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  1. #21
    gainer's Avatar
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    Quote Originally Posted by Kirk Keyes
    Pat - can you give some links to the digital panel meter you like. Anything with a serial out would be nice too. And how about some recomendations on the phototransistor? Some place like Digikey would be cool.

    Does your enlarger have a voltage stabilizer on it? How about replacing the lightsource with something that could be better stabilized, led or laser perhaps. We don't need something that covers a wide area of the neg. A lot of intensity in a small area is fine. A red or green laser pointer with a bit of opal glass would make a nice light source that one could place right up against the portion of the neg that one was interested in.
    It's been a long time and I have had an attack of encephalitis in the meantime, but I found a catalog of Circuit Specialists from 1998. If they are still around, they are at www.cir.com. You will want a meter with LED readout rather than LCD. They are cheap for 3 1/2 digits, which will do quite well for this purpose. Who measures densities above 19.99?

    My enlarger uses an 82 volt bulb, obtaining that from half wave rectification without filtering. I have been laying off for some time to build a regulated DC supply for it. For most of my uses I can put up with small fluctuations, so I keep putting it off.
    Gadget Gainer

  2. #22
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    I forgot to address the question of serial output. These panel meters are essentially timers that count the number of time increments it takes to integrate a step inut until the signal voltage equals the integral. I don't think any of them will have a point where the serial or even parallel digital output is available. the whole circuit is integrated and provides out put directly into a 7 segment display.

    I know there are available integrated A-D converters, and if you are using the simple log amplifier circuit its output will be the analog input for the A-D converter as well as the panel meter..
    Gadget Gainer

  3. #23
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    Sorry to be so pedestrian in this discussion, but the film and developer come into play at some point. Once this device for measuring has been created, I will be very interested in seeing which film-developer combination ranks "first". Too many variables to list, too many films and developers, I know, but it will be interesting to see how the latest offering in tabular grain film rates against the old efke 100 or tri-x. Hopefully such a list will be possible. tim

  4. #24
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    This is kind of interesting. And goodness knows I like to watch ANYBODY work.

    I understand this is taking place in the APUG Province of The Back of Beyond, somewhere behind the smokehouse.

    But I'd love to examine the premise of this exercise and how it relates to taking pictures and hanging them on the wall.

    The over Gratuitous Technicalisation of Silver Based Imaging has been a concern of mine for a long time. I fear there is a great danger that, said and done, the Test will simply Test the Testers rather than the intended process.

    I appreciate the apparently 'seat of the pants testing' protocol used by garden variety photographers [of imaging a contrasty target of known contrasts and dimensions for viewing] suggests the potential for error. I also acknowledge that it may be desirable to achieve more detailed information.

    At the same time, I DO wonder what that higher layer of resolution this discussion hopes to achieve.

    Of possibly more relevence, does the process suggest a protocol so refined that it will be unrepeatable and hence yield invalid results ?

    In particular I'm concerned that the results will have micro-resolution that has less relevence to image - making than our current slap-dash protocols.
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  5. #25

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    Quote Originally Posted by df cardwell
    Of possibly more relevence, does the process suggest a protocol so refined that it will be unrepeatable and hence yield invalid results?
    One of my rules is that the testing protocols must be repeatable and capable of generalization. These may prove to be unrealizable goals. If so, that is an answer - of sorts.

    Quote Originally Posted by df cardwell
    In particular I'm concerned that the results will have micro-resolution that has less relevence to image - making than our current slap-dash protocols.
    Yep, that's always a possibility. But hopefully the results will lead to better understanding and predictability of the process.
    Tom Hoskinson
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  6. #26
    df cardwell's Avatar
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    Tom

    Good.

    Do you know what the results will look like ?
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  7. #27

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    Quote Originally Posted by df cardwell
    Tom

    Good.

    Do you know what the results will look like ?
    The proposed design will use Edmunds chrome-on-glass Tri-Bar Targets and Stouffer step wedges as test patterns for contact printing onto film.

    We will be looking for repeatable and predictable differences in microdensity based on varying agitation, pH, concentration, developer buffering, etc for a film/developer combination.

    To design efficient test plans, I have proposed the use of Statistical DOE ( Design of Experiments) methodology.

    The original APUG thread asked the question in reference to Pyrocat-HD with stand development versus various agitation schemes and it will be one of the developers considered. Several B&W films will be utilized.

    Pat Gainer is currently investigating the properties of an Amidol/Ascorbate/TEA film developer with several films.
    Tom Hoskinson
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  8. #28
    df cardwell's Avatar
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    Yes, Tom

    I follow that.

    I'm not asking about process, or methodolgy.

    I'm not asking to predict the outcome.

    I'm asking if you can describe what the results will look like.
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  9. #29

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    Quote Originally Posted by df cardwell
    I'm asking if you can describe what the results will look like.
    The primary hypothesis is that there is a difference in image microcontrast in negatives stand or semi-stand developed in Pyrocat-HD (or other developers). This hypothesis is based on visual comparisons of negatives developed by the stand or semi-stand method compared with identical negatives developed with conventional agitation.

    The results should show that there are (or not) quantifiable differences in image microcontrast related to the agitation methods.

    If there are quantifiable differences, then the next questions on the table relate to the reasons for the differences, with the purpose of predicting, controlling and optimizing them.
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  10. #30
    gainer's Avatar
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    Quote Originally Posted by Tom Hoskinson
    The primary hypothesis is that there is a difference in image microcontrast in negatives stand or semi-stand developed in Pyrocat-HD (or other developers). This hypothesis is based on visual comparisons of negatives developed by the stand or semi-stand method compared with identical negatives developed with conventional agitation.

    The results should show that there are (or not) quantifiable differences in image microcontrast related to the agitation methods.

    If there are quantifiable differences, then the next questions on the table relate to the reasons for the differences, with the purpose of predicting, controlling and optimizing them.
    I'm sure you have or will consider this, but I bring it up anyway. There will no doubt be objective difference in the adjacency and other effects of agitation and developer constitution. There will also be subjective differences among viewers, and certainly a particular objective edge characteristic enlarged from 35 mm will not be either objectively or subjectively the same as a contact print from an 8X10 negative.

    I used to design the kind of experimental plan you want to use. I hope I don't ever have to do the grunt work to make this one happen. It will be more like a barrel than a can of worms. It's bad enough when you are dealing with a multivariate linear process. There are times when serendipity is not such a bad thing. What I mean is, I hope you get lucky.
    Gadget Gainer

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