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Thread: Average Spot Metering Question

  1. #21

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    Re: Average Spot Metering Question

    The problem with basing your exposure on an average is that if the contrast range in the scene exceeds "normal," then the middle value you end up basing your exposure on is pretty high. This results in underexposing the low values and the corresponding loss of detail. In other words, you are no longer "exposing for the shadows," which is a better method than averaging.
    Right on queue Doremus, you were correct.

    I did a test exposure yesterday using the average of 3 values as I have never tried this before.

    I metered the deepest part of the trees, the middle value on the bridge and the brightest part of the sky and then hit the AV button and used that for the exposure.
    You were correct, the image is under-exposed and the shadow areas have indeed lost detail.

    Click image for larger version. 

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    Apologies for allowing the cable release to enter the frame to busy trying to mentally see what the average would give me

  2. #22

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    Re: Average Spot Metering Question

    Quote Originally Posted by Alan9940 View Post
    I can tell you for fact that the Pentax Digital Spot meter that I've used for many a year reads out EV values based on the luminance of the object the spot is on...period. I'm pretty sure the Sekonic works the same way, but now that you've brought it up I'm definitely going to test it.
    Yes - from recollection, the Pentax uses EV without shifting around with ISO changes. I think the ones that shift the EV numbers around call it 'LV' or something like that - not that it makes a big difference in actuality, other than confusing everyone!

  3. #23
    Land-Scapegrace Heroique's Avatar
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    Re: Average Spot Metering Question

    Quote Originally Posted by Doremus Scudder View Post
    To ensure you have the shadow detail you desire you have to base your exposure on an important shadow value, placing it so it has the amount of detail/separation you want. This determines exposure. Then you check the highlights to see where they will end up and make adjustments to development, choice of paper grade, filtration, etc. at that point.
    I thought a concrete example regarding "adjustments to development" might also be helpful…

    This is a chilly shot near Mount Rainier where I aimed for detail on two ends of a very wide zone range, so I chose compensation development to rescue the highlights.

    Here, the darkest tree-boughs were zone 3. The sunny dimpled snow was above zone 9.

    I used dilute HC-110 – that is, 1+123 direct from concentrate (not stock), and tray-developed for 19 minutes in 68° F, w/ a little bit of agitation every few minutes. All the snow has texture in straight prints from my Omega D2-v.

    Click image for larger version. 

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    Tachi 4x5
    Schneider 150/9 g-claron
    Ilford FP4+ (in dilute HC-110) in trays
    Epson 4990/Epson Scan

  4. #24

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    Re: Average Spot Metering Question

    Quote Originally Posted by Heroique View Post
    I thought a concrete example regarding "adjustments to development" might also be helpful…

    This is a chilly shot near Mount Rainier where I aimed for detail on two ends of a very wide zone range, so I chose compensation development to rescue the highlights.

    Here, the darkest tree-boughs were zone 3. The sunny dimpled snow was above zone 9.

    I used dilute HC-110 – that is, 1+123 direct from concentrate (not stock), and tray-developed for 19 minutes in 68° F, w/ a little bit of agitation every few minutes. All the snow has texture in straight prints from my Omega D2-v.

    Click image for larger version. 

Name:	Snowy peak.jpg 
Views:	56 
Size:	126.3 KB 
ID:	179391

    Tachi 4x5
    Schneider 150/9 g-claron
    Ilford FP4+ (in dilute HC-110) in trays
    Epson 4990/Epson Scan
    Heroique,

    Nice to see you posting! I haven't seen any posts from you in quite a long time and was wondering where you had gone. Glad to have your insightful comments here always.

    Best,

    Doremus

  5. #25
    Resident Heretic Bruce Watson's Avatar
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    Re: Average Spot Metering Question

    Quote Originally Posted by Doremus Scudder View Post
    Heroique,

    Nice to see you posting! I haven't seen any posts from you in quite a long time and was wondering where you had gone. Glad to have your insightful comments here always.

    Best,

    Doremus
    +1.

    Bruce Watson

  6. #26
    ic-racer's Avatar
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    Re: Average Spot Metering Question

    Quote Originally Posted by IanBarber View Post
    My usual method is to meter the shadows, meter the highlights, workout the brightness range and then adjust development if the brightness range is above 5 stops.

    For example, if the brightness range is 6 stops then I do N-1 development.

    Question:
    If I was to meter the shadows, meter the highlights and then make an exposure at the average of the two, what is actually happening. What I mean is, how will the tones be distributed.
    The exposure for B&W negative material should be based on the shadow value, per the physics of the film sensitivity characteristics and international standards achieved through empiric research. Averaging that value with another will randomly alter your exposure. Maybe more exposure, maybe less. Why would you want that for your negatives.
    If you are exposing transparency, then the situation is totally different. Averaging the values might help ensure the entire scene range fits on the film.

  7. #27
    Land-Scapegrace Heroique's Avatar
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    Re: Average Spot Metering Question

    Quote Originally Posted by Doremus Scudder View Post
    Heroique,

    Nice to see you posting! I haven't seen any posts from you in quite a long time and was wondering where you had gone. Glad to have your insightful comments here always.
    Quote Originally Posted by Bruce Watson View Post
    +1.
    Thanks for the kind words! It's a long story, but I do have a backlog of new landscape images to help illustrate it. Olympics and Cascades, of course. Look forward to catching up on the ever-helpful participation from both of you and so many others.

  8. #28
    Cor's Avatar
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    Re: Average Spot Metering Question

    My simplistic approach with B&W: try to find a flare free spot in the shadows (so not close to a bright spot ) were I still want detail in my print, measure, call it Zone III, open up 2 stops, and let the highlights land wherever they want. I take care of these when printing (dodging/burning or changing the grade). Works reasonably well for me.

    best,

    Cor

  9. #29

    Re: Average Spot Metering Question

    Cor, you mean you close down 2 stops (expose 2 EV less) than the meter reading of the Zone III area, right?

  10. #30
    Cor's Avatar
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    Re: Average Spot Metering Question

    Quote Originally Posted by consummate_fritterer View Post
    Cor, you mean you close down 2 stops (expose 2 EV less) than the meter reading of the Zone III area, right?
    oops..you are correct off course, thanks for noticing..

    best,

    Cor

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