Reading charts on PyroCat-HD

[Eric Rose]

Ok I'm challenged. I admit it. But I have no idea what the heck Sandy is trying to convey on these charts. http://unblinkingeye.com/Articles/PCat/PCat4/pcat4.html

What the heck is the "G" axis?

 

[Donald Miller]

Eric, rather then taking a chance on misinforming you, the link below may give you the information that you want. Good luck.

http://www.btzs.org/Articles/HowToReadFilmTest.htm

 

[sanking]

Donald,

Thanks for posting the link. Knowing of its existence will save me a lot of time in answering questions about some of the BTZS type charts I ocassionally use or reference in my writings.

Sandy

Eric, rather then taking a chance on misinforming you, the link below may give you the information that you want. Good luck.

http://www.btzs.org/Articles/HowToReadFilmTest.htm

 

[Eric Rose]

Thanks guys it was great reading. but I still can't figure out how I can use this information to determine what deveopment time I need for FP4 rated at say 100asa. Or 125, close enough.

If a person could get a copy of the full set of charts for 1:1:100 that would be fantastic.

 

[Donald Miller]

Thanks guys it was great reading. but I still can't figure out how I can use this information to determine what deveopment time I need for FP4 rated at say 100asa. Or 125, close enough.

If a person could get a copy of the full set of charts for 1:1:100 that would be fantastic.

Eric,

If you want to develop FP4 for silver then the CI would fall into .47-.52. (first table in the Unblinkingeye article). Then if you go down to the chart for FP4 developed in Pyrocat 1-1-100 read with the blue channel of the densitiometer (figure 16) you will see that the time looks to be six minutes at 70 degrees.(CI---.5) I believe that these tests are done with BTZS type tubes or on a motor base...Sandy normally does his tests using those means of agitation. If you use tray development, I would add about 20% to the indicated times.

The UV channel reading would be for those processes or paper that are exposed through UVA light sources. Not typically silver. Hope this helps.

 

[Eric Rose]

Awesome! Thanks Donald. Hey are you coming to the conference? One more question. Isn't there always LOL. I have been developing 6 - 4x5 sheets in 1300ml of solution and getting consistantly thin negs with PC-HD. What I have been doing is using 13ml of both solutions A and B then adding water to bring it up to 1300. I hope this is 1:1:100. Is this to much surface area for the amount of working A&B I am using? Or maybe I'm just mixing it wrong.

I have been using 20C for temp, 8 to 9 minutes for development time (creeping it up), 15sec initial agg. then 10 sec every minute until done. Water stop, and Ilford fix.

 

[sanking]

Eric,

If you want to develop FP4 for silver then the CI would fall into .47-.52. (first table in the Unblinkingeye article). Then if you go down to the chart for FP4 developed in Pyrocat 1-1-100 read with the blue channel of the densitiometer (figure 16) you will see that the time looks to be six minutes at 70 degrees.(CI---.5) I believe that these tests are done with BTZS type tubes or on a motor base...Sandy normally does his tests using those means of agitation. If you use tray development, I would add about 20% to the indicated times.

The UV channel reading would be for those processes or paper that are exposed through UVA light sources. Not typically silver. Hope this helps.

Donald is right about the type of agitation I use for testing film. Another thing to consider is that my development times are calibrated to graded silver gelatin papers. For VC papers you should add about 30% to the time indicated by the chart. If you make the adjustment you will have a time that should be useful for initial testing of most film/developer combinations.

Sandy

 

[Eric Rose]

I forgot to mention I use a tank and hangers. From my limited understanding of using tubes the times are quite different. Is there a general rule of thumb for the conversion?

 

[Donald Miller]

I forgot to mention I use a tank and hangers. From my limited understanding of using tubes the times are quite different. Is there a general rule of thumb for the conversion?

Eric,

Since I have not used tanks and hangers before, I don't know how much the agitation differs from tube and motorbase agitation...I would assume that it was less but I may be wrong...if I were in your shoes I would probably start my testing at about 9 to 9 1/2 minutes for pyrocat 1-1-100 at 70 degrees on FP4 if you are printing on VC paper. That should get you into the ball park.

 

[nworth]

To answer Eric's original question, different printing processes require different sorts of negatives for best results. Mostly, this can be reduced to different contrasts. The table in Sandy's article lists several different printing processes (conventional silver-gelatine and several alternative processes) and his conclusions for the best negative contrast index (CI) to use for each of them. The charts plot development time against gradient (G) for several films. While not exactly the same, CI and G measure contrast in similar ways. Here they can probably be used interchangeably.

 

[claudiosz]

I have some experience with your technical development system. My time is 12´45" for your temperature but with 5" agitation once a minute, printing on Ilford MG fiber paper. For 5" agitation at 3 minute intervals (minimal agitation for me) my time is from18 to 22 min. Sometimes, I agitate 5" with 5 minute intervals, time 28 / 35 min. (for maxximun enhanced sharpness).
An idea: expose six film sheets at EI 64, develop with one scheme of temp/agitation, and cut the times at 9 / 11 / 13 / 15/ 17 /20 min for each sheet. Look in a contact print for maxximmum black time and compare results. At nine minutes, I submerge the first sheet in stop bath (water with five drops of pure acetic acid) and fix, developing the 5 sheets for 11 min.; at 11, I pass another hanger to the stop bath and fix, developing the last 4 for 13 min. and so on. Finished the total developing time, I wash thorougly, and when the negatives are dry, I make the contact prints. The maxximum black time is the minimal time for obtainig the first black in the contact print.
Claudio Sz

 

[claudiosz]

Another tip: look the mood of the final print at your enlarging size; if I enlarge too much, FP4 have an "pointillize" look with minimal or extreme minimal agitation but midtones have an incredible enhanced sharpness. I like it for some subjects and dislike it for anothers.Is another powerfull aesthetics resource, and if you take four sheets of the same subjet, developing with different agitation schemes (at different developing times each) you can compare results at your enlarging size.

 

[noseoil]

Mix and development

Eric, did I read that you are mixing the "a" and "b" parts together first, then adding water? Mix the "a" with water first, then add the "b" for your working solution. This will help if your are mixing the "a" and "b" first. If thin negatives are still the result, slow down the speed a bit to build density.

Check the film's unexposed edge on a contact print with the correct contrast you visualized (high values where you placed them and shadows full). Is it a true black, or are you seeing a line where the film's base plus fog is still printing lighter? If so, add on exposure.

Here's an example from last weekend in which I neglected bellows extension until I was driving home. After some thought, I added development to get high values where they were needed, but exposure was still lacking, so the edge is still a bit thin. Efke 25 at asa 6, but no bellows factor was added (5/8 stop for this 180mm lens with 5 cm extension would have been correct), minimal agitation, 1:1:150 at 20 minutes, 70f so this was too thin for a decent print on grade 2 azo. tim

 

[Baxter Bradford]

Interesting thread since I had printed Sandy's UBEye articles yesterday as homework prior to getting set up for a switch to Pyrocat HD from PMK following my purchase of a Jobo processor. The very helpful posts and links here have filled in some of the gaps in my knowledge about specifics with the BTZS set-up.

It seems such a versatile and accomplished developer, all I need to do is get the ingredients....... and get the Jobo fixed with the right water supply.

 

[Kirk Keyes]

If you want to develop FP4 for silver then the CI would fall into .47-.52.

This CI would be for use with a condenser enlarger system on silver paper. If you are using a diffusion type enlarger, I would suggest a CI of around 0.58 or so.

 

[Eric Rose]

Interesting information. Sometimes the technically minded forget that there are a lot of photographers out there that don't want to get down and dirty with the charts etc. If someone has a new mousetrap that works, just tell us how to set it, not all the physics behind why it's better. The results speak for themselves.

In fact I add about 500ml of h20 to my tank then throw in the A and B solutions. Then bring it up to 1300ml. I hope this is the correct method.

The tips on this thread have been very helpful. Thanks one and all. I do appreciate the techno types, but I just don't have it in me anymore to be one.