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  1. #1

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    Test Strip Results.

    Well, my first night in the darkroom was fun but yeilded no results. Basically my test strips were mostly black. I set my enlarger to 8x10 size and did a whole sheet of paper with the lense wide open. No negative just the carrier, #2 filter. This strip had different grades on it but the center had a giant black rectangle in the middle. I did this one at 5 sec. intervals. I then left the enlarger at the same height and cut a piece into quarters. The first three were black. I progressively made the aperture smaller with each strip. the last one was done at f11. I put in a unexposed, but developed piece of film and focused. I did this strip at 2 sec. intervals. I basically got three shades before black. The first 2 sec exposure yeilded middle gray. Unexposed paper came out paper white. I'm using MG IV RC w/ Ilfords MG dev. which was 70 degrees. The chem side seems fine. Print appeared after about 10 seconds. Dev'd for one minute. Kinda stuck. I'm guessing, but 8 seconds to black is too short? what am I doing wrong?
    TIA

  2. #2
    ann
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    If you are attempting to find min time for maxim black you will need to be stopped down to f8 or f 11 and use a blank negative or the rebate of processed film. Do a step wedge across the paper at 3 sec intervals. Process for 90 secs.

    A test without a negative doesn't mean much. Leave the fstop constant and change the time, not the other way around. i.e. don't start wide open and stop down.

    8 secs is too short.

    Did you make any other prints? What is the light source? Cold light heads tend to use more time than condensor heads.

  3. #3
    Ole
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    Making the strip in stops instead of a fixed second interval is often quicker:
    Try 1, 2, 4, 8, 16, 32 seconds.
    -- Ole Tjugen, Luddite Elitist
    Norway

  4. #4
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    Are you perhaps confusing test strips with pre-flashing paper?
    [size=1]the all new darkplanet photoblog[/size][size=1]
    [/size]

  5. #5
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    Test strips

    Dear Mr. Rat,

    I think you may be getting a bit too technical in your approach. The test strips you are making are not of great value unless there is film in the picture somewhere. The normal test for maximum black is done (typically) in order to find the film base plus fog factor in a sheet of developed film. The characteristics of the paper and developer are dealing with the film, not just the paper.

    Try using the edge of a piece of developed film as your contrast gauge. When this strip shows maximum black, you are in the ballpark and ready to try a test print. Print the film based on this exposure, then look at your highlights and see if they fall into place, are too dark or too light. This will tell you about your development for zone VIII values.

  6. #6

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    Ann it looks as though I followed your directions. However I don't know what a step wedge is. My enlarger is a C760 B&W diffusion model. I tried the blank negative this is the one that gave me the 8 second black at f11. I didn't make any prints because I didn't see the point of making solid black prints. I just figured I need to get past this point first. I suppose I could try an exposed negative tonight.

  7. #7
    Ole
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    8 seconds at f:11 seems very reasonable. With a blank negative you got everything black, which is also about as it should be. That means that every part of the negative which isn't entirely clear, will be lighter than black. And that's how prints are made...

    Try with a negative.
    -- Ole Tjugen, Luddite Elitist
    Norway

  8. #8

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    I've read both of your threads, and I'm still not sure what you're trying to accomplish. Is it:

    1) Finding minimum time for maximum black
    2) Finding the correct exposure for a particular negative
    3) Something else?

  9. #9
    ann
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    A step wedge is a series of exposures made a specific intervals of time. take a piece of enlarging paper and cover all but a 1/4 inch and make an exposure i.e. f8, 3 secs.
    move the cardboard and make another exposure, continue to do this until you have exposed the entire piece of paper. process . what you will have is a step wedge moving from very little gray to black.

    There are various methods to learn how to print and I do not want to get into a flaming war over which one, one should use. The question is how to find minimun time for max black and this will do the trick.
    Find the point at which you can no longer see a line between shades and that is the minimum time for maxium black.

  10. #10
    ann
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    Sorry, i just re-read your orginal message. It is not unusal for diffusion heads to need more exposure.
    Making a print with the min. time for max will not make a print all black. It is only the starting time for the print not the finishing time.

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