Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,296   Posts: 1,535,730   Online: 841
      
Page 1 of 2 12 LastLast
Results 1 to 10 of 13
  1. #1
    fhovie's Avatar
    Join Date
    Mar 2003
    Location
    Port Hueneme, California - USA
    Shooter
    Large Format
    Posts
    1,247
    Images
    92

    PMK - Pyrocat - Issues and View Camera Mag

    I used PMK for a couple of years and found it to be very satisfactory for 4x5 film. I found it to be too grainy for most roll film - even 6x6 for making nice 16x20 prints from MF or even past 8x10 on 35mm. So I started using Dixactol for roll film and was very pleased. Now for the last 6 months I have been using Pyrocat for almost all my films and I must agree with the article I just read in "View Camera" by Steve that shows a drop out of shadow values in PyrocatHD. I have read Sandy's info on Pyrocat and he lists a slight increase in film speed that I have not seen. So I am confused about 2 things:

    1) In Steves article he lists an Hydroquinone as an ingredient. The formula I have lists that ingredient as Phenidone. I have been using Phenidone. I have wondered if adding some Hydroquinone to PyrocatHD might increase the film speed a little.

    2) How is it that Sandy lists an increase in film speed - I have not seen it in my work. My work shows very much like the examples Steve shows in his article. Not that the change is a deal breaker.

    PMK is grainier across the board and that will of course cause the images to appear sharper. OK for LF and ULF but I like the finer grain for roll film and the performance of Pyrocat for alt processes is very good - no complaints at all on film speed when developing for AZO or Kalitype at 2:2:100. It is just at 1:1:100 with minimal development for enlarging that I see a drop off in the lower values. -

    So Steve - Sandy ... Is it Hydroquinone or not? Should I go for 2:2:100 for enlarging with less development time to keep densities and grain under control??

  2. #2

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Quote Originally Posted by fhovie

    1) In Steves article he lists an Hydroquinone as an ingredient. The formula I have lists that ingredient as Phenidone. I have been using Phenidone. I have wondered if adding some Hydroquinone to PyrocatHD might increase the film speed a little.

    2) How is it that Sandy lists an increase in film speed - I have not seen it in my work. My work shows very much like the examples Steve shows in his article. Not that the change is a deal breaker.

    The article in View Camera is incorrect in stating that Pyrocat-HD contains hydroquinone. It does not and never has so I have no idea why Steve Simmons would have said that it does.

    About film speed, bear in mind that accurate comparison of the EFS of film in different developers requires fairly sophisticated testing methodology. In fact, I will go so far as to say that it is virtually impossible to measure accurately the EFS produced by a given developer without the use of sensitometry. Field tests, given the inherent inaccuracies and inconsistencies in exposing equipment (lens, shutters, etc.), lack the level of accuracy needed to make this kind of comparision. Another issue is that for the test to be reliable the films in both developers need to be developed to exactly the same effective printing density range *for the process being compared.* If they are not developed to the same CI the film that has more contrast will indicate a higher EFS.

    Three things you should know about my procedures. When I carry out tests to compare EFS with a particular film/developer combination I use a light integrator to expose the film, thereby assuring accuracy in exposure to about 1/100 of a second. This eliminates the inconsistencies of field tests. Second, before I even attempt to compare EFS I determine what development time is needed to achieve the same CI, or effective printing density range with both developers. The third thing is that all of my comparisons of EFS are made based on either blue light analysis of the curves (for graded silver papers) or with UV analysis (for alternative processes).

    OK, when I do the tests as above I see a slight speed increase with Pyrocat-HD over PMK, definitely not a loss of film speed. There are of course several things that could explain the discrepancy in our results. However, my own intuition on this is that if anyone is observing lower EFS values with Pyrocat-HD than with PMK the most probable explanation in my opinion is that the Pyrocat-HD and PMK comparison negatives were not developed to the same CI.

    Another final issue is that all of my tests have been made with graded silver papers. VC papers respond differently to the different color stain of PMK and Pyrocat-HD and this makes it even more complicated to determine the effective CI of the comparision negatives, because with VC papers you also have to consider both the color filter being used, and the specific color sensitivity of the paper. The issue is really quite complicated and outside of the realm of my own interests since I am primarily interested in alternative printing.

    Sandy King
    Last edited by sanking; 07-25-2004 at 11:22 PM. Click to view previous post history.

  3. #3
    gainer's Avatar
    Join Date
    Sep 2002
    Posts
    3,726
    Images
    2
    That mention of hydroquinone may be my fault. I commented in several places that hydroquinone is a staining developer when used with very low or no sulfite, and that is true, but it is not Pyrocat-HD even when you substitute amount for amount of catechol.

    Hydroquinone and catechol (aka pyrocatechin) are first cousins, having the same empirical formula but different placement of one of the OH groups. The color of the stain image is different.

    If View Camera actually called the hydroquinone formula Pyrocat-HD or any other kind of Pyrocat, it was irresponsible research on their part. Pyrogallol, catechol and hydroquinone all belong to the hydroxy benzene category of tanning-staining developers, but all are different in several ways.

    Where did the idea come from that large grain is inevitably synonymous with apparent sharpness? T'aint necessarilly so. Large grain can also result from infectious development, which can destroy resolving power. Highly alkaline developers containing the hydroxy benzines and little or no sulfite can show infectious development. I have not seen evidence of it in ascorbate developers that I have used.
    Gadget Gainer

  4. #4
    fhovie's Avatar
    Join Date
    Mar 2003
    Location
    Port Hueneme, California - USA
    Shooter
    Large Format
    Posts
    1,247
    Images
    92
    I would like to mention a quick note here: I do like Pyrocat very much and appreciate Sandy's work in developing it and documenting it. [and supporting the folks that take advantage of all his work - like me] You have my thanks Sandy. I also use graded silver fiber papers mostly but others frequently as well. For enlarging, I typically try to keep densities down like many folks who develop for the enlarger. Less dense negs seem sharper and smoother when enlarged.

    As far as grain and sharpness; that is the opinion of many - including several authors I have read. Edge effects, which increase the appearance of sharpness are less noticable in very fine grain structure films [like tech pan, pan f, etc] High solivent developers certainly erode edge effects and can create images that do not appear as sharp and are certainly less grainy. It is this that makes TRI-X and Microdol a nice combo - the coarse grain of TRI-X gets smoothed out by the high solivent developer and creates a sharp appearing yet less grainy print.

    I will continue to use Pyrocat and will experiment with 2:2:100 [abandoning the 1:1:100 for a while] and develop times for enlarging and see what effect that has on the low values as far as film speed. I do not have a densitometer [yet] and so my results are not lab stuff - just - what do the prints have or lack when they hang on the wall. That doesn't mean I am sloppy or non technical - just more pragmatic about my methodology - not unlike many other folks that hang around here.

    Anyway let no one think I am throwing stones and anyone - Sandy or Steve - I just want to understand these tools better. So thanks

  5. #5
    skahde's Avatar
    Join Date
    Feb 2004
    Location
    Germany
    Shooter
    Multi Format
    Posts
    425
    Images
    4
    Patric,

    you raise an interesting question here with respect to infectious development and pyrocat-hd. Three sources, myself included, on a german b+w forum found that pyrocat good as it is for small formats did not have quite the rendition of fine detail that we saw with something like barry thorntons metol 2-bath or D76h 1+1. Maybe infectious development is the key to this and we should look for a way to control it a bit without affecting the positive aspects of pyrocat to much e.g. good proportional stain.

    Presumably there is room for improvement in this direction but I understand that pyrocat was never intended for roll-film formats by Sandy and he will not put much effort into this.

    best

    Stefan

  6. #6

    Join Date
    Nov 2002
    Location
    Melbourne, Australia
    Shooter
    Medium Format
    Posts
    982
    I do my sensitometry of negatives with a spot meter (minolta, reading to 0.1 stop), using bright cloud daylight as a light source. At this level of accuracy, and with negatives that are deliberately developed to a contrast of only about 0.5, I get a bit more speed out of the Metol version of Pyrocat-HD than I do from PMK (HP5 roll film). Also, I use approximately half strength Pyrocat-HD (3+3+500) with minimal agitation as described by Sandy on the Azo forum at

    http://www.michaelandpaula.com/mp/AzoForum/default.asp

    Go to Film development and look for the post

    Minimal Agitation and Adjacency Effects Sandy King 4/15/2004

    I have a feeling that dilute developer plus minimal agitation might be the way to go for speed, rather than strong developer. The reason that I use metol instead of phenidone is that I think I either got a bad batch of phenidone or I made some sort of mistake in mixing (I had a stock solution of phenidone in alcohol, maybe not a good thing). Anyway, I like metol, and the metol version of Pyrocat-HD is very pleasing.

    FWIW, I get 320 with HP5+ and 250 with Neopan 400 (both at 0.1 above fb+f for zone I as measured by the same Minolta spot meter, accurate shutter in a Mamiya 6). My maximum print size is 12"x16"

  7. #7

    Join Date
    Nov 2002
    Location
    Melbourne, Australia
    Shooter
    Medium Format
    Posts
    982
    I meant to add to the above post is that I find the sharpness and grain very good indeed, and with VC paper I get good control of mega highlights such as church windows in interior shots etc. However, I can't claim to have compared other developers recently.

  8. #8

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Quote Originally Posted by skahde
    Patric,

    Three sources, myself included, on a german b+w forum found that pyrocat good as it is for small formats did not have quite the rendition of fine detail that we saw with something like barry thorntons metol 2-bath or D76h 1+1. Maybe infectious development is the key to this and we should look for a way to control it a bit without affecting the positive aspects of pyrocat to much e.g. good proportional stain.

    Stefan
    I have compared Pyrocat-HD to D76 1:1 (and to PMK) but not with Thornton's 2-bath metol formula. The comparison with D76 involved both tests for resolution in lppm, using a standard Air Force resolution chart, and a visual comparison of prints 20X24" in size from 4X5" comparison negatives. My conclusion was that PMK and Pyrocat-HD negatives were virtually identical in sharpness and resolution, and both were significantly better than D76 1:1 in both categories.

    With regard to sharpness let me add that with many developers it is highly dependent on type of agitation. With Pyrocat-HD in particular negatives developed with rotary agitation tend to be not quite as sharp as those developed with minimal agitation.

    Assuming, however, that we could improve on the Pyrocat-HD formula in terms of the rendition of fine detail for 35mm or roll film work I would suggest two possible approaches. 1) Reduce the amount of phenidone by about 50%, or 2) replace the phenidone with metol at the rate of about ten parts metol to one part phenidone. Phenidone has great regenerative qualities and if there is too much of it in the formula the result will be a loss of sharpness from reduced adjacency effects. So either reducing the amount or substituting metol could provide slightly sharper results. I would speculate, however, that the method of agitation would continue to play an important role in apparent sharpness irrespective of these changes.

    Sandy King

  9. #9

    Join Date
    Oct 2002
    Location
    Denver, CO
    Shooter
    Multi Format
    Posts
    22
    Sandy,

    I am very impressed with my results with Pyrocat HD but I was wondering why a milky powder forms on the bottom of my part A bottle. I mix it with distilled water. I also use alcohol to dissolve the phenidone. Thanks for your efforts.

    Greg

  10. #10

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Quote Originally Posted by Greg Rust
    Sandy,

    I am very impressed with my results with Pyrocat HD but I was wondering why a milky powder forms on the bottom of my part A bottle. I mix it with distilled water. I also use alcohol to dissolve the phenidone. Thanks for your efforts.

    Greg

    Greg,

    Sounds like some of the chemicals are not going into solution. This is odd because I have not previously heard of this problem and have never experienced it myself. I would recommend as a general precaution that when adding the chemicals you make sure that each goes completely into solution before adding the next. However, the only really stubborn one is phenidone and since you are already mixing it with alcohol before adding it to the solution I am really stumped as to why some of the chemicals appear to be settling out of solution.

    Sandy

Page 1 of 2 12 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin