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  1. #41
    Photo Engineer's Avatar
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    Kirk;

    I have no panchromatitc dyes. Sorry. I have blue green and red.

    PE

  2. #42

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    Kirk- Heck! we both coulda gone through 4 years of Accounting School and become CPAs by now ! But how much fun and challenge would that have been?
    Bill

  3. #43
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    Quote Originally Posted by Photo Engineer View Post
    Chris;

    With few exception (Erythrosine and Chlorophyll being two I can name OTOMH), emulsion sensitizing dyes have positively charged Nitrogen atoms in them.

    See attached. There is a resonance plus charge carried by one of the Nitrogens as the electrons resonate. Compare with Rhodamine.

    PE
    Ok Ron, here is rhodamine 6G and B's structure. And I included the one you posted, which is....? Are those just "cyanines"?

    This is a completely foreign language to me, but I'd like to learn it. What do you call these kinds of diagrams?
    Attached Thumbnails Attached Thumbnails Rhodamine 6G.JPG   Rhodamine B.JPG   Sensitizers.JPG  
    If you are the big tree, we are the small axe

  4. #44
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    Chris;

    These are structural diagrams of organic chemicals. The first two have charged amines in side chains, and the "real" SS dyes have the charged nitrogen in a ring structure called a heterocycle. There is a huge difference between the two types of structure regarding the distribution of charge (electrons) and in the latter case it allows the dye to bind to the surface of the silver halide crystal and to transfer energy from light to the crystal.

    The former two may or may not, but even if they do, it would probably be inefficient. Erythrosine is more similar to the former two in a way, and it is quite inefficient in energy transfer and so it is more difficult to use in some cases.

    PE

  5. #45
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    Here's Erythrosine just for reference.

    Ok, so if these non-ideal S.S.D. (spectral sensitizing dyes) aren't as efficient, how exactly would that manifest itself? For starters, let's pretend we have an experimental silver emulsion that is completely unsensitized and it has a speed of 100.

    The 100 would apply to blue. Presumably green would be much lower (by a factor of what?) and red lower yet.

    So if we remake the exact emulsion but add dye X as a "final" (is that when you add SSDs?), how would that effect our distribution of speeds in the blue, green and red portions?

    I'd like to roughly understand the practical differences between SSDs like erythrosine, congo red, etcetera (old-school sensitizers) and the ideal cyanine dyes.

    I realize this is a dense (in more ways than one!) post.
    Attached Thumbnails Attached Thumbnails Erythrosine.JPG  

  6. #46
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    There are many results possible Chris.

    You may end up with no speed at all, matched green and blue speeds or reduced blue speed and some green speed. This includes all variations in between. The answer is "it depends"!

    Sorry, too many imponderables. And even if it works, how will you measure it? There are ways, but it takes either equipment or special step wedges.

    PE

  7. #47
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    If I pay you $10 will you just tell me what I want to hear?

    Ok, so if you add too much SSD, it becomes a desensitizer right?

    As for measuring, didn't they use prisms basically to spread out the light? How do they make those wedge spectrograms? It seems simple in theory, but maybe it's harder than it sounds to get an even distribution of spectral colors and with a gradual fall-off.
    If you are the big tree, we are the small axe

  8. #48
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    Yes, most SSDs are sensitizers and desensitizers depending on concentration. That is why I have been doing all the hard work for you guys getting it right!

    At $100 / gram, you can go broke fast.

    And, a monochromator is what you need and what you have described in your post Chris. It is a prism or diffraction grating that splits white light into a rainbow.

    PE

  9. #49
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    What about "Mowrey's Fantastic Panchromatic Sensitize-All" - just add two drops per mole Ag.

    There's a winter project for you Ron
    - Ian

  10. #50

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    That is why I have been doing all the hard work for you guys getting it right!

    At $100 / gram, you can go broke fast.



    PE[/QUOTE]

    PE,
    I guess that I have been just pounding my Pud all this time!? Try $150/gram. That is what I paid + a "Convenience Fee". I have requested a new quote. But I am sure that the price has not gone down.



 

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