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  1. #21

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    So just to nail this one down. You have taken away the ND filter, reverted to an aperture of f45, found the correct combo of Y and M filters and have achieved prints with good colour balance?

    Presumably you also use UV and IR filters.

    Just as a matter of interest what combo of Y and M did it take to get good balance and do you now find that simply removing Y and M filters produces a markedly red cast as it should?

    Thanks

    pentaxuser

  2. #22

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    Quote Originally Posted by pentaxuser View Post
    So just to nail this one down. You have taken away the ND filter, reverted to an aperture of f45, found the correct combo of Y and M filters and have achieved prints with good colour balance?

    Presumably you also use UV and IR filters.

    Just as a matter of interest what combo of Y and M did it take to get good balance and do you now find that simply removing Y and M filters produces a markedly red cast as it should?

    Thanks

    pentaxuser
    I have a UV filter, but no IR filter. The filtration is still very low, between 10M 10Y to nothing, but I believe that can probably be accounted for by the yellowness of the light from my condenser enlarger, and also possibly the IR light I've not filtered out. I've used a different condenser enlarger with similar results before. In any case, I'm getting perfect prints.

    Quote Originally Posted by RPC
    But it still seems strange that prints would come out cyan with no regular filtration. Just think how much regular filtration it would take to do this...typically 50-75 units of magenta and yellow just to balance it, and then even more to make it cyan. Even with IR and UV hitting the paper, is such an effect really possible? It does not happen for me. And if the ND filter looks even close to what a ND filter would look like it, how could it have such an effect?

    RPC
    I should probably mention that the ND filter I was using was a plastic Cokin filter, which are somewhat known to be kind of crappy. I once owned a small cokin filter system, but sold it because it wasn't really that great. I only kept the ND filter because I found it useful in the darkroom.

  3. #23
    RPC
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    IR stimulates the red-sensitive layer of the paper, making it more cyan. With the ND filter in the enlarger you might get some blockage. With the filter out, you would get no blockage and the print would be more cyan. Yet you have the reverse. Weird...

    RPC

  4. #24
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    I guess you still don't see it. The ND appears to be blocking the visible portion and lets more IR through than normal thus giving the print a cyan cast.

    No proof, but that is what it sounds like.

    PE

  5. #25
    RPC
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    Yes, I understood. It is just that my experience with both IR filters and ND filters have not had near the magnitude of difference he experienced, but I conceed his circumstances could quite different.

    RPC

  6. #26
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    No on will actually know for sure without a spectroscopic examination.

    I am surprised, but I have a probable explanation that will work for now. From your post, it seemed as if you did not understand that possible answer. I am sorry for the confusion and did not mean anything personal by my post.

    PE

  7. #27

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    Yes, and a pretty good probable explanation I suspect too.

    I don't know all the details, nor have the time to learn them, but look at:

    http://photonius.wikispaces.com/ND+gradient+filters

    about mid page at eg Cokin A 121 and you will see that
    their filter's ND effect did/does not extend all the way into tomorrowland.

    Ray
    Last edited by Ray Rogers; 06-12-2010 at 02:33 PM. Click to view previous post history.

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