Sharpness and filters

Discussion in 'Exposure Discussion' started by Alan Klein, Mar 13, 2014.

  1. Alan Klein

    Alan Klein Member

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    I just started to shoot B/W from color on medium format. I added some top of the line B+W Schneider B/W filters. I used Tmax 100 developed in a pro lab in Xtol. I think I noticed that the sharpness when using the orange filter is not as good than without a filter. I'm looking at the results by scanning on a flatbed.

    Should I expect a loss in sharpness?
     
  2. RalphLambrecht

    RalphLambrecht Subscriber

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    sharpness is a combination of contrast and resolution.a clean filter won't affect eitherbutsometimes.filters can pick up a little surface fog,affectingimagecontrast.just make sure your filters are really cleanbefore using them.mine fog up from being kept in foam-padded jewlery containers and need occasional cleaningwith glass cleaner.:sad:
     
  3. darkosaric

    darkosaric Subscriber

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    Many people were swearing that filters degrade final image - so long time ago I did test yellow, orange and red filters - no loss on 30x40cm print visible against same lens without filter (testing lens was nikkor 50mm).
    As Ralph sad - they must be clean. And it looks to me that filters in general are bigger magnet for dust then lens alone.
     
  4. ROL

    ROL Member

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    Possibly a loss in sympathy, if your purpose is scanning. :laugh:

    As focal length increases, the high optical quality of filters becomes increasingly important, where image quality may be degraded by inferior glass or gels. I doubt that would be much of a factor with clean B&W filters. TMAX films would not be my choice for comparisons of sharpness. I hope you were at least comparing filter use using only TMAX examples. You might find more conclusive results with a high acutance developer like Rodinal or Pyro, on straight grain films. Lastly, your purpose for using moderately strong orange filtration on panchromatic films should be specific and rare, unless you are using artistic license with realistic tonalities. That, will otherwise degrade your images in far greater ways than simply putting more glass between the composition and the film.
     
  5. DREW WILEY

    DREW WILEY Member

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    Filters always affect sharpness. It's just a question of how much. It's one more set of air/glass interfaces. Basic optical science. It's one reason I only use the highest-quality multicoated filters. But in certain scenes, the apparent sharpness of a negative will actually improve simply because you might cut thru the UV or haze using an appropriate filter. Longer wavelengths are atmospherically scattered less than blue light, of course, so a red filter will often reveal details otherwise obscured by smoke or haze. Some films are susceptible to UV at higher altitudes, so a simply UV or skylight filter might help too. Then of course we use contrast filter to bring out certain things within a scene differentially. This
    might make a neg more contrasty in the sense we desire it, and hence appear better differentiated in the print itself; but this should not be
    confused with optical sharpness - nor should any of this.
     
  6. Richard S. (rich815)

    Richard S. (rich815) Subscriber

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    If you're handholding then your technique likely affects sharpness more than any clean and high quality filters would.
     
  7. ic-racer

    ic-racer Member

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    You could expect anything in that case. How about just looking directly at the negatives in question .
     
  8. DREW WILEY

    DREW WILEY Member

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    I happen to shoot 8x10 negs and chromes atop a heavy wooden Ries tripod, printed large Cibachromes for years so precisely that you'd need
    a loupe to see all the detail present in parts of the print, and know exactly what I am talking about. Somebody enlarging 35mm to anything
    even remotely as big has nothing to see up close anyway but a ball of mush and fuzz. But because you have to enlarge the neg or slide far,
    far more in that case, the effect of filter loss would be even more dramatic. The worst filters are polyester psedo-gels, followed by sandwich-style Tiffens, then old-school true gels. But I can tell the difference even using the best multicoated ones. But when you need filters you need them - and that happens to be quite often in my case. Another nice thing about MC glass filters is that they resist smudges and condensation better than plain glass, so this in itself helps them stay sharper.
     
  9. Jim Noel

    Jim Noel Member

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    You won't get your answer on a scanner and computer screen. You need to make a good wet print.
     
  10. momus

    momus Subscriber

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    A yellow or red filter will give you more contrast, so whatever sharpness will be lost (negligible in my experience) will be offset by the increased contrast. It's a wash. Orange filters are odd ducklings, at least around here. They change the look of B&W so drastically that I prefer not to use them. Good for portraits maybe. I think they don't add contrast like the yellow and red, so compared to those two, my photos may LOOK less sharp w/ an orange filter.

    I've used very cheap filters and very expensive ones, and never saw a cat's whisker of difference between them. As for flare, keep a good hood on the lens and it doesn't matter. Other people may have different experiences, this is mine.
     
  11. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member

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    I sometimes use an orange filter. It will darken the sky more than yellow, less than red, and darkens foliage more than yellow. Adding two air/glass surfaces can reduce contrast slightly due to flare (flare from the subject itself and reflections between the filter and the front element of the lens, which are not affected by a hood, though one should always use a hood for other reasons), but orange generally increases contrast with B&W film, and reduces chromatic aberration by cutting out other wavelengths, so with B&W film, a strong monochromatic filter can actually increase resolution, depending on how well corrected the lens is.
     
  12. DREW WILEY

    DREW WILEY Member

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    Yes indeed. Older lenses were not always corrected across the spectrum, so what I stated previously could be wrong in such cases, specifically
    when you're going back far enough that the lenses were not classified as "color (film) corrected" at all. Cutting off the tertiary wavelength (generally the blue) would improve performance even with black and white film. Such anomalies basically involve antique lenses, though some
    of these have qualities much desired today, esp by large format contact printers.
     
  13. L Gebhardt

    L Gebhardt Subscriber

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    I will echo the idea to check the filters for haze. I had a filter wallet that would fog the filters quickly. I think the plastic from the dividers outgassed and deposited on the filters. I switched wallets and the haze went away (after a cleaning). The haze certainly contributed to softer prints, but at least was so bad most of the time I noticed it just pulling out the filter.
     
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  15. cliveh

    cliveh Subscriber

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    I'm sure filters don't make an iota of difference to the image, but being a mad purist I never use them.
     
  16. DREW WILEY

    DREW WILEY Member

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    Yeah, Larry ... anything vinyl will outgas. Just look at the inside of a windshield above the vinyl dashboard. Plasticizers are voodoo to optics.
    But multicoated glass resists even that kind of smudge better than plain glass because there is less to cling to.
     
  17. Poisson Du Jour

    Poisson Du Jour Member

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    Have you scrutinised the negative with a 4 to 8x loupé, or passed judgement on the sharpness by some other means e.g. holding neg up to light? A finished drum scan will give an overall impression on the definition of a lens and film, but all that is useless if an average lens, poor technique and even poorer scanning conspire to derail assessment.

    I used an orange filter in my student days with Plus-X almost three decades ago and cannot recall any sharpness derangement issues from what was printed and exhibited in those days, even with the rather lowly standard of filters available way-back-when. Today we are fortunate to have so many exceptionally high quality filters available. B+W filters will not introduce a lack of sharpness, but resin filters will, and I have never stooped to use those things with any highly corrected lens. With all filters there is an increased risk of flare (exceptionally well controlled with today's multicoated filters) and, where more than one is in use (not recommended), ghosting and a loss of contrast. You could of course keep shooting without an orange filter e.g. try a red filter.
     
  18. BrianShaw

    BrianShaw Member

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    Momus x2
     
  19. Xmas

    Xmas Member

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    ditto but sharpness is like grain...
    double shot of coffee just as likely
    even an aspherical lens will be improved by a deep coloured filter if you are using slow film and heavy tripod mirror lockup...
     
  20. Doremus Scudder

    Doremus Scudder Member

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    Personally, I'd be looking elsewhere for the cause of your softness (after making sure the filters were clean, of course).

    Good quality coated filters do indeed add more air-to-glass surfaces, but the effect is not only negligible, but no different than switching from a 4-element to an 8-element lens... While I will certainly grant the point to Drew and others that adding a filter to a given lens will affect image contrast in the shadows and maybe sharpness to an extent, I would imagine that there are more quality variances between the myriad of different taking lenses out there than would be introduced by adding a quality, coated filter.

    And, there certainly should not be any difference in sharpness between shots taken with different color, but similar quality, filters.

    Camera/subject movement, poor focus, poor scanning, etc. all seem to me to be more likely culprits.

    FWIW, I've never heard anyone say anything like, "Oh, that 16x20 print is a bit unsharp; the photographer must have been using a filter!"

    Best,

    Doremus
     
  21. DREW WILEY

    DREW WILEY Member

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    This whole topic can be definitely proven on an optical bench. But otherwise, it's common sense. I can even tell when wearing a smudged or
    cheaper pair of reading glasses that something is off, compared to a recently cleaned good pair. How much does it matter? Just depends. I'm
    of the school of thought that these little things tend to add up. A minor compromise here and there, and eventually it really does show in the
    print. But not everyone has the same priorities. What I categorically deny is that filter quality is not a factor. Every filter manufacturer knows
    that! I could same about the lens analogy above: If you've ever owned a multicoated dagor lens with only four air/glass interfaces no way
    your eyeballs won't pop out (I know, hyperbole- but you get the point), compared to a plastmat, not to mention some zoom lens with sixteen
    or seventeen separate elements. I really really does make a difference, and if everything else in the workflow follows suit, even the public
    will quickly perceive something, even if they can't explain it. Happens all the time to me. But a misaligned enlarger, or cheapo lens on that,
    why bother....?
     
  22. Alan Klein

    Alan Klein Member

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    For what it's worth, I was using a 180mm Mamiya Secor C lens on an RB67 MF camera with mirror locked up on a heavy Gitzo tripod. The filters were multicoated B+W MRC just bought-right out of their shipping containers. I was comparing shots taken with and without the filter, but they were different scenes. Probably has to do with that rather than equipment or, I hope, operator error. I'll shoot some more and compare similar scenes, with and without filters. Thanks for all your help.
     
  23. Doremus Scudder

    Doremus Scudder Member

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    Drew,

    I agree wholeheartedly.

    The OP was talking about multi-coated B+W filters, which are as good as it gets for filters; plano-parallel Schott glass and top-notch coating. The effect of using one of these, when you have to, would be negligible. Sure, a lot of "negligibles" will add up to a tangible, but we were just talking about filters. The real question was if a particular color (orange) itself was responsible for degrading the quality of the image. I rather think not. The culprit is likely something else besides the color of the filter.

    As to craftsmanship and careful working: Yes, don't use cheap and uncoated filters, get the best optics you can afford, etc., etc. I'm way with you there. I replaced all my pretty-good filters with B+W filters some time ago.

    On the other hand, if you are a careful worker and the need arises to use a bit-less-than-optimum-quality filter, that alone is not going to make a noticeable difference in the final result; it is only one "negligible."

    And, sometimes, "good enough" is really good enough. The best modern lenses are indeed superior to much of what was used in the past. We have things available to us that were not available (or affordable) for the likes of Adams, Weston, et al. Nevertheless, they made the best of what they had and some rather good images as well...


    Best,

    Doremus
     
  24. Richard S. (rich815)

    Richard S. (rich815) Subscriber

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    Because I shoot more than test patterns posted on a wall I would disagree heavily with this statement. In fact I avoid most modern glass and actually do not find it superior at all. But perhaps that's the subject for a different thread someday...
     
  25. Poisson Du Jour

    Poisson Du Jour Member

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    OMG...
     
  26. Doremus Scudder

    Doremus Scudder Member

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    Richard,

    Let me qualify :smile:

    I'm talking about optimizing resolution and contrast here, nothing more. There's really no question that modern computer-aided designs and multi-coatings coupled with more stringent quality control and assembly procedures have resulted in a general improvement in these parameters when compared with single or uncoated lenses that were hand assembled and designed "on paper." Whether you like that or not or whether you call that "quality," is another issue.

    The OP's question was about whether a particular color of filter would degrade contrast and sharpness more than another. That is what I was addressing, not aesthetic issues.

    FWIW, there were/are a lot of older lenses that don't fit this generality; I love my Ektars and there are those who swear by the Red-dot Artars, etc. etc.

    Best,

    Doremus