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  1. #1
    Regular Rod's Avatar
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    Reciprocity Table for EKTAR 100?

    Can anyone point me in the right direction for an EKTAR 100 reciprocity table please?

    Thank you.

    RR

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    I am not so sure there will be one, but if there is There will be someone along with some sort of reply

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    For a starting point, longer than 1 second, add 1 stop. Longer than 1 minute, add two.

  4. #4
    LJH
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    I don't think that there is an "official" table. Kodak suggests that you run your own tests with exposures longer than 1sec.

    Have you searched for people's results on this? I had a quick look and there is a fair bit of anecdotal information out there (including on this site).

  5. #5
    Regular Rod's Avatar
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    Quote Originally Posted by TheFlyingCamera View Post
    For a starting point, longer than 1 second, add 1 stop. Longer than 1 minute, add two.
    Yes but what if the stop is pre-decided for the exposure and the indicated exposure is more than a minute?

    ILFORD provides a useful graph for customers. Kodak it seems does not. Maybe they don't test their products. It's okay for Kodak to say "Make your own tests..." They aren't the ones buying the film!

    RR

  6. #6
    Regular Rod's Avatar
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    Quote Originally Posted by LJH View Post
    I don't think that there is an "official" table. Kodak suggests that you run your own tests with exposures longer than 1sec.

    Have you searched for people's results on this? I had a quick look and there is a fair bit of anecdotal information out there (including on this site).
    I'm really looking for a graph or table as per ILFORD's customer service. Kodak could learn from the once smaller company...

    RR

  7. #7
    LJH
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    Quote Originally Posted by Regular Rod View Post
    I'm really looking for a graph or table as per ILFORD's customer service.
    The Ilford charts are pretty loose IMO. You're still guestimating times when the X and Y don't intersect on a given time combination. For instance, how long is the required exposure with an indicated 2 second exposure on this chart?

    Run some test. You don't need to use much film; strip tests using the dark slide will give you a pretty good starting point. Ektar's pretty forgiving, so your results might not be as varied as you currently think they'll be.

  8. #8
    Regular Rod's Avatar
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    Quote Originally Posted by LJH View Post
    The Ilford charts are pretty loose IMO. You're still guestimating times when the X and Y don't intersect on a given time combination. For instance, how long is the required exposure with an indicated 2 second exposure on this chart?

    Run some test. You don't need to use much film; strip tests using the dark slide will give you a pretty good starting point. Ektar's pretty forgiving, so your results might not be as varied as you currently think they'll be.


    That would be 5 seconds
    . You simply look across to the numbers on the right hand side. You can make the chart easier to use by printing it off with a grid.


    I have used the ILFORD charts for a long time and they have never let me down.


    The EKTAR 100 film and processing is far too expensive for me to squander on testing that Kodak should have done for us, the paying customers, in the first place.


    What did you do when you were finding out that EKTAR 100 was pretty forgiving?


    RR

  9. #9
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    Quote Originally Posted by Regular Rod View Post
    Yes but what if the stop is pre-decided for the exposure and the indicated exposure is more than a minute?

    ILFORD provides a useful graph for customers. Kodak it seems does not. Maybe they don't test their products. It's okay for Kodak to say "Make your own tests..." They aren't the ones buying the film!

    RR
    An f-stop in this context is a quantity of light. It can be achieved by opening the lens further or it can be achieved by adding time. I prefer adding time when dealing with long exposures. So if the indicated time is more than one second but less than one minute, double the time. If the time is more than one minute, double it and double it again - i.e. if the meter says 1 minute, then give it four. if it says 15 seconds, give it 30 seconds. This is a fairly stable formula for most color negative emulsions. This is probably why Kodak has not provided a chart for Ektar. Besides, once you get into these extremely long exposures, precision becomes a relative thing and is fairly irrelevant. What you get is largely a matter of taste and need, not a matter of accuracy.

  10. #10
    Regular Rod's Avatar
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    Quote Originally Posted by TheFlyingCamera View Post
    An f-stop in this context is a quantity of light. It can be achieved by opening the lens further or it can be achieved by adding time. I prefer adding time when dealing with long exposures. So if the indicated time is more than one second but less than one minute, double the time. If the time is more than one minute, double it and double it again - i.e. if the meter says 1 minute, then give it four. if it says 15 seconds, give it 30 seconds. This is a fairly stable formula for most color negative emulsions. This is probably why Kodak has not provided a chart for Ektar. Besides, once you get into these extremely long exposures, precision becomes a relative thing and is fairly irrelevant. What you get is largely a matter of taste and need, not a matter of accuracy.

    Thank you. I will give that a try.


    RR

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