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Thread: Film speed testing

  1. #1

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    Film speed testing

    Okay, I'm trying to do a film speed testing, but the two sources I have, do it in increments/decreases of 1/2 or 1/3 stops. Now, I'm a newbie. 1/2 and 1/3 stops may not be complicated to you more experienced fellows, but they are to me, a beginner soul. Can someone please give me the easy version of the film speed test? In whole stops? None of this half or third business? These are my requirements:

    I'm testing my large format Sinar F2 (obviously sheet film)
    I have access to a densitometer
    I have a gray card (I know there are ways of doing this test without one, but I want to do it with a card)

    I think that's it. I can't think of anything else. Can someone give me the easy version of the film speed test? Thanks.
    --Mario

  2. #2
    SpeedGraphicMan's Avatar
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    Re: Film speed testing

    "I would like to see Paris before I die... Philadelphia will do..."

  3. #3
    ic-racer's Avatar
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    Re: Film speed testing

    Guess at an exposure index, set that on the meter, expose the card putting it at zone 1, process the film and check that it is 0.1 log d. Repeat as needed to find the proper exposure index.

  4. #4
    retrogrouchy
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    Re: Film speed testing

    I would recommend acquiring a copy of Beyond The Zone System by Davis. It lays it all out fairly neatly, though you will need to buy a (not very expensive) step wedge.

  5. #5

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    Re: Film speed testing

    Get a ride to Pacifica and bring about 10 sheets of film...

    I need a guinea pig to practice the material for my class... "Calling your shots, the timeless appeal of popular sensitometry". So you'll be helping me and in the end you'll either be totally confused, or you'll know every way to test film...

  6. #6

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    Re: Film speed testing

    Re: Film speed testing
    Give this a read through...

    http://www.earthscenics.com/manuals/zoneman_8_11_05.pdf

    I'm just getting started in LF myself, and am about ready to start doing some testing on my own, hopefully this weekend. I have several lenses and cameras.

    I read the above and I wonder if it means that you would have to do the calibration for each camera/lens combination you have??? A different ISO for this camera with that lens...etc?
    Or does the camera have very much to do with it? All my lenses are attached to shutters, so would I have to do this test for ISO determination just for each lens?

    That is very complicated, how does everyone else handle having more than 1 lens and used on more than 1 camera? I have a speed chart for each lens I have and I keep it with me, I trust the aperture settings.

    Thanks, Bill

  7. #7

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    Re: Film speed testing

    Quote Originally Posted by Bill, 70's military B&W View Post
    Re: Film speed testing
    Give this a read through...

    http://www.earthscenics.com/manuals/zoneman_8_11_05.pdf

    I'm just getting started in LF myself, and am about ready to start doing some testing on my own, hopefully this weekend. I have several lenses and cameras.

    I read the above and I wonder if it means that you would have to do the calibration for each camera/lens combination you have??? A different ISO for this camera with that lens...etc?
    Or does the camera have very much to do with it? All my lenses are attached to shutters, so would I have to do this test for ISO determination just for each lens?

    That is very complicated, how does everyone else handle having more than 1 lens and used on more than 1 camera? I have a speed chart for each lens I have and I keep it with me, I trust the aperture settings.

    Thanks, Bill
    I'm afraid your worst fears are about to materialize. My understanding is that the combination camera, lens, film is what determines the appropriate film speed. So, depending on how many lenses you use on a given camera, and hoping--for your sake--that you only use one kind of film, that's how many combinations you have of film speed. So, one camera, three lenses, and assuming just one kind of film, will have up to three different results.

    Luckily for me, for my 4x5, I only have one lens and one kind of film I use. So my testing becomes very easy.
    --Mario

  8. #8

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    Re: Film speed testing

    No it's really not all that bad!

    I recommend undertaking this as a journey to understand film exposure and processing - rather than a precision endeavor.

    So pick your "normal" setup and follow the Zone System tests that make the most sense to you. It's learning to give enough exposure and developing to suit your needs that's important.

    Time and temperature and the massive dev chart and everyone's advice work too because you really have a lot of leeway.

    But you get a lot of satisfaction knowing you picked the Exposure Index and development time because they are right for you. You will feel proud of yourself that for once you didn't just follow somebody else's charts without understanding how the charts were created.

  9. #9

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    Re: Film speed testing

    I appreciate everyones input, and I WILL take the advice.

    But thinking of it logically...
    The way I see it, the film is a constant, regardless of what camera or lens...
    Shutter speed is something that you can test to see what you are actually getting...so that becomes a pretty reliable factor.

    The unknown, untested, take on faith factor is the aperture.

    Logic would dictate that it is the aperture that has variables in it. f/8 on this lens lets in more light than f/8 on that lens, therefore I have to change the ISO to compensate.
    I do not see any other way to compensate except by varying the ISO, but aperture is where I see the problem originating.

    I'm a newbie just looking at this and trying to understand it. I'm sure it's been studied/tested, is there any other explanation?

  10. #10

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    Re: Film speed testing

    Quote Originally Posted by Bill, 70's military B&W View Post
    Re: Film speed testing
    Give this a read through...

    http://www.earthscenics.com/manuals/zoneman_8_11_05.pdf

    I'm just getting started in LF myself, and am about ready to start doing some testing on my own, hopefully this weekend. I have several lenses and cameras.

    I read the above and I wonder if it means that you would have to do the calibration for each camera/lens combination you have??? A different ISO for this camera with that lens...etc?
    Or does the camera have very much to do with it? All my lenses are attached to shutters, so would I have to do this test for ISO determination just for each lens?

    That is very complicated, how does everyone else handle having more than 1 lens and used on more than 1 camera? I have a speed chart for each lens I have and I keep it with me, I trust the aperture settings.

    Thanks, Bill
    With a shutter that's in the lens (as opposed to being in the camera) as is the case with most lenses used for LF photography the camera has nothing to do with it, only the apertures and shutter speeds of your lenses are relevant in testing to determine your film speed.

    You wouldn't normally use different film speeds with different lenses. Many people do test the shutter speeds of all their lenses whether they've made made film speed tests or not just because it's a good idea to know whether there's a significant difference between one or more speeds marked on the shutter and the actual speeds. And if that's done and differences are found they'd adjust the exposures to take that difference into account when they used that shutter speed to make a photograph. While the exposure change could be made by adjusting the film speed it's much simpler to do so by adjusting the shutter speed or aperture rather than trying to figure out what new film speed would give you the desired change in exposure.

    But again, testing shutter speeds is something that's often done completely apart from any film speed testing you've done. The film speed you determine after testing for film speed normally remains constant.
    Brian Ellis
    Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
    a mile away and you'll have their shoes.

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