The M.C.M Wedge Manufactured by Ilford Limited

Discussion in 'Classic Manual Cameras' started by John Seaman, Feb 5, 2021.

  1. The M.C.M Wedge came with a box of photographic bits and pieces from the auction site. It consists of graduated grey strips of cellulose graded from 1 (clear ) to 9 (black) sandwiched between two 4 inch glass plates.

    It has a satin lined fitted case labelled M.C.M Wedge Manufactured by Ilford Limited. I wondered what it was for and was surprised to find a Google hit to the excellent Photomemorabilia website, with a PDF of Ilford News for Photographic Societies, Series 1 Number 5 of March 1939.

    LINK --- https://www.photomemorabilia.co.uk/Ilford/Chronology/Ilford_News_Sr1No5_Mar39.pdf

    It says "The M.C.M. Step Wedge has been designed by the editor of the Miniature Camera Magazine in collaboration with our Research Department as an aid to serious photographers who wish to classify papers by an accurate method of testing."

    But, tantalisingly, "It is impossible to give full details here owing to space limitations, but readers will find a full description in the Miniature Camera Magazine for March." So - any ideas?

    Wedgek.jpg Wedge2.jpg
     
    Last edited: Feb 5, 2021
    johnfantastic likes this.
  2. Sandy Vongries

    Sandy Vongries Administrator Staff Member

    Last edited: Feb 5, 2021
  3. That's interesting Sandy. The article talks about "to classify papers by an accurate method of testing". The Wedge has nine gradations, whereas the Print Scale has ten. It's tempting to compare these with the eleven zones of the Zone System, but I don't suppose there's a direct connection.
     
  4. I assume it's the forerunner of the common 21 step tablet and would be used in a similar fashion. Hopefully they supplied the density of the steps.
     
  5. Kodak made a similar printing 'wedge'. Except the kodak one was circular with segmented steps.

    The Kodak one I have was designed to be laid on top of a small square of printing paper under the enlarger (with negative fitted and focussed up). It was then exposed for 60 seconds, and the time read off from the best exposed segment.

    Its secondary use was for calibrating the contrast grade of papers. This was done by seeing how many steps were visible, from black to pure white.

    I used it precisely once, to assess its usefulness.... it had none!

    Your M.C.M wedge appears to be in one-stop steps, but it's not possible to assess the density accurately from what's shown.
     
    johnfantastic likes this.
  6. Yes, they are 1 stop apart, as near as I can tell. I put the wedge on a light box and measured the light values of the sectors using my Sekonic View Spot Meter L438, with the spot set at 4 degrees. The LV readings of the sectors were (sectors 8 and 9 weren't really readable):

    1 - 12.6, 2 - 11.7, 3 - 10.8, 4 - 9.8, 5 - 8.5, 6 - 7.6, 7 - 6.7
     
  7. That's about as good as you'll get with 1 stop exposure steps on a bit of film.

    It's near impossible to develop exactly to a gamma of 1, and across several stops of exposure.

    I found the indicated exposures with my Kodak segments to be quite a way off. I could have calibrated it, but I already had a neat little Philips enlarging meter sitting on the bench. So it went back into its little polythene sleeve and paper envelope, and disappeared into the 'odds & sods' drawer.
     
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  8. Just as a sort of public service, for those inquiring minds, here is a little more data on the
    Kodak Projection Print Scale, Publication R-26
    Kodak projection print scale R-26s.jpg

    Here is what the Kodak Black & White Darkroom DATAGUIDE (R-20) has to say about it

    There are a few still for sale, some looking like new, old stock, on eBay = asking prices $10-20 US
     
    Last edited: Feb 9, 2021
  9. I'm hardly surprised that there are plenty of unused ones still around.

    But 20 bucks?!
    As a gift it would still be overpriced!:p
     
  10. Kodak quasi-recognized that fact by providing the following information

    Making a Test Strip-You can determine
    exposure in a number of ways. An experienced
    technician can estimate the
    exposure time closely by viewino the
    density of the enlarged im.age. A photometer
    measures the brightness of portions of the
    image and calculates the exposure from the
    readings. Many people rely on a combination
    of experience and making a test-strip
    exposure series.

    To make a test-strip exposure series:
    1. Place your negative in the enlarger and size
    and focus the image. Turn off the enlarger
    light.
    2. Cut a sheet of your printing paper into
    lengthwise strips at least 2 inches wide.
    3. Place a test strip emulsion side up on the ยท
    easel where it will be exposed to an area of
    the image that represents a typical range of
    negative densities. Place a piece of cardboard
    over about four fifths of the strip, and
    make a series of exposures at selected
    intervals, uncovering another fifth of the
    paper after each exposure, until the paper is
    completely uncovered during the last
    exposure. Experience helps in determining
    the exposure intervals to use on the strips.
    Exposures will vary with negative image
    density at the degree of enlargement you
    are using and with the speed of the paper.
    A bright image might indicate intervals of
    2 seconds and a dark image intervals of
    10 seconds. At 2-second intervals, you
    would have portions of the image exposed
    for 2, 4, 6, 8, and 10 seconds.
    4. Develop the test strip normally; fix it for at
    least 2 minutes. (See page 54.)
    5. Evaluate the strip in white light. One of the
    steps on the test strip should be at or close
    to the correct exposure. If one step is too
    light and the next is too dark, an exposure
    in between should be easy to select. If all
    the steps are too dark, use a smaller lens
    aperture or shorter exposure interval, and
    make another test strip. If they are all too
    light, use a larger lens opening or exposure
    interval.

    When you establish the best
    exposure on a test strip, you are ready to
    make a full-size test print.
    Kodak B&W DarkroomGuide p50-1.​
    The benefit of the Kodak Projection Print scale was that it read out with the needed expoiure
     
    James Bryant likes this.
  11. Give or take a number of seconds!
     
  12. Well, an indirect connection. It is 10 zones as that is, more or less, what film can do, and also,
    again more or less (probably less) what paper can do.

    The Kodak Projection Print Scale that I have (present from my grandfather pretty early
    after I started) goes from 2 to 48, so about 4.5 stops.

    Not so obvious if a continuous or stepped scale is best.
     
  13. hmmmmmm very informative discussion although I can just read, I know very little about darkroom processes. :)
     

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