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Thread: Stouffer's 4x5 step wedge for exposing negative?

  1. #21
    Claes Uhnér
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    Re: Stouffer's 4x5 step wedge for exposing negative?

    Yes, in Beyond the zone system Davies (1999:71) recommends using 4 EV for testing ISO 100 films with an exposure time of 0,4 seconds.

    In my experience, this works quite well.

  2. #22
    jvuokko's Avatar
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    Re: Stouffer's 4x5 step wedge for exposing negative?

    Quote Originally Posted by uhner View Post
    Yes, in Beyond the zone system Davies (1999:71) recommends using 4 EV for testing ISO 100 films with an exposure time of 0,4 seconds.

    In my experience, this works quite well.
    Now I am really wondering why I got EV 4 level with f/11 only by lowering the enlarger head quite low (it really covers a way less than 8"x10" area)?

    For ISO 400 grade film that would be 0,4s with f/22 - but I just can't get there.
    Part of problem is surely the huge lamp delay, which I estimated to around 250ms.

    After first initial test, it was obvious that I had to change time from 0,4s to 0,6s to compensate delay and as the test strip was so thin, I had to also open aperture by one step to f/16.

    Ofcourse Davis also mentions in his book that 0,4s (2/5s) is a start point for proper time and if it won't give a good exposure then enlarger head must be raised or lowered. But in my case, there's no much chance for lowering enlarger head. So I have either use larger aperture (which is not good, because len's maximum aperture is only f/5.6 and I need to test slow films also, not just ISO 100 and ISO 400).


    To put all this together, I can get desired EV4 for ISO 100 only by using f/8 and thus I cannot test orthochromatic films. With 80A I should use something like f/4 for ISO 100 and my lens is not capable for that. Not saying that orthochromatic films tend to be at ISO 25 range...
    Jukka Vuokko
    Flickr

  3. #23
    Cooke, Heliar, Petzval...yeah
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    Re: Stouffer's 4x5 step wedge for exposing negative?

    I suggest to put your enlarger as high as possible to prevent light fall-off. it could give you false readings on the edges.
    Peter Hruby
    www.peterhruby.ca

  4. #24

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    Re: Stouffer's 4x5 step wedge for exposing negative?

    Quote Originally Posted by ic-racer View Post

    Inexpensive sensitometers are not hard to find,
    If that is the case I wish you would find me one.

    Don Bryant

  5. #25

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    Re: Stouffer's 4x5 step wedge for exposing negative?

    Me too!

  6. #26

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    Re: Stouffer's 4x5 step wedge for exposing negative?

    Quote Originally Posted by nolindan View Post
    Thinking about the light color ... it shouldn't make any difference in step tablet testing.

    All the grains in the film have the same spectral sensitivity - the contrast of the film will not (or should not) change with the color of light.
    That's not right. The spectral sensitivity of an emulsion does vary with wavelength.

    And while we are at it, the contrast of a film does increase as the wavlength increases, so red light gives more contrast than blue light.

  7. #27
    jvuokko's Avatar
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    Re: Stouffer's 4x5 step wedge for exposing negative?

    Story continues.
    Shooting against window with a camera using 'sandwitch' method on film casette would be nice but what I have tested, the light level is just too dim. Could get decent exposure times and apertures for iso 100 and slower films.
    Even tried to put step wedge directly against the window and photograph it because the acrylic plate needs couple of stops more light.
    No success, the light is too low.

    Perhaps during summer it would be different.


    So going back to the BTZS-stylish enlarger exposure. I grabbed my old condenser enlarger from the basement and to my big surprise, it's light is even weaker than my current diffuser enlarger's! Got ev 2 on f/11 @ISO100 (measured from glossy white surface).


    It really seems that my only option is to use sandwith technique like salihonba's example, but using some studio flash lights instead of daylight.

    Drawback: Cannot do tests for 120 materials, only 4x5.
    Jukka Vuokko
    Flickr

  8. #28

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    Re: Stouffer's 4x5 step wedge for exposing negative?

    Quote Originally Posted by jvuokko View Post
    ...
    So going back to the BTZS-stylish enlarger exposure. I grabbed my old condenser enlarger from the basement and to my big surprise, it's light is even weaker than my current diffuser enlarger's! Got ev 2 on f/11 @ISO100 (measured from glossy white surface)...
    Why not open the lens?

    EV2 with ASA400 film should be about right by the way. If you are using some of the ASA25-50 film you will of course need a corresponding increase in light.

    What sort of enlarger has such a dim light?

  9. #29

    Re: Stouffer's 4x5 step wedge for exposing negative?

    Quote Originally Posted by jvuokko View Post

    Drawback: Cannot do tests for 120 materials, only 4x5.
    Why not?






    but I think Finland's Autumn got too weak the sunlight.

  10. #30

    Re: Stouffer's 4x5 step wedge for exposing negative?

    [IMG][/IMG]

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