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  1. #11
    craigclu's Avatar
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    Denis, I printed onto some transparency film on my laser printer. The density didn't get as deep as it appears in the pdf file but I ran it through a densitometer so that you could at least see the relationships between the tones. The vagueries of equipment, etc make the numbers for comparison to standard printed materials not useful but the general relationship between the wedges might be interesting for you. They showed a slight hash pattern at 600 dpi that your professionally done sample likely doesn't display. Anyway, here's a plot in log scale.
    Attached Thumbnails Attached Thumbnails wedge.jpg  
    Craig Schroeder

  2. #12

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    I always found the Kodak thingy better in theory than practice. I have also discovered that as they age, they get quite a bit of B+F, I think it's the plastic they use.

    It seems that except on small prints, there just isn't enought area to get a reliable fix on exposure time. And then, ten second is underexposed and twenty is too much. OK, now we are back to a test strip, 10, 12, 14, 16, 18, seconds.

    Oh well.

  3. #13
    Denis P.'s Avatar
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    Craig, thans for the log scale!

    If you want, I could send you a real one by mail (i.e. by snail-mail, in an envelope), so you can do an exact measurement/plot. You can keep the one I send you - I have three, and can make more without too much hassle

    I'll PM you...

    BTW, I tried "measuring" the densities/values using my EM-10, but it's not really very usable for this purpose (to be used as a densitometer....)

    Denis

  4. #14

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    Quote Originally Posted by Denis P. View Post
    Well, despite all the naysaysers, I went ahead with this project.

    With the help of a friend, I devised a step wedge of a kind - well, more like a pie chart...

    Could come in handy. The way I do test strips is rather slow - this might speed thing us just a litlle bit.

    Denis
    My method takes a long time too.

    But Cool!
    How many did you make?
    I'd like to try one out!

    Ray
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  5. #15

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    Quote Originally Posted by Ray Rogers View Post
    My method takes a long time too.

    But Cool!
    How many did you make?
    I'd like to try one out!

    Ray
    Ooops!
    I should have read the next page!
    Last edited by Ray Rogers; 06-04-2008 at 03:05 AM. Click to view previous post history. Reason: ugh?

  6. #16
    craigclu's Avatar
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    I rec'd the material today and ran a quick density test. I'm attaching a spreadsheet and a shot of the chart with the results. I ran each section twice and got the same reading each time. I found a very slight difference in the pie wedges and the rectangles. The black section around the labels gave a 2.45 result, by the way....

    Denis sent some nice shots that he had done. Good subjects and interesting architecture, too!
    Attached Thumbnails Attached Thumbnails perc_dens.jpg  
    Attached Files
    Craig Schroeder

  7. #17
    richard ide's Avatar
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    Denis,
    I think that there is a difference between what you had made and a projection print scale. Yours, done on graphic arts film, is a halftone representation of a grey scale step wedge. Projection print scales and step wedges are printed on continuous tone film and the steps are varying densities. If you look at the one you had made with a magnifier, the steps are really high density film with varying hole sizes. It may work but I suggest you test it by making a contact print which just gives you maximum black and examine the steps with a magnifier. If you can see dots in the areas, then you are getting an approximation of a grey scale.
    I don't want you to get misleading results. I think that you can make one yourself which although not balanced against a projection print scale as far as exposure times, would give you a very accurate and reproducable result. Photograph a grey card (or a sheet of white paper) at different time/aperature combinations in 1/2 or 1/3 stop steps using any BW film. What you end up with is a whole series of negatives of varying density. Using a light table or other source of backlight, choose negatives which come closest in appearance to your graphic arts scale. Look at them from normal reading distance. Then take portions of these and tape to a piece of clear film. You now have a very accurate duplicate of a print scale. If your friend can; ask him to measure densities for you and make your own step wedges.
    In my business which involved photographing two dimensional originals of all kinds, a grey scale was always used in the image. If an employee made a negative, this scale allowed me to see in a second if it was of the high quality desired, or exposure/processing was the best possible.
    Richard

    Why are there no speaker jacks on a stereo camera?

  8. #18
    Denis P.'s Avatar
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    Quote Originally Posted by richard ide View Post
    ...
    It may work but I suggest you test it by making a contact print which just gives you maximum black and examine the steps with a magnifier. If you can see dots in the areas, then you are getting an approximation of a grey scale.
    Yes, that's what it looks like.
    However, the results are "close enough for the Government work", or, better said, those could be used for the intended purpose.

    Quote Originally Posted by richard ide View Post
    ...
    Then take portions of these and tape to a piece of clear film. You now have a very accurate duplicate of a print scale. If your friend can; ask him to measure densities for you and make your own step wedges.
    As mentioned above, I just need something that's "close enough" to be used as an aid in the darkroom. I.e. instead of making 2-3 test strips, I'll make just one, which would (hopefully) give me a starting point.

    But, I think I'm getting better in my darkroom work - I just have to force myself to record everything. Once I consult my notes, everything usually goes a lot faster
    Yesterday I even managed to make a contact sheet (almost) on the first try - even though it was done on a paper I don't use much (very slow one).
    I eyeballed it, and decided to try 30 seconds with a small test strip. It turned out it needed to be just a bit shorter - so I made the full contact sheet with 25 second exposure... just about right...

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