you for your assistance. I have benefited greatly from the kind help of several persons on this forum.