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  1. #1
    shutterboy's Avatar
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    Film tonal/dynamic range

    First of all, I am trying to relate my digital shooting knowledge to understand film behaviour. So my question might sound a bit strange. I shoot with a Canon 1Ds Mark III and use a Sekonic L-758DR light meter. Sekonic has a feature of building a profile for the camera which it is measuring for looking at shots of a Macbeth (like) colour chart at different exposures (-3,-2,....,+2,+3) and figuring out the point at which details are lost. Once such profile is created, on subsequent measurements it indicates if the total "range" is outside the capabilities of the camera.

    Now for film, I know that it captures much more dynamic range than a digital sensor, but is there a way to figure out how much of wiggle room I have? I guess, I am probably asking, how can I profile a film (say Portra 400) with a L-758DR. I did find a similar question at http://www.largeformatphotography.in...58-light-meter but I did not quite understand the answer.

    Could someone please explain this to me?

    Thanks
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  2. #2

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    Without a step wedge all you can do is shoot the same sceane with static lighting over a large number of stops/shutter speeds.

    Having metered shadows and highlights first.

    Clear film (or fog) to just detectable silver is zone 1.

    The highlight the film just captures is more subjective but you should be able to derive an approximate zone for highlights.

    Trix and HP5+ both high dynamic range PanF less so. Note I still use PanF.

    The dynamic range is also dependent on the developer to a smaller degree as is the base fog level.

  3. #3

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    May I enquire what you think you will gain from your exercise and why do you think it is necessary for your use of film?

  4. #4
    Bill Burk's Avatar
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    I started with a simple premise...

    The Zone System, Normal.

    Zones I through IX encompass 8 stops of range.

    So I set my clipping points at those marks instead of the stock 7 2/3 stops.

    I made a sticker that helps visualize which clipping points correspond to which Zones, when in Shutter Speed priority mode.

    http://beefalobill.com/images/zone.pdf

  5. #5
    Bill Burk's Avatar
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    So to clarify, 8 stops is a reasonable base for clipping points with black and white negative film - based on the "fact" that there is so much available information about how to calibrate black and white film to 8 stops... if you understand Zone System calibration techniques. So many people are familiar with how to calibrate for Zone System that you can get a lot of help. It's well understood and easy to get your head around.

    Color negative, like Kodak Portra 400 would require a different set of clipping points. I "think" that 7 2/3 stop is a good starting point. Negative film, in general, does not clip highlights - that's where you have your latitude. So I think the default is suited for that. But if I were shooting color slide film, I would seriously consider calibrating because slide film doesn't have as much latitude, and you really want to get exposure correct for slides.

  6. #6
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    The technical problem with getting a profile directly into your fancy meter is that to profile a film using Sekonic's system you have to use a scanner, so in essence you are profiling the scanning system's sensor as much as the film. This also seems to be about nailing the "perfect" exposure in camera.

    If that's your normal process it should work fine for you. When/if you change scanners though you'll need to recalibrate.

    I'll assume though that your target is a print from an enlarger in a darkroom.

    First thing to understand about metering for negative film is that finding the perfect answer is fully dependent on your choices in shooting style, subject matter, tools, and artistic preferences for the print.

    For example, Bill's preferences and mine are different. I don't think Bill's f64 membership has been revoked (at least not yet, but I've seen hints that he's worried ) and by holding that membership it means Bill still cares about detail in the shadows and highlights. On the other hand I have more of a pictorial, even soft focus sensibility, I'm generally only looking for hints of detail in the highs and lows to support the main subject in the middle.

    For Bill metering the whole composition, the whole range he wants to print, is important because it's probably all going to be sharp.

    For me metering the background is typically meaningless because the background is going to be blurred and my blurring turns what Bill get as sharp deep blacks and sharp brilliant whites into a bunch of messy shades-of-gray regardless of how either of us meters.

    The practical difference is that I can be less fussy about nailing perfect camera exposure than Bill, even with the same film, because the range of detail I want to print from the scene is typically narrower.

    Second thing to understand about negative film, shadow detail is the hard limit.

    I like to think of the low exposure limit as the place I can get my "first excellent print". For me with Portra 400 this about EI 800 but I prefer shooting it at EI 400 to build in a safety factor and reduce grain. Here you simply need to experiment to see how low you can go without screwing up the print.

    Third thing to understand about negative films is that a)only the important detail range matters, b)the high limit is typically really high, and c)that adjusting the enlarger exposure allows you to adjust for variances in camera exposure. (I put these all as one point because they are interdependent and as a group they are why film exposure is so flexible.)

    http://www.kodak.com/global/en/profe...4050/e4050.pdf on page 5 the straight line portion of the curve shows roughly a 10 f-stop range (3-stops per log unit) and no hint of shouldering.

    What that means for me is that within my subject matter preferences, which typically has a 5-6 stop important detail range, if I shoot Portra 400 at 800 I will have 4-5 stops of extra highlight detail on the negative that I probably won't use in the print. (IME it's actually even more than that and if I do decide I want that detail I just need to burn it in.)

    That extra "dynamic range", to use your lingo, means that I could shoot the same scene/shot at EI 800, EI 400 or EI 25 or anywhere in between, and then by just adjusting enlarger exposure, I could make essentially equal print copies from any of any of those negatives and you would be hard pressed to tell which print came from which negative. This demonstrates film's "latitude".

    Film's latitude is why disposable cameras, Holgas, and many other simple cameras can produce good results. I love the simplicity of throwing Portra 800 in my Holga and shooting all day without any worry about setting exposure or if I got it. Just set the focus distance, shoot, advance the film, and I know I got it.

    There are lots of creative ways to use this. When using my RB67 I can surely get a perfect exposure for Portra 400 at EI 400 but I'll still use the EI float, the latitude. Floating the EI gives me more creative control over DOF and motion blur. For example I'm happy as a clam shooting Portra 400 at EI 25, or even EI 12, if I want to use an f4 aperture when it's sunny 16 out or I want to blur a waterfall.
    Last edited by markbarendt; Yesterday at 12:29 PM. Click to view previous post history.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  7. #7
    Bill Burk's Avatar
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    markbarendt,

    It was fun to read your post because I think you represented my approach and needs accurately...

    While latitude allows overexposure to a greater extent and underexposure to a lesser extent... That's variation in the exposure placement. The subject range of brightness (in areas that are important for the shot) gives best color when you hold it to a certain limited range.

    I've been reading some interesting old booklets since my sister came to visit. The Camera, Pocket Photo Guide - interesting because it covers everything there was to know about photography in 1942... in 128 tiny pages...

    It recommends for Kodacolor... "the maximum exposure variation which will produce properly colored results should not exceed two diaphragm stops."

    Lots of early color photography was supplemented with flash or great pains were taken to adjust lighting to keep the brightness range in check. And some (many?) people still do that.

    I think my simple approach to setting clipping points in the Sekonic meter for black and white would work for color too. I don't think you have to go wild with calibration and scanning to get effective points.

    A densitometer could be used to read the negatives that you shoot in a carefully conducted test. Example, from the spec sheet there is a density target for the bright forehead of a person... You could take close-up portraits of a subject, adjust the exposure in third-stops if your camera allows (or just do the best you can in full stops)... Then put the negative on a densitometer and read the densities... That number of third-stops from the metered point that gave you the right density on the negative (for your subject's forehead) can become the "inner-upper" clipping point. You would do a similar experiment for shadows. Since it was derived by an experiment, I believe the result would be as valid as a shot of the "official Sekonic exposure target".

  8. #8

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    Quote Originally Posted by MartinP View Post
    May I enquire what you think you will gain from your exercise and why do you think it is necessary for your use of film?
    Probably my question is stupid, and certainly badly phrased. Just to confirm that the OP understands that exposed film does not have hard, neat points at which it begins and ends recording printable detail. Film isn't like a straight-line digital sensor, so using a meter with a digital-exposure aid built in isn't so useful surely?

    Pegging exposure to some value for a particular piece of subject-surface is fairly standard, while specifically considering the rest of the tones in the scene might tend towards the Zone idea, but neither are based on values for totally dark black and totally blown white - as used for limits in the digital-exposure aid, in the meter.

  9. #9
    markbarendt's Avatar
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    Quote Originally Posted by Bill Burk View Post
    Lots of early color photography was supplemented with flash or great pains were taken to adjust lighting to keep the brightness range in check. And some (many?) people still do that.

    I think my simple approach to setting clipping points in the Sekonic meter for black and white would work for color too. I don't think you have to go wild with calibration and scanning to get effective points.
    Glad you enjoyed.

    Flash is an incredibly useful tool still and yet as is adjusting lighting. Helps avoid bunches of burn and dodge.
    Mark Barendt, Ignacio, CO

    "We do not see things the way they are. We see things the way we are." Anaïs Nin

  10. #10

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    Quote Originally Posted by shutterboy View Post
    First of all, I am trying to relate my digital shooting knowledge to understand film behaviour. So my question might sound a bit strange. I shoot with a Canon 1Ds Mark III and use a Sekonic L-758DR light meter. Sekonic has a feature of building a profile for the camera which it is measuring for looking at shots of a Macbeth (like) colour chart at different exposures (-3,-2,....,+2,+3) and figuring out the point at which details are lost. Once such profile is created, on subsequent measurements it indicates if the total "range" is outside the capabilities of the camera.

    Now for film, I know that it captures much more dynamic range than a digital sensor, but is there a way to figure out how much of wiggle room I have? I guess, I am probably asking, how can I profile a film (say Portra 400) with a L-758DR. I did find a similar question at http://www.largeformatphotography.in...58-light-meter but I did not quite understand the answer.

    Could someone please explain this to me?

    Thanks
    I have the same meter and the whole exercise is pointless, I call it "nerdgasim" and it's very prevalent on digital forums. The time to do it can be much better invested. I didn't even bother doing it with my DSLR.

    Learn the zone system and use it accordingly. -3 is black, +3 is white. That's the simplest way to look at it. Don't go below -3 or you will not have detail, everything that will overexpose will be ok. For that reason I shoot Portra 400 and Pro400H at EI200.

    I shoot meter the same with slide film, except that I know that if it's +3, it will be white and above that there will be no detail.

    Stick to the KISS principle and have fun instead of spending lots of time doing 1000s of photos which will be also affected by your scanners built in auto adjustments etc...

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