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Thread: Merering: Spot Metering, Reflective, Gray Card, Average

  1. #11

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    Re: Merering: Spot Metering, Reflective, Gray Card, Average

    Shadow areas which you'd like to record with some detail should typically be placed on zone 3 or very close to this. After this it is basically good to meter the highest highlight value for which you'd like detail and if this value is above about a zone 8...you may need to shorten your film development time a bit.

    Basically, just remember that shadow values tend to develop more fully within a shorter time period than do highlight values, which is why you will usually set your desired shadow values by means of actual exposure...and then adjust your desired brightest (detailed) highlight values (which will typically keep gaining in intensity as development time increases) by adjusting development time and/or agitation and/or solution strength and/or solution temperature.

    But there are loads of variations on this depending on how you are responding to a particular subject, what type of film you are using, filtration, etc.

    Another thing to remember is that there are often various "micro densities" present within very small areas which are very difficult to meter accurately, and which may present as a slightly broader total visible density range than that which you think you've chosen by exposure and development alone. I often welcome these micro densities as they can add a bit of subtle "sparkle" to a print.

  2. #12
    Drew Wiley
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    Re: Merering: Spot Metering, Reflective, Gray Card, Average

    Assuming we're still talking about a studio scenario, lighting ratios can be balanced to match the scale of the film. Yes, ZS theory works fine for black and white film. But with color film, a priority must be set on how you want colors to saturate. Given the short scale of chrome film, diffuse softbox conditions are generally desirable. A truly accurate 18% gray gray reference temporarily in the scene tells you the correct midvalue the film is engineered to. Besides this, check your highlights and shadows with the spotmeter too for range fit, especially if you've added an accent light.

  3. #13

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    Re: Merering: Spot Metering, Reflective, Gray Card, Average

    Having just shot some still lifes and made a contact sheet and some work prints, my experience says “bracket.” While I have my film speed and development pretty well zeroed-in outdoors, indoors both bellows extension and reciprocity come into play. While I have calculated factors for both, first the measurements don’t necessarily line up with my tables, so I have to interpolate intermediate values. Secondly I have a number of different reciprocity tables for the same film (in my case HP5+). Bottom line, it is worth exposing a sheet above and below the calculated exposures if you really like the still life subject.

  4. #14
    Drew Wiley
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    Re: Merering: Spot Metering, Reflective, Gray Card, Average

    Bracket? It might be a good idea with a new setup or unfamiliar film; but it makes more sense to do that kind of preliminary homework on a roll of 35mm or 120 film. If color film is involved, with 8x10 now over $30 per shot with processing, one would hope a person had acquired enough competence first, rather than taking out a second mortgage on the house just to afford bracketing. If black and white film, any studio setup should allow enough wiggle room in the exposure to give a reasonably variable interpretation of the negative when printing. If I simply had to bracket (which I have never found necessary with any kind of sheet film), I'd at least scale back to 4x5 to prevent breaking the piggy bank. Yes, any transition to a new style of metering has a learning curve; but any bugs can be ironed out with far cheaper roll film bracket tests
    to establish basic exposure latitude and lighting ratio parameters.

  5. #15

    Re: Merering: Spot Metering, Reflective, Gray Card, Average

    Quote Originally Posted by John Layton View Post
    Shadow areas which you'd like to record with some detail should typically be placed on zone 3 or very close to this. After this it is basically good to meter the highest highlight value for which you'd like detail and if this value is above about a zone 8...you may need to shorten your film development time a bit.

    Basically, just remember that shadow values tend to develop more fully within a shorter time period than do highlight values, which is why you will usually set your desired shadow values by means of actual exposure...and then adjust your desired brightest (detailed) highlight values (which will typically keep gaining in intensity as development time increases) by adjusting development time and/or agitation and/or solution strength and/or solution temperature.

    But there are loads of variations on this depending on how you are responding to a particular subject, what type of film you are using, filtration, etc.

    Another thing to remember is that there are often various "micro densities" present within very small areas which are very difficult to meter accurately, and which may present as a slightly broader total visible density range than that which you think you've chosen by exposure and development alone. I often welcome these micro densities as they can add a bit of subtle "sparkle" to a print.
    Thanks for the tips, really helpful.

    "Shadow areas which you'd like to record with some detail should typically be placed on zone 3 or very close to this. After this it is basically good to meter the highest highlight value for which you'd like detail and if this value is above about a zone 8...you may need to shorten your film development time a bit." – When you do meter the desired shadows and meter desired highlight values, do you then average this to get that final reading?

    "Basically, just remember that shadow values tend to develop more fully within a shorter time period than do highlight values, which is why you will usually set your desired shadow values by means of actual exposure...and then adjust your desired brightest (detailed) highlight values (which will typically keep gaining in intensity as development time increases) by adjusting development time and/or agitation and/or solution strength and/or solution temperature."– this is very helpful to keep in mind, did I get that right? Relatively speaking and all factors considered, by increasing or decreasing development times, you tend to push or pull the highlights yeah? The same goes for increasing agitation (more highlights), stronger solution mix (more highlights), and higher temperature (more highlights).

  6. #16

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    Re: Merering: Spot Metering, Reflective, Gray Card, Average

    What John has given you is excellent information, but I believe and correct me if I'm wrong John. Meter the shadows, stop down 2 stops (zone 3), or Shorten your shutter speed by 2 speeds(has the same affect). That is your shutter setting. I believe what John is saying is to meter the highlights to determine if you will need to adjust your development IF the highlight meter reading is above Zone 8. You should not average highlights and shadows to determine exposure. Expose for the shadows and develop for the highlights. For the second part of your response I would not play around with stronger developer, temp, or agitation, these are aspects that you should standardize. Only adjust the development time. Time is the only thing that is absolutely consistent. After you get a standard process down with consistent results you could play around with other things. Just another suggestion.

  7. #17

    Re: Merering: Spot Metering, Reflective, Gray Card, Average

    Quote Originally Posted by McSnood View Post
    What John has given you is excellent information, but I believe and correct me if I'm wrong John. Meter the shadows, stop down 2 stops (zone 3), or Shorten your shutter speed by 2 speeds(has the same affect). That is your shutter setting. I believe what John is saying is to meter the highlights to determine if you will need to adjust your development IF the highlight meter reading is above Zone 8. You should not average highlights and shadows to determine exposure. Expose for the shadows and develop for the highlights. For the second part of your response I would not play around with stronger developer, temp, or agitation, these are aspects that you should standardize. Only adjust the development time. Time is the only thing that is absolutely consistent. After you get a standard process down with consistent results you could play around with other things. Just another suggestion.
    Thanks for summarising, yes got those points. Good stuff!

    I believe what John is saying is to meter the highlights to determine if you will need to adjust your development IF the highlight meter reading is above Zone 8. You should not average highlights and shadows to determine exposure. Expose for the shadows and develop for the highlights.

  8. #18
    Drew Wiley
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    Re: Merering: Spot Metering, Reflective, Gray Card, Average

    The Pentax digital spotmeter has a scale of the rim which makes it very intuitive to place your shadow and highlight reading relative to the 18% Z5 red triangle, which indicates your correct exposure. This is not an average. You place your desired shadow placement 2 or 3 EV below this, depending on the specific film, check your highlights values, and accordingly adjust development for the highlights. But in a studio you can simply balance the lighting to fit the scale of the film.

  9. #19

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    Re: Merering: Spot Metering, Reflective, Gray Card, Average

    Quote Originally Posted by jurgenestanislao View Post
    ... When you do meter the desired shadows and meter desired highlight values, do you then average this to get that final reading?
    Nope. Base your exposure on the shadow value. Averaging high and low readings can lead to underexposure when the subject brightness range is great. Overexposure if the SBR is small. You measure the highlight to know if there will be a problem there and if you have to adjust development time to compensate. If you never change development time, then you don't even need to meter the highlight; just deal with the contrast when printing. Many do.

    Quote Originally Posted by jurgenestanislao View Post
    ... ... Relatively speaking and all factors considered, by increasing or decreasing development times, you tend to push or pull the highlights yeah? The same goes for increasing agitation (more highlights), stronger solution mix (more highlights), and higher temperature (more highlights).
    Shadows develop completely in the first third or so of development. Highlights keep developing until we stop them. Film is hardly ever developed till it's finished; we stop development when the highlights get to the point we like. Less development = less dense highlights ("pulled" if you like, but I dislike the term). More development = more dense highlights ("push," but...). The shadows don't change much with changes in development; that's why we base exposure on the shadows.

    You can get more development by increasing time, temperature, dilution strength, etc. but best practice is to establish a good agitation regime and a standard temperature and simply adjust the time of development to change things. Tweaking agitation can affect evenness of development. Tweaking temperature is a lot less controllable, so stick with time changes.

    Doremus

  10. #20

    Re: Merering: Spot Metering, Reflective, Gray Card, Average

    Quote Originally Posted by Doremus Scudder View Post
    Nope. Base your exposure on the shadow value. Averaging high and low readings can lead to underexposure when the subject brightness range is great. Overexposure if the SBR is small. You measure the highlight to know if there will be a problem there and if you have to adjust development time to compensate. If you never change development time, then you don't even need to meter the highlight; just deal with the contrast when printing. Many do.



    Shadows develop completely in the first third or so of development. Highlights keep developing until we stop them. Film is hardly ever developed till it's finished; we stop development when the highlights get to the point we like. Less development = less dense highlights ("pulled" if you like, but I dislike the term). More development = more dense highlights ("push," but...). The shadows don't change much with changes in development; that's why we base exposure on the shadows.

    You can get more development by increasing time, temperature, dilution strength, etc. but best practice is to establish a good agitation regime and a standard temperature and simply adjust the time of development to change things. Tweaking agitation can affect evenness of development. Tweaking temperature is a lot less controllable, so stick with time changes.

    Doremus
    Thanks for being patient with my queries, really appreciate it.

    On a last clarification–when you say metering shadows, you're referring to shadows where you prefer to retain detail yeah?

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