Azo time

Discussion in 'B&W: Film, Paper, Chemistry' started by Silverpixels5, Sep 18, 2003.

  1. Silverpixels5

    Silverpixels5 Member

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    ok I'm gonna be trying this old azo out that I have, but don't know how long I should expose it. I hear it is suposed to be somewhat slower than regular enlarging papers. I'm going to have to make a test strip of course, but I don't want to make one that gives too little exposure for every step. I have to make the steps by hand since i have no step wedge. I have a limited number of sheets, and just don't want to make a test strip that turns out to be useless. So if it usually takes a 20 second exposure to yeild a proper print on regular enlarging paper, about what time should I start with for the azo? Thanks for any suggestions you can give. BTW my light source is from my enlarger which is about a meter above the baseboard.
     
  2. Aggie

    Aggie Member

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  3. Silverpixels5

    Silverpixels5 Member

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    I'll try that then for as many steps i can reasonably get on my little 5x4 sheet.
     
  4. Aggie

    Aggie Member

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  5. Donald Miller

    Donald Miller Member

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    I recently printed a Stouffer 21 step tablet (densities of .15 to 3.00)on Azo to determine the paper characteristics of both grades two and three Azo. Using my enlarger (Saunders 4550 XLG with 250 watt light source) with the lens aperture at F5.6 my times were six and one half minutes for grade two and eight and one half minutes on grade three. (Grade three requires approximately 33% more exposure than grade two by my tests).

    This paper is approximately 1/25 the speed of conventional silver enlarging paper. (paper speed 6 compared to 150 for Kodak variable contrast). That is why most use a reflector flood lamp to expose Azo. Hope that this gives you some idea.
     
  6. PaulH

    PaulH Subscriber

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    I use my D2, which has the equivalent of an Aristo Hi-Intensity Cold Light Head. I take out the negative carrier, lens and lensboard and crank the bellows all the way up. I set my enlarger at 24" above the paper. When I do the Souffer Tablets , it requires an exposure of 20 seconds to get about the same results that Don does. Hope this is helpful.
     
  7. Aggie

    Aggie Member

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  8. fingel

    fingel Member

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    I use a 250watt halogen flood light and get times of about 5-8 seconds.
     
  9. Silverpixels5

    Silverpixels5 Member

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    Hmmmmm...l think I may be using the speed of the paper as an idication of how long I'll expose it. This will put my exposure in the minutes rather than seconds. If I find that it overexposes then I'll do a step every 5 seconds. Hopefully I'll get it the first time. Thanks for all the help! :smile:
     
  10. Tom Duffy

    Tom Duffy Member

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    I concur with Don, with my Saunders 4x5, my print time is 12 min at f8. better to buy a reflective bulb. my times with a 75watt reflector bulb 2 feet over the paper is about 60 sec.
     
  11. Silverpixels5

    Silverpixels5 Member

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    I would seriosly consider getting a reflector bulb but i would have no where to suspend it. My bathroom is my darkroom and my printing area consists of a 3/4" piece of plywood over my bathtub, which would mean I would have to suspend the light from above the tub...lol. I currently use a besseler 23C. I have an Omega D5, but can't really fit it in the bathroom/darkroom. Once I move, i'll have a dedicated darkroom where I can make a contact printing area, but until then I'll have to make use of my good ol' 23C. I"ll test the paper tomorrow and post the times.
     
  12. Aggie

    Aggie Member

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  13. Silverpixels5

    Silverpixels5 Member

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    Thanks for the tip. I'll make a trip to Home Depot and see what they have. What size lamp should I be looking for?
     
  14. doughowk

    doughowk Subscriber

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  15. Aggie

    Aggie Member

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  16. Donald Miller

    Donald Miller Member

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    The only problem with clipping a reflector housing to a towel bar is that if the printing frame is not directly below the light output it will not be evenly lit and the light fall off could be a problem in achieving a good print. (The effects of light intensity are a function of distance.)

    I use as much as 300 watts of light and as little as 150 depending on the negative. Sometimes on really dense negatives 300 watts is required to achieve manageable times. Other times 150 watts is needed to allow adequate dodge times. I don't use a reflector housing...I use a reflector flood lamp.

    Michael Smith uses a 300 watt reflector flood on his prints. I would imagine that with 4X5 Azo paper that you wont be doing a lot of fine burning or dodging.
     
  17. Michael A. Smith

    Michael A. Smith Subscriber

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    There is no problem doing fine dodging and burning with a 4x5 print. Same as a bigger print in all regards.

    If you only have a few sheets of paper, 5 seconds seems awfully short for intervals for a test strip, unless your negative is on the thin side. At 5 second intervals you risk all strips being too long or too short, which would leave you nowhere.
     
  18. Silverpixels5

    Silverpixels5 Member

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    I just developed a few sheets of the Azo I had with very good results. For my ABC negs, exposure times were about 5 minutes, and then developed in Agfa Neutol WA. This is really exceptional paper because it looks as if I could walk into one of the prints. I also tried one of my negatives developed in Rodinal and my exposure times were around 1 minute..although the negative was slightly thin to begin with. I'm really pleased with this paper. Its 30 yrs old and prints better than any of my current papers. I should be placing an order from Michael in the near future. :smile:
     
  19. Silverpixels5

    Silverpixels5 Member

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    I went to Wal-Mart today and got a 3 dollar clamp light with a 9 inch refletor and a 65 watt plant light. I got the plant light instead of a regular flood light b/c I've heard that azo is more sensitive to blue light and the plant light has an ever so slight blue tint. The light was clipped to my shower curtian rod about 4 feet above my printing frame. This setup cut my times from 5 minutes down to 10-15 seconds, and I've very pleased with the results. Just wanted to give an update, and mention the use of the plant light. :smile:
     
  20. Aggie

    Aggie Member

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    great idea, I may switch to the plant light bulb too. Thanks for the info.
     
  21. Donald Miller

    Donald Miller Member

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    Thanks for sharing your experience with the plant light. Azo is primarily sensitive to light in the near band UV range. It's peak spectral response occurs at 350nm and drops from there to appr. 460 nm. Most of us use reflector floods which have virtually non existant UV outputs and the output from these lamps that is higher then blue is largely wasted. So your plant light is probably much more efficient. The lowest wattage that I have been able to utilize with a reflector flood is 150 watt (Pyrocat HD negatives) and more normally 300 watt (with ABC Pyro negatives).
    I have heard that the more current Azo emulsion is of differing contrast then the earlier emulsion which you indicated that you had. I would be interested in learning your experience with newer emulsion and the plant light. I would appreciate it if you would share your experience in that regard when you have have had time to evaluate it.
     
  22. Ed Sukach

    Ed Sukach Member

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    A "Sunlamp", used for tanning purposes, might be even more efficient. Their reson for being is UV emanation.
     
  23. Donald Miller

    Donald Miller Member

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    Ed, I agree, the problem is that while Azo is sensitive to UV when purer forms of UV are utilized the paper exposes more rapidly (too rapidly in most cases for effective burning and dodging).

    I have thought that perhaps a lower output UV source might really be beneficial for Azo. The primary reason would be that the proportional stain that Pyro developers impart to the negative act as additional density to blue light and also additionally to UV light as well.

    In the case of blue light the Pyro stain may add the equivalent of appr. .20 units of density at a silver density of 1.20. Effective blue light transmission density then becomes 1.40.

    The proportional stain adds additional density beyond the blue light effect to UV transmission. In the case above, for example, it may add another .20 density units to UV transmission. Effective UV transmission density may then be on the order of 1.55 to 1.60.

    As the negative silver density increases the proportional stain effect to both blue and UV transmission increases.

    The reason that I think that a lower output UV device may be beneficial to Azo users is that it would enable greater expansion of the contrast range of the camera negative then what reflector floods or even plant lamps would enable. Lower contrast films would then perhaps be more useable for Azo. Certainly all films would exhibit the ability to expand density range beyond what the blue light effect alone would be when using proportional staining pyro developers.

    With your experience in this field, Ed, I imagine that you have ideas on how to effect UV usage albeit at a more manageable level. I would appreciate your thoughts on this. Thanks for your input.
     
  24. sanking

    sanking Restricted Access

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    If you look at Kodak Technical Publication G-10 on AZ0 you will find a spectral sensitivity chart. The direct link is http://www.kodak.com/global/en/professional/support/techPubs/g10/g10.jhtml?id=0.3.8.26.44.14.3&lc=en

    As Donald pointed out, AZO is very sensitive to light in the near UV and Violet range, from about 350 to 425 nanometers. One could no doubt expose AZO with the same UV lights that we use with alternative processes such as pt/pd but exposing times would be very short, probably too short to be practical with AZO.

    The plant light seems like a very good idea because these lights put out some UV light but not nearly so much as the lights we use with alternative processes.

    Also, in response to Ed's note about using a sunlamp, it is true that these lamps put out a lot of UV light. However, they appear to have been taken off the market because I have not seen one for sale in years.

    Sandy