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Thread: Color correction filters for transparency film?

  1. #21

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    Re: Color correction filters for transparency film?

    In smokey areas these days, better have some heavy cooling (barely used) 80C daylight to tungsten conversion filters!!!

    Steve K
    Last edited by LabRat; 13-Sep-2020 at 17:29.

  2. #22
    Drew Wiley
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    Re: Color correction filters for transparency film?

    I love the amber light of this smoke. Makes me feel like I'm in a Godfather movie. I just don't want to be out breathing it.
    Chrome films results are easy to judge over a good light box. I used a color temp meter and cc filters only for making master transparencies to calibrate batches of color paper and related critical lab purposes, or under artificial indoor lighting situations when there was a mismatch. It's been a long time since batch variation in chrome films themselves carried recommended starting filter corrections on the box, and even then, landscape photographers largely ignored that. Many even liked the way old style Ektachrome 64 especially exaggerated blues when uncorrected.
    Color neg film is a different story, and especially the one I use most, Ektar. I have a selection of corrective filters I routinely carry for that in order to counteract potential cyan crossover in shadows and overall balance issues. I don't carry the color temp meter with me because I already know what to expect from previous testing and printing experience. This particular CN film is designed to give a more balanced saturated look similar to chrome films, so isn't artificially warmed like portrait-friendly ordinary color neg films.
    My routine default filter is a Hoya light pink 2A skylight filter for minor overall correction. If there's bluish cold overcast, I use a slightly stronger pink-amber Singh-Ray KN (which is a bit better than a KR1.5, which in turn is a bit redder and better than an 81A; but all are usable for this situation). I rarely use an 81B, but do sometimes use a special Tiffen filter which behaves like an 81B and 2A combined, which helps balance out the cyan over-reaction to what are in fact blue shadows in open sun situations; otherwise, a KR3 is preferable to an 81C in similar conditions; but I own them all for slightly different reasons. I even made a couple of special flashing attachments for differentially correcting shadow versus highlight conditions in open sun, but they're clumsier and less predictable to use. The only cc filter I use in the field is an 05M for selectively cutting green out of the blues, and hence the risk of cyan crossover. Of course, I never carry ALL these filters at the same time, just a few I anticipate needing for specific conditions.

  3. #23
    http://www.spiritsofsilver.com tgtaylor's Avatar
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    Re: Color correction filters for transparency film?

    I don't believe that it is necessary to use a filter with color negative film as you "color correct" when printing. Back in '97 when comet Hale Boop was at its brightest I shot an eyepiece projection photo of the comet's very active nucleus on color negative film with a K1000 camera and had it processed and printed at one of those ubiquitous one hour photo labs. The resulting print was all an all green comet and didn't show the structure of the nucleus which was very dynamic in the eyepiece. This was before my film printing days and I showed the print to Dr. Fraknoi at Foothill college who, at the time, gave popular public lectures on astronomy. He couldn't (or wouldn't?) explain the color either. Now, of course, that should be an easy color correction in the enlarger. If you ever get the chance, do observe the nucleus of a comet through a high power eyepiece - I believe that I was using a 25mm eyepiece on 10" f10 telescope.

  4. #24
    Land-Scapegrace Heroique's Avatar
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    Re: Color correction filters for transparency film?

    Quote Originally Posted by shutterboy View Post
    Do large format landscape photographers, shooting mostly slide film stocks, use [color meters] and color correction filters? If yes, then under what scenarios?
    I've used a Sekonic color meter at Glazers Camera in Seattle (their meter) to test B+W's 10-stop ND filter – which had been proving in my experience to be anything but "neutral" in the field for transparencies. (I often use this 52mm filter with my Fuji A 240mm/9 and Schneider 150mm g-claron with thread adapter.)

    The goal was to determine what single filter might bring the B+W back to "neutral."

    According to the Sekonic meter, the B+W caused a 970 K drop in temperature (more red). This was even more than I suspected, and I’d call it significantly un-neutral! More technically, we had a chart that equated this change w/ a +40 nm shift.

    BTW, for comparison I also had a Nikon 2-stop and Tiffen 3-stop ND filter, and we measured these, too. The Nikon produced a 160 K rise in temperature (more blue). The Tiffen produced a 340 K rise (also more blue). These changes, of course, would not be as noticeable to the naked eye (if at all).

    Then we measured some “correction” filters that might be a good match for the B+W.

    The B+W’s 970 K drop suggested an 80d filter (which typically raises the temperature about 1300 K or so) would be a good place to start.

    Below is Lee's approximation of what an 80d filter looks like:

    Click image for larger version. 

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    Glazers had a Lee resin 80d on hand, and the Sekonic said it actually added about 1,000 K.

    And indeed, I've discovered the Lee 80d is a good "in the ballpark" correction for the B+W, good enough for enjoying finished slides on an overhead projector – while if I scan and go to PP, I do commonly add a touch of warmth.

  5. #25

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    Re: Color correction filters for transparency film?

    Yea Drew, the smokey amber light would be great for one of those surfing "endless summer" sunset photo shoots, and you wouldn't have to wait for sunset... ;-)

    Just add longboards...

    Steve K

  6. #26

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    Re: Color correction filters for transparency film?

    Quote Originally Posted by tgtaylor View Post
    I don't believe that it is necessary to use a filter with color negative film as you "color correct" when printing. Back in '97 when comet Hale Boop was at its brightest I shot an eyepiece projection photo of the comet's very active nucleus on color negative film with a K1000 camera and had it processed and printed at one of those ubiquitous one hour photo labs. The resulting print was all an all green comet and didn't show the structure of the nucleus which was very dynamic in the eyepiece. This was before my film printing days and I showed the print to Dr. Fraknoi at Foothill college who, at the time, gave popular public lectures on astronomy. He couldn't (or wouldn't?) explain the color either. Now, of course, that should be an easy color correction in the enlarger. If you ever get the chance, do observe the nucleus of a comet through a high power eyepiece - I believe that I was using a 25mm eyepiece on 10" f10 telescope.
    I shot that comet in B/W, but later found out the tail was 2 colors in green and blue...

    I thought there was a defect in the Tri-X I shot as there was a couple of grain clumps/halation next to the nucleus, but I called the city astronomer, and he said they were excited the comet nucleus was breaking/shredding material, so guess what that "grain" was???

    It took months of work to build an astro rig (while I was recovering from a serious flu illness), 2 weeks shooting under difficult conditions including heavy haze coming in right after 15 minute exposure started started, a wave of mosquitos, a heavy tripod metal breaking from fatigue, had to hand track with mount with one big knob, desert trips, another film defect involving loose lint on new 35mm film cassette, and more)... But ended up with ONE perfect frame!!!

    A great amount of trouble, but that's why we do it...

    Steve K

  7. #27
    Drew Wiley
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    Re: Color correction filters for transparency film?

    Tom - what I stated is absolutely correct. The proof is in the pudding - bowl after bowl of it. Please note that I made specific reference to Ektar, but it applies to a lesser degree to other color neg films too. Every serious Hollywood cinematographer knows it; otherwise, they wouldn't get the job. Unless the risk of crossover is corrected at the time of the shot via filtration, you cannot realistically post-correct it by any ordinary simple means. There are a few rather complicated cures involving intermediate tricolor separations.
    Overlapping parts of separate dye curves create what I call "mud". That tendency is deliberately engineered into low contrast portrait films, which is exactly why they can't differentiate related hues well - everything similar wants to become a generic "pleasing skintone". Ektar was engineered to render cleaner colors overall more like chrome film instead, but suffers from cyan crossover.
    All you can do with colorhead control is an overall balance adjustment, not un-mix mud once it's formed. Post-correcting in PS is not very realistic either. People who claim that they can do that have probably never seen a "clean" color print in their life; and theirs sure aren't.
    Hale Bopp - wasn't that an early rock n' roll band, Halley and the Comets? I could barely make out the darn thing here. Up at my place in the Sierras one could see even the tail of it a third of the way across the sky with the naked eye. Once I saw the polar ice cap on Mars using just an ordinary pair of binoculars atop Sonora Pass. The serious astrophotog hobbyists haul big trailers up to the crest of the White Mtns around 11000 ft where the air is really clear. I've seen 16 inch reflector telescopes up there. Some of their mounts cost more than the truck that hauled it there.
    Last edited by Drew Wiley; 14-Sep-2020 at 17:08.

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