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Thread: Slide film metering

  1. #1

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    Slide film metering

    Iíve stocked up a ton of slide film both expired and current and have been trying to learn how to meter it correctly. Using my Sekonic spot meter Iíve been spot metering the darkest area that I want to retain detail as well as the brightest and averaging. Iíve read that I want to make sure to stay within +2/-2 on both the highlights and shadows. (roughly)

    Letís say my highlights come in at +2.3EV and the shadows at -2.3EV. In this situation, I would need to both brighten up the shadows and darken the highlights, correct? Would this method be correct:? Lighten up my shadows .3EV by exposure compensation and then darken the highlights with my ND grad .3EV + the .3EV from the shadow exposure compensation? Or do I leave the shadows where they are and just bring down the highlights?

  2. #2

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    Re: Slide film metering

    +2.3 Ev may be risky...

    First is that mechanical shutters are not exact with factory tolerance of +/-30%. This means that 1/30 can be 1/20 or 1/40 and this is a full stop, this is in a brand new shutter.

    So to shot LF slides first is checking shutters with a shutter tester.

    For metering, let me suggest a "calibration test", then:

    1) Load a "modern" SLR (Nikon F80, F5) with a roll of the slide you are to use. Select spot meter.

    2) Find a contrasty scene, select a base exposure. Use SLR spot meter (and the Sekonik) and anotate what over/under exposure you have in each area of your scene: Clouds sky, water, rocks, forest, skin. I do that with smartphone or tablet, I take a shot of the scene wioth it and I edit it with and draw a symbols (points slashes) on the image to indicate what over/under exposure had every area.

    3) Then make a bracketing (anotate what shot number is what frame of the bracketing), say from -3 to +3 stops, this is 7 shots for each scene. So with a single 35mm roll you may test 5 scenes.

    4) Then knowing the under/over exposure of every area (base + bracketing) you will see how different subjects (sky, water, forest ) look at every level of under/overexposure.

    IMHO It is a (painful) crime to not expose well an slide, slides have to be nailed, so maximum care sholuld be taking. Imagine a burnt 8x10 velvia... painful.

    Of course graded ND, Pol, etc may be needed with velvia to not burn the sky, but you should test on your own to learn what is +2EV or +3EV with Sky or Clouds. Or how your scanner reads shadows...

    Regards

  3. #3

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    Re: Slide film metering

    Another approach for finding a "baseline" quickly would be to take an incident reading. You'd be surprised how often that alone will yield a
    correct" exposure, assuming a "normal" scene". No matter the scene type, it gives a place to start and the exposure can be adjusted up or down accordingly.

  4. #4
    8x10, 5x7, 4x5, et al Leigh's Avatar
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    Re: Slide film metering

    Quote Originally Posted by BrianShaw View Post
    Another approach for finding a "baseline" quickly would be to take an incident reading. You'd be surprised how often that alone will yield a correct" exposure, assuming a "normal" scene".
    Absolutely true.

    That's what the film manufacturers did.
    They had a whole lot more time, equipment, and budget than you do.

    - Leigh
    If you believe you can, or you believe you can't... you're right.

  5. #5

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    Re: Slide film metering

    You can't recover from over-exposure with color reversal material. So the old rule is to expose for the highlights.

    You have a maximum of 5 stops latitude. that's 2-1/2 stops on either side of "Zone 5" or the "middle" density of your exposure range. Anything brighter than 2-1/2 stops over middle will blow out. Anything less than 2-1/2 stops of luminance from middle gray will be underexposed. But underexposure is far lass objectionable with slide film. Visually, underexposed areas may appear acceptable on a light table but you'll never be able to get decent scans/prints from more than 5 stops of the original scene.

    Learning to measure highlights correctly (preferably with a spot meter) and correlating that measurement with an average reflectance reading or with an incident reading is the best way to assure accurate exposure.

    Since you have "a ton of slide film," you should run tests and carefully record your measurements to find your equipment's characteristics.

    Rich

  6. #6
    ic-racer's Avatar
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    Re: Slide film metering

    The speed point is in the light area of the film, just like negative film. That light area, turns out to be the highlight. So meter the highlight to get that in the right place on the curve.
    Click image for larger version. 

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  7. #7

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    Re: Slide film metering

    Quote Originally Posted by Leigh View Post
    Absolutely true.

    That's what the film manufacturers did.
    They had a whole lot more time, equipment, and budget than you do.

    - Leigh
    My view is that (with slides) indirect metering is very consitent in some particular conditions, like flowers in the shadow, but it is not as good under challenging conditions, for example if we have a landscape with sun relatively low we will need to know if clouds and sky are to be overexposed and by what amount, and what graded ND filter we have to add to preserve color and detail in the sky, in those conditions spot metering is important.

  8. #8

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    Re: Slide film metering

    Quote Originally Posted by nbagno View Post
    Iíve stocked up a ton of slide film both expired and current and have been trying to learn how to meter it correctly. Using my Sekonic spot meter Iíve been spot metering the darkest area that I want to retain detail as well as the brightest and averaging. Iíve read that I want to make sure to stay within +2/-2 on both the highlights and shadows. (roughly)

    Letís say my highlights come in at +2.3EV and the shadows at -2.3EV. In this situation, I would need to both brighten up the shadows and darken the highlights, correct? Would this method be correct:? Lighten up my shadows .3EV by exposure compensation and then darken the highlights with my ND grad .3EV + the .3EV from the shadow exposure compensation? Or do I leave the shadows where they are and just bring down the highlights?
    You've got it right if, when you say "darken the highlights with my ND grad .3EV + the .3EV from the shadow exposure compensation", you mean that you will use a ND grad to darken the highlights by .6EV. Your phrasing was slightly ambiguous, at least to me. After you lighten the shadows by .3EV, the highlights, previously at +2.3EV, are now at +2.6EV, so they must be brought down .6EV with the ND grad to fit in the +2/-2 range.

    Of course that is assuming you want to fit everything in the +2/-2 range. Depending what you seek to achieve in the image, you could leave the shadows where they are and just bring down the highlights. That would leave some shadow area blocked, but maybe that would work - depends on the image. The opposite, retaining the shadows and blowing (significant) highlights, usually doesn't work in my opinion.

  9. #9

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    Re: Slide film metering

    Quote Originally Posted by Pere Casals View Post
    +2.3 Ev may be risky...

    First is that mechanical shutters are not exact with factory tolerance of +/-30%. This means that 1/30 can be 1/20 or 1/40 and this is a full stop, this is in a brand new shutter.

    So to shot LF slides first is checking shutters with a shutter tester.

    For metering, let me suggest a "calibration test", then:

    1) Load a "modern" SLR (Nikon F80, F5) with a roll of the slide you are to use. Select spot meter.

    2) Find a contrasty scene, select a base exposure. Use SLR spot meter (and the Sekonik) and anotate what over/under exposure you have in each area of your scene: Clouds sky, water, rocks, forest, skin. I do that with smartphone or tablet, I take a shot of the scene wioth it and I edit it with and draw a symbols (points slashes) on the image to indicate what over/under exposure had every area.

    3) Then make a bracketing (anotate what shot number is what frame of the bracketing), say from -3 to +3 stops, this is 7 shots for each scene. So with a single 35mm roll you may test 5 scenes.

    4) Then knowing the under/over exposure of every area (base + bracketing) you will see how different subjects (sky, water, forest ) look at every level of under/overexposure.

    IMHO It is a (painful) crime to not expose well an slide, slides have to be nailed, so maximum care sholuld be taking. Imagine a burnt 8x10 velvia... painful.

    Of course graded ND, Pol, etc may be needed with velvia to not burn the sky, but you should test on your own to learn what is +2EV or +3EV with Sky or Clouds. Or how your scanner reads shadows...

    Regards
    I have a shutter tester and started testing on my crown graphic. Slow speeds were fine, fast speeds were way off... Thanks for the reply.

  10. #10

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    Re: Slide film metering

    Thanks. I do spot meter but was asking if my method of bumping up the shadows and compensating for that with an equal darkening of the highlights via an ND was a valid method.

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