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  1. #1
    BetterSense's Avatar
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    Double exposure times for high-contrast filters? Not mine.

    I got a full set of Ilford MG under-lens filters recently with no box or instructions. I always heard that for filters above 3.5, you were supposed to double the exposure time. I don't see that at all when I use mine. From right to left, grade 2.5 at 10s, grade 5 at 10s, and grade 5 at 20 seconds.

    weird?
    Attached Thumbnails Attached Thumbnails contrast.jpg  

  2. #2
    ic-racer's Avatar
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    I see your point. I also don't see much contrast change between the 2.5 and the 5, so perhaps your 5 filter has faded.

    Here are the instructions if you have not already located them: http://www.ilfordphoto.com/Webfiles/...0201152306.pdf

  3. #3
    RalphLambrecht's Avatar
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    Please remember that exposure changes for contrast filters are designed for a print density of 0.6. Any other density needs a different exposure factor.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  4. #4
    ath
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    Ralph is of course right. And additionally every set of filters is designed for a specific paper. Other papers sometimes behave significantly different.
    Regards,
    Andreas

  5. #5

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    Based on what the OP has said, it is safe to assume that the filters were secondhand. On the recent Ilford tour I think that Simon Galley hazarded a guess that the filters need replacing every 20 years or so. If the problem is fading of the grade 5 filter, how does he go about ascertaining whether this is the case? Once he establishes whether fading of the grade 5 filter is the problem or not he can then move on to a solution such as replacement or further investigation as to other causes.

    I cannot help here as my knowledge is nowhere near good enough but so far I feel that collectively we haven't helped him get much closer to a solution either.

    pentaxuser

  6. #6
    RalphLambrecht's Avatar
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    I think pentaxuser has a point. ic-racer made the point that the filters may have faded. BetterSense needs to do a contrast test for the set of filters in question to see if the contrast does change with each filter. If conducted with a simple step tablet (Stouffer), the actual contrast delivered by each filter and the exposure factor required for a filter can be determined.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  7. #7
    Nicholas Lindan's Avatar
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    The constant-exposure density changes with the paper and even with the developer and toner:

    • MGIV FB: 0.45 OD
    • MGIV RC: 0.55 OD
    • MGIV FB WT: 0.9 OD
    • MGIV FB WT/A130/Se 1:9 to completion: 1.3 OD
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  8. #8
    RalphLambrecht's Avatar
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    Quote Originally Posted by Nicholas Lindan View Post
    The constant-exposure density changes with the paper and even with the developer and toner:

    • MGIV FB: 0.45 OD
    • MGIV RC: 0.55 OD
    • MGIV FB WT: 0.9 OD
    • MGIV FB WT/A130/Se 1:9 to completion: 1.3 OD
    Nicholas

    What is this?
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  9. #9
    BetterSense's Avatar
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    I was using MGIV RC glossy paper of uncertain age. I bought the filters used, and I don't know how old they are. I also got some Kodak variable-contrast filters. In the interest of not wasting paper I would like to test the effects of these filters, but I'm not sure how to proceed. I do have some new MGIV satin paper. I don't have a step wedge, but I have a Kodak Projection Print Scale.

  10. #10
    RalphLambrecht's Avatar
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    Quote Originally Posted by BetterSense View Post
    I was using MGIV RC glossy paper of uncertain age. I bought the filters used, and I don't know how old they are. I also got some Kodak variable-contrast filters. In the interest of not wasting paper I would like to test the effects of these filters, but I'm not sure how to proceed. I do have some new MGIV satin paper. I don't have a step wedge, but I have a Kodak Projection Print Scale.
    The Kodak Projection Print Scale is not good enough. You either need a step tablet (stouffer) or a timer (an f/stop timer with 1/3 stop increments would work well). Anyway, the step tablet does it all in one exposure, any timer will require multiple exposures, which is frustrating.

    I suggest to invest a few $ and call Stouffer. You can use it for many tests, not just this one.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

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