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Thread: AZO Lightsource

  1. #21
    bmac's Avatar
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    Quote Originally Posted by Donald Miller
    What is the peak density on your negatives? What is your density range on the negative? If the negatives are overexposed and then developed to the proper density range the printing exposure times will be lengthened.
    You've got me!

    The printing session I did the other night was a simple film speed test. I set up a Kodak Grey Scale target and a grey card, set my meter for 400 (it was TMY) and did exposures at the exposure reading, then +1 and then +2. I did three sheets at each exposure.

    I then split them into three batches.

    Did one for the time Sandy gave me for Pyrocat and TMY, one at -20% and one at +20%.

    There is the distinct possibility that I over exposed the AZO, but with my visual densitometer (my eyes ) I am seeing that with my materials and my processes the negative exposed for Sandy's time with +1 exposure (efs 200) is giving me the negative with the best tonal range from pure white to maximum black.

    Not sure where to go next...
    hi!

  2. #22

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    I have thought about printing with my grow lights. I could get a tan at the same time. Actually, in the reflectors I have, there is no exposure to the bare bulb at all, it is recessed a fair bit. All of the light is reflected down. They would be a good light source because the reflectors are also designed to give even illumination over a specific area. I have the brightest room in the building.

    I was not recomending the use of the 1000 watt bulbs but was thinking there are really cheap ways of getting specialty light bulbs. The only exception are BL bulbs.
    Technological society has succeeded in multiplying the opportunities for pleasure, but it has great difficulty in generating joy. Pope Paul VI

    So, I think the "greats" were true to their visions, once their visions no longer sucked. Ralph Barker 12/2004

  3. #23

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    Quote Originally Posted by bmac
    You've got me!

    The printing session I did the other night was a simple film speed test. I set up a Kodak Grey Scale target and a grey card, set my meter for 400 (it was TMY) and did exposures at the exposure reading, then +1 and then +2. I did three sheets at each exposure.

    I then split them into three batches.

    Did one for the time Sandy gave me for Pyrocat and TMY, one at -20% and one at +20%.

    There is the distinct possibility that I over exposed the AZO, but with my visual densitometer (my eyes ) I am seeing that with my materials and my processes the negative exposed for Sandy's time with +1 exposure (efs 200) is giving me the negative with the best tonal range from pure white to maximum black.

    Not sure where to go next...
    Brian,

    I would have to agree that Sandy's tests are undoubtedly accurate. A plus one development would normally be accompanied with the same film speed as a normal exposure (possibly a 1/3 stop increase in film speed...that would indicate an EI 400 to EI 500). I noticed that you indicated an EFS of 200 for a plus one development exposure. Am I understanding that you are adjusting your meter to 200 for exposure calculations? That would seem to me to be overexposing the film by about one stop. Are you using incident or spot metering?

    Normally film speed (for exposure calculations) would be adjusted to a higher EI for expansion development and adjusted to a lower EI for contraction development.

    If the film is actually being rated at 200 then the overall density would become greater and lead to increased printing times. If, instead, you are rating the film at 400 and using spot metering and placing your shadows on Zone IV then you are also effectively derating the film below the 400 speed since the 400 EI would be based on a Zone I exposure. This increased low value density will have a detrimental effect on obtaining the appropriate density range (contrast) on the negative.

    I don't know that any of the above considerations apply to your situation. I am just mentioning them in the event that they may be. I have no experience with a 65 watt grow light. Therefore I don't know what your printing exposure times would most likely be.

  4. #24
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    I don't know where other people are getting their 300 watt light bulbs, but I got mine from McMaster-Carr (www.mcmaster.com). It was under $30. A 200w bulb from the hardware store didn't cut it for me since my negatives are really dense. I don't do the BTZS stuff.

    If you do get a bulb from McMaster, it is a R-40 bulb, but it has a larger than normal base. The part that screws in the socket is nearly twice the diameter. I didn't know this when I bought it. After some research, and a call to my father-in-law (who is an electric engineer), I found this is called a "mogul" bulb. I just went to the local commercial lighting place and got a socket. Adapters are available that screw into a regular socket and then accept a mogul bulb. They seem affordable at $15.

    www.bulbman.com didn't have any 300w r-40 bulbs except for the heat lamps. They did have replacement bulbs for the Thomas Duplex safelight, though. And they are $45 or so.

    -Greg

  5. #25

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    ? This is what I use. Cost around $30. (I hope I got the image here. I'm going to post it and see what happens.)
    Attached Thumbnails Attached Thumbnails 300www.jpg  
    Paul Hamann

  6. #26

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    Gee, it worked! Don't know where the ? came from, though. I got mine from a local electrical supply store.
    Paul Hamann

  7. #27
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    Don,

    I'm doing normal development (Sandy's times) with +1 stop of exposure. Using an incident meter. The negatives dont look over developed or over exposed to my untrained eye.
    hi!

  8. #28

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    Quote Originally Posted by bmac
    Don,

    I'm doing normal development (Sandy's times) with +1 stop of exposure. Using an incident meter. The negatives dont look over developed or over exposed to my untrained eye.
    Brian,

    As I said, I don't have experience with the lamp that you are using. I use 300 and 150 watt reflector flood lamps. I believe the plant grow lamp does emit some UVA whereas the reflector flood lamps emit blue and virtually no UVA so it would seem that the plant grow lamp would require less wattage since Azo is most sensitive to UVA light. However this is conjecture on my part.

    It would seem to me, though, that the one stop additional exposure that you are giving above Sandy's tests would double your print exposure times.

  9. #29
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    I aplan on doing another printing session this weekend and will try out a couple other lights I have (a 200w photo flood, and a 120w R40) and will report back.
    hi!

  10. #30

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    Quote Originally Posted by bmac
    You've got me!


    There is the distinct possibility that I over exposed the AZO, but with my visual densitometer (my eyes ) I am seeing that with my materials and my processes the negative exposed for Sandy's time with +1 exposure (efs 200) is giving me the negative with the best tonal range from pure white to maximum black.

    Not sure where to go next...
    In determing exposure with your meter and metering system and making exposures with your own lens/shutter combination you have taken the tests to the area of E.I., or what I call the personal exposure index. At this point what you see is what you get and if your system tells you that the best EI for Tmax 400 with your metering system and lens/shutter combination is 200 then that is what is best for you.

    In my own case I base exposures on an incident light reading in the shadows and rate TMAX 400 at EI 1200 and get good shadow detail. Shadow density would be about the same if I were to base my exposures on an average of two incident readings, one in the shadows and another in the highlights, and halve the EI to 600.

    In most cases personal EI figures have limited meaning to others, primarily because of the wide variety of metering methods in use, but also because of variations in shutter speeds and lens apertures.

    Sandy
    Last edited by sanking; 05-26-2004 at 03:32 PM. Click to view previous post history.

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