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Thread: Metering Middle Grey

  1. #11
    tgtaylor's Avatar
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    Re: Metering Middle Grey

    I have the Schneider 4"x4" UV-410 (HAZE 1) filter that I paid around $150 new - they are currently priced at $161. It blocks UV below 410 nanometers "effectively reduces or eliminates photographic haze in areas where the atmospheric conditions contain a heavy concentration of dust particles, water droplets, and pollution...Helps eliminate such conditions often found in mountainous or coastal regions, and industrial areas that scatter light and produce a bluish cast that causes film to render a lack of color, contrast and overall image quality..." Would using this filter tone down the grey sky on the print mentioned above? A UV 2A filter is supposedly more effective.

    Thomas

  2. #12
    Drew Wiley
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    Re: Metering Middle Grey

    Jac, where on earth would one even find a "K2" filter these days unless they uncovered some Egyptian tomb beneath the dunes? Even that numbering system predates Egyptian hieroglyphics, I think. My point is, if someone does manage to find something like that, and does have the time to scrape the
    layers of mold and snail tracks off it, it's certainly not going to help the optical expectations associated with an expensive lens. And Tom - yes, UV filters
    can help clear a tad of haze scattering even on the coast using color film, but will be nowhere near as effective as a red or deep orange filter for pan film
    in that respect, which allow only long wavelengths through. And one shoe does not fit all in terms of the best filter for each specific type of color film.
    For example, I found that a nearly colorless very light yellow UV filter worked best for E100G chrome film at high altitude, whereas a pale magenta 2B
    worked best with Fujichrome, and a Singh-Ray KN pale apricot-salmon UV filter for Ektar color neg film. But even some of these product numbers have
    since changed to match the digital rather than film camera market. Ironically, certain kinds of expensive multi-coating can be counterproductive with
    certain digital sensors. Glad I don't have that problem; but I do believe in high-quality coated glass filters rather than flimsy fragile gels.

  3. #13
    Jac@stafford.net's Avatar
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    Re: Metering Middle Grey

    Quote Originally Posted by Drew Wiley View Post
    Jac, where on earth would one even find a "K2" filter these days
    Everywhere except under the rock under which you live.

  4. #14
    Drew Wiley
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    Re: Metering Middle Grey

    Ha! Didn't Wratten itself give up that numbering system twenty years before the Napoleonic Wars? Almost no one even markets them on a no.12 yellow label nanymore. Now filter names sound more like ice cream flavors: Sunkist Lemon Honeybee Yellow, maybe. Mine just says Hoya HMC Y, which is really closer to old no.8. Ho hum. What do you know about rocks, anyway? I thought in that part of the world they're called "erratics". If you want real rock formations, mountains, and glaciers those erratics come from, you'll have to head West. You can keep the loess.

  5. #15

    Re: Metering Middle Grey

    I have lots of Wratten gelatin filters in like-new condition.

  6. #16
    Jac@stafford.net's Avatar
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    Re: Metering Middle Grey

    Quote Originally Posted by Drew Wiley View Post
    Ha! Didn't Wratten itself give up that numbering system twenty years before the Napoleonic Wars? [...]

    What do you know about rocks, anyway? I thought in that part of the world they're called "erratics".
    My memory is likely as old as yours, and our rocks are not from the latest glacier era. We are known as the 'Driftless Area .' You must know of our dolomite.

  7. #17
    Drew Wiley
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    Re: Metering Middle Grey

    Now they call them Fruit Chewie sheets; and they sell for considerably less, digest easier too. True Wratten gels attracted less sugar ants. I use em mostly
    in the lab, not in the field, for specialized repro applications. I take good care of them, and fortunately bought certain Wratten items now almost impossible
    to find. The general photography items are easy to find; but I use glass filters for those kinds of applications. But some of them had set on a dealers shelf
    for a long time before I got ahold of them even forty years ago, and not a single one bears a letter designation, versus the current numerical system. Unfortunately, there's a big gap in my modest collection of official Kodak data guides. The 1947 book is all letter; then my 70's one is all numerical. But I tend to gravitate toward still older editions. I recently acquired a lovely Kodak field-use guide book bound in a thick leather cover, still in beautiful condition.
    It even contains actual viewing samples of popular Wratten filters set into pages, obviously letter-labeled back then.

  8. #18

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    Re: Metering Middle Grey

    I also agree that UV contribution to exposure would be low at sea level.

    In this (wiki) graph we see in red the sunlight spectrum at sea level, so it's easy to figure what exposutre contribution eliminated by an UV filter would be modest.

    The yellow graph shows the spectrum outside of the atmosphere, so in high mountain conditions we would have an intermediate situation.


  9. #19
    Drew Wiley
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    Re: Metering Middle Grey

    Jac - we had localized sheet glaciers only in the northern half of Yosemite Park (not Yosemite Valley itself), and in the Lake Tahoe Basin. The rest were either
    valley glaciers or the feeders of them up on the peaks, which have gradually receded, with far less remaining than just twenty years ago. There were ancient
    peoples crossing that terrain well before the post-Pleistocene thaw, who were obviously well adapted to it. But for about the last 10,000 or 11,000 years,
    as the canyons themselves thawed, the canyons themselves turned into camps and trails. Although the Sierras are mostly granitic, it does contain some
    spectacular metamorphic and volcanic sub-ranges. So it's not uncommon to find fascinating dark erratic boulders in otherwise white granite terrain. We never
    had loess like the Dakotas and upper Great Plains, but rather big alluvial plains at the foot of the mountains. These held vast herds of megafauna. Apparently
    big ice dams would burst far upcanyon and drowned thousands of animals at a time. We'd run into vast jumbles of camel, horse, and mastodon bones. Fossil
    ivory itself doesn't keep well except in permafrost, so tusks are very crumbly and difficult to recover intact. I once found an obsidian point embedded in
    fossil ivory, substantially older than anything found in North America before, though nowadays they're slowly finding things possibly just as old, maybe 18,000 yrs. It was pretty fascinating to study permafrost soil formations in areas that are now frequently above a hundred degrees F most of the summer.
    But wildlife photography would have been quite a challenge back when even a grizzly bear was a modest third-tier predator, and bulb-digging sloths were
    as big as bulldozers.

  10. #20
    tgtaylor's Avatar
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    Re: Metering Middle Grey

    Pere - I think that you graph shows that the Schneider 410 filter blocks all UV radiation up to the 410 mark. I gave this some thought yesterday afternoon and came to the conclusion that the filter would indeed tone down the grey sky in the aforementioned print. At least that is the working hypothesis which I am going to test at the next opportunity to re-shoot the courthouse. There are several UV filters currently on the market with different blocking bandwidths which would seem to indicate that one could fine tune an image. Also, the blue of a blue sky doesn't appear to be homogenous - it appears to have "hot spots" - and I think an appropriate UV filter will tend to smooth those hot spots out.

    Thomas

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