Test Strip Results.

Discussion in 'Enlarging' started by Magic Rat, May 25, 2004.

  1. Magic Rat

    Magic Rat Member

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    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. ann

    ann Subscriber

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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. Ole

    Ole Moderator Staff Member Moderator

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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.
     
  4. sparx

    sparx Member

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    Are you perhaps confusing test strips with pre-flashing paper?
     
  5. noseoil

    noseoil Member

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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. Magic Rat

    Magic Rat Member

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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. Ole

    Ole Moderator Staff Member Moderator

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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.
     
  8. moose10101

    moose10101 Member

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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. ann

    ann Subscriber

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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. ann

    ann Subscriber

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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.
     
  11. Magic Rat

    Magic Rat Member

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    Moose, I'm just going by a book I have that recommends doing a maximum black test. I just took another look at the test strips in daylight and the one I got to work shows a slight difference between 8 and 10 sec. So I am to assume that 10 sec. is the starting exposure for this paper at f11? Is it the maximum time? I just thought that the paper turning black at 8-10 seconds was really short. I understand that this was supposed to give me a starting point for exposure. I guess I was thinking once it reaches black it's, er, "done" :smile: So, I take it this is necessary for every negative I want to print? Thanks ann for responding cause it helped clear my thinking. Ole, thanks for the tip now I have another way to test. Last night was my first time in a darkroom and I'll try to make this as painless as possible for everyone. I no longer fear the dark.
    The Rat
     
  12. noseoil

    noseoil Member

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    Next step

    Dear Mr. Rat,

    It seems you have the correct time for a minimum exposure for maximum black. I can certainly sympathize with you and your efforts. I was in the same boat just a year and a half ago. I work in a vacuum here, with one friend to bounce ideas off of about darkroom work.

    The next step you have is to use this information to find out the correct printing time for a negative. The procedure you use will be the same, but you will be using a sheet or piece of exposed and developed film to find out the same information about the film's unexposed edge. Since the film acts as a sort of filter that lets less light through to the paper, you will be printing to find maximum black with respect to the film and its development. The time you have will be a bit longer, because film is never 100% clear. It stops a little light, but there will be the same result as you reach your goal. I use a sheet of film that is not exposed (but is normally developed) to find out the exposure for "film base plus fog." This is just a baseline for exposures, as each exposure will vary a tad around this value. More film exposure means a longer print time, less exposure can mean less print time.

    Please know that everyone here is with you and wants your tests to be a success. Keep plugging away at it and it will begin to make sense. Sometimes we forget how much we have learned, and how difficult it is to pass this on with words.
     
  13. Magic Rat

    Magic Rat Member

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    Thanks, Nose for the support and tips. I miss hiking in Sabino Canyon and out to Seven Falls.
     
  14. John_Brewer

    John_Brewer Member

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    Hello Ratty, I think if you're fairly new to working in the darkroom IMHO you should put the book down you're reading a way for a while. You should be having fun in the darkroom now, not worrying about DMAX/DMIN etc. I am not knocking the book you have, it will be a godsend in the future. :smile:

    One way I work is with an average neg in the enlarger, grade 2 filter and i'm only interested in getting the correct detail in the highlights. A test strip or two later I have, say, detail on a white washed wall. I have a rough exposure time now, and can concentrate with the contrast by varying the filteration. The filteration test strips will allow you to control the contrast without worrying too much about highlight detail and exposure time. Then you're close to a good print, just a matter of tweaking!

    Keep your not so good prints ( too flat/contrasty/over/under/exposed) in a scrapbook for reference with notes you've made - it will save you a fortune in film and paper!
     
  15. Magic Rat

    Magic Rat Member

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    Thanks John. Okay everyone, my first print is uploaded in the standard gallery. Thanks for the help.