Pro 160S color fringing

Discussion in 'Film and Processing' started by donald_ingram|1, Jul 9, 2006.

  1. Hi, I originally posted this on the Leica Forum as I was checking out a Zeiss ZM 50mm lens for the first time, and was concerened it was at fault
    Zeiss ZM50 - color fringes - would you expect better ?
    I believe I have eliminated the scanner from the equation, and the lens sharpness is extremely good
    Has anyone experienced similar color fringing around high contrast edges on Pro160s ?
    00HEsT-31088984.jpg
     
  2. Here is an optically printed enlargement - there is obvious bleeding around the roof line of these buildings with whitewashed walls.
    00HEsZ-31089284.jpg
     
  3. Maybe it's just me, but I think the colour fringing you are refering to is so slight I don't really care. If the image is sharp corner to corner, you can be certain the lens is perfectly aligned. I really don't know what the fuss is about, in practical sense, I have seen much worse CA (not digital PF). Seeking for perfection is such a painful experience sometimes.
     
  4. I don't think the film has anything to do with it and the image looks fine to me.
     
  5. Gut instinct (and an admittedly less than complete knowledge of film) tells me it's the lens,
    not the film, and hardly a serious-looking problem at that, but for my own edification I'd
    throw in one question for the film experts: could this be down to the behaviour of the anti-
    halation layer?
     
  6. I think your first image is about as good as can be expected from current 35mm film. One thing I've noticed is that the newer emulsions tend to emphasize low grain over sharpness. I can certainly see why this is a desirable characteristics especially for a portrait film like 160S. If you're after sharpness, try the old Kodak Gold 100. It cuts like razor after a little digital filtering.
    00HFY0-31106684.jpg
     
  7. 100% crop, unmanipulated straight from the scanner.
    00HFY8-31106784.jpg
     
  8. Same crop as above, but post-capture digital filters. Note white table in foreground, and window frames. Maybe a little much?
    00HFYC-31106884.jpg
     
  9. 100% crop from another section of the frame.
    00HFYD-31106984.jpg
     
  10. It's chromatic aberration, which is from the lens.

    Look at close-ups of white lines in all four quadrants of a test image: You'll see that the color shift directions vary from quadrant to quadrant.
     
  11. I'm going to agree that it's unrealistic to expect a lens ( or film ) to be perfect under such
    scrutiny.

    Dan, I cannot see a shift in the few samples I have, but I believe it is a likely cause - next
    time a suitable subject comes into view I will check it out.

    Robert, I never know what Kodak film is which, the seem to rename things too often and
    have market specific variations. UC100 does not seem to be available in the UK : elite
    colour 200 is - I tried UC 200 once it was very creamy, low grain but not as sharp as the
    pro160s. Your scans have the bite that I like - accutance that makes film stand out from
    digtal.

    All this pixel peeking stuff just gets worse the more I look.

    I'm just going to load the camera up with Tri-X or NPH, get out and take some normal
    pictures
     
  12. Donald, your second photo reminds me a lot of Glasgow. (shot in the dark.)
     
  13. Gold 100 is (was) Kodak's standard consumer film, emulsion code GA. This is the stuff that used to hang on drug store film racks for $1.20USD per 24 exposures. The formulation probably hasn't changed in 30 years. Newer films (100UC, 160S, Reala, etc.) are all superior to this in most respects except one: Gold 100 is sharper. I've attached the MTF curves from the datasheets for 160S and Austrian version of Gold 100 (supposedly the same film save for a color balance tweak.) What you'll notice is that 160S drops below MTF100 at 20 cycles/mm, while Gold 100 doesn't do this until 50 cycles/mm. More importantly, Gold 100 has dramatically boosted acutance (much higher than 100% MTF) from 7 cycles/mm onward. Frankly, the best way to realize high sharpness is to shoot a larger film format. Transitioning from 135 to 6x7 MF, for example, roughly doubles the linear resolution: much more of the image is then recorded at the high MTF response regime of whatever film you choose. Nothing quite beats a larger imaging area to cover the failings of both emulsion and optics. By the way, checkout the MTF curves for reversal films. It'll surprise you. That creamy smooth low grained transparency costs elsewhere.
    00HGOJ-31128184.jpg
     
  14. If you want sharpness, ditch the color neg film and go with something like Provia or Velvia. You'll get finer grain as a bonus.
     
  15. I don't think Gold 100 has *been* around for 30 years... maybe 20, though. The stuff my mother shot in the late '70s and early '80s was called Kodacolor 100. It had a very nice look, but the negs have faded noticably over the years.

    There was a rumor floating around on here a while back that the current incarnation of Gold 100 is actually based on Gold 200, but with a neutral dye added to slow it down to 100. I can't recall whether anybody was able to confirm or deny whether that's actually true or not. Similar rumors have circulated in regards to 100UC and HiDef 200/RoyalSupra 200/EliteColour 200.
     
  16. I thought Ron Mowrey had said in the past it's not true.
     
  17. Most slide films have lower sharpness than Kodak Gold 100, perhaps
    because print films were designed to emphasize edges when making enlargements.

    It seems likely that Gold 100 scans + NeatImage (or equivalent)
    can produce far better results than Fuji 160S.

    On the original topic, I agree with Dan Schwartz that this is
    chromatic aberration from the lens.
     

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