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  1. #31

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    Quote Originally Posted by Kirk Keyes
    I'll look into the second part of your post later.

    Kirk
    Sandy - I flipped through my Wratten filter book, and there were no good filters fo this.

    However, I do have some dichroic, narrow bandpass filters that I picked up last year. They are not mounted in retaining rings, just the glass. They are about 3 mm thick and either 12 or 25 mm diameter. I have them for several wavelengths - from memory they we something like 365, 385, 400,... If you would like to borrow one to try, let me know.

    The main problem I see is that for the shorter wavelengths, the tungsten bulb in the densitometer if going to be loosing energy in those wavelengths, so that even if the photocell is still sensitive (which it may well be), then you will have a noisier signal and less precision in your readings.

  2. #32
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    May even need a bulb in a special UV transmitting envelope.
    Gadget Gainer

  3. #33
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    Quote Originally Posted by sanking
    Well, I disagree a bit on this. I find the densitiometer very useful in making initial decisions with a new negative about printing speed and the type of contrast control that will be required. I measure the shadow values, which tell me how long exposure should be, and then the highlights. Substracting the shadow from the highlights gives the negative DR which I can then used to determine how to control contrast.

    If you are working with an alternative process such as platinum this way of working can save a person a lot of time and expense over trial and error. I know that some people claim that they can just hold a negative up to the light and immediately know how long to print and what the contrast will be, but unfortunately I am not that talented.

    Sandy
    Yes, but without a densitometer you can still print the step wedge and the negative of it tohether on the paper you plan to use and count the visible steps of each. Divide one by the other to get DR. Even if you have a densitometer, you may not be able to match the response of VC paper to pyro negatives.

    I, of course, made my own densitometer. It is of a type that I can use it on the enlarger easel. I can calibrate it to use as an exposure meter for prints, or to measure projection density, and I can change the sensor to read reflection density. It has a digital readout.

    Don't look at me that way. I also grow my own cane for oboe reeds and made my own gouging machine for cutting the cane to the proper thickness. Saved me $1500 30 years ago. Who knows how much that is worth now?
    Gadget Gainer

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