Ping Bruce - re that 300mm L lens

Discussion in 'Digital SLR' started by eatmorepies, Nov 5, 2010.

  1. eatmorepies

    eatmorepies Guest

    Hello

    Reference my 300mm f4L IS with the disappointing performance. I was packing
    the lens to send to a Canon Service Centre and decided to shoot some snaps
    to show them how poor it was. To do this I removed the filter - hey presto -
    vastly better images.

    Today I have been shooting various test pictures - including the sloping
    ruler type to check micro focus adjust. You can argue there is a little more
    depth of field distance symmetry when the focus is set on +2. The lens
    itself seems to be performing properly.

    I've uploaded a couple of crops onto my flickr page. Here;

    http://www.flickr.com/photos/[email protected]/

    It's a murky old day so I was on ISO 1600 (Canon 1D mkIV). Both had 90%
    unsharp mask applied in CS5.

    I'm going to take some real world snaps at a hedging competition and an
    enduro this weekend before taking any decision on recalibration. The real
    test will be at the rugby next weekend.

    I always fit a filter (UV) to an expensive lens - I'd better review this
    policy. I'm off to test some of my other lenses with and without their
    filters - although the other L lenses I have all seem nice and sharp, so
    it's probably a single rogue filter.

    Cheers

    John
     
    eatmorepies, Nov 5, 2010
    #1
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  2. eatmorepies

    Ofnuts Guest

    The cost of a protective filter sufficiently good to be unnoticed on the
    pictures is greater than the price of the lens times the probability to
    have an accident where the filter would have been useful. Especially on
    teles that have a fairly deep hood.
     
    Ofnuts, Nov 5, 2010
    #2
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  3. eatmorepies

    Bruce Guest


    Wow! A surprising result.

    The $64,000 question has to be, what brand and type of filter were you
    using? I'm a believer in using protective filters because I shoot a
    lot of images on construction sites and there is a lot of grit flying
    around. But it means buying top quality filters - especially for
    digital - and they can get very expensive in larger diameters,
    although they are still a small fraction of the cost of replacing a
    lens's front element.

    Most of my filters are from B+W and Nikon, but I still have a couple
    of Hama filters from the days when they were made in Germany using the
    same Schott glass as B+W and Heliopan. Nowadays, Hama filters are
    made in Japan and they aren't nearly as good.
     
    Bruce, Nov 5, 2010
    #3
  4. eatmorepies

    Bruce Guest


    Are you sure it wasn't a softening filter? I have Zeiss Softar I and
    II soft focus for all the lenses that I use for portraiture, and the
    effect of a Softar I is probably similar to the filter you were using.
     
    Bruce, Nov 5, 2010
    #4
  5. eatmorepies

    eatmorepies Guest


    This is a Hoya multicoated UV(N). I've got Hoya filters on all my other
    lenses. I tried a different filter (same brand) on the 300mm and that
    produced slightly softer images than without a filter but not as soft as the
    original filter I was using. I tried with and without filter tests on my
    24-105L, the filter made no discernable difference. I shall try the same on
    my other 77mm filter lenses.
     
    eatmorepies, Nov 5, 2010
    #5
  6. As do I, when possible...

    Likely. Among MANY Nikkor and Hoya filters, I have seen only one
    "bad" one, a Nikkor that had a very slight power that caused a 200mm
    Nikkor to not reach infinity focus. Tiffens were a different matter, though...

    Not really. Once in a great while, these things happen... :-(
    Test, test, test immediately after purchase.
    The greatest differences will show on your longest FL lens with the widest
    stop, shot wide open. I have compared (on a 400mm f3.5 Nikkor) no filter,
    rear filter only, front filter only, and both front and rear filters in place (with
    Nikkor filters, and refocusing as necessary). No differences were noted with
    careful viewing.
    --DR
     
    David Ruether, Nov 5, 2010
    #6
  7. Unless you work in an environment where you have flying sand,
    salt, mud, etc. and/or need environmental sealing and the lens
    requires a filter to do that. Or where animals are apt to
    put wet snouts and paws right on the front element. :)

    BTW, Canon offers "Protection Filters" for exactly that reason ---
    no need to use UV filters.

    -Wolfgang
     
    Wolfgang Weisselberg, Nov 5, 2010
    #7
  8. You may find this page interesting, John:

    http://www.clarkvision.com/articles/evaluating_filter_quality/index.html

    and others on Roger's site:

    http://www.clarkvision.com/articles/

    Cheers,
    David
     
    David J Taylor, Nov 5, 2010
    #8
  9. eatmorepies

    Robert Coe Guest

    : > The cost of a protective filter sufficiently good to be unnoticed on the
    : > pictures is greater than the price of the lens times the probability to
    : > have an accident where the filter would have been useful. Especially on
    : > teles that have a fairly deep hood.
    :
    : Unless you work in an environment where you have flying sand,
    : salt, mud, etc. and/or need environmental sealing and the lens
    : requires a filter to do that. Or where animals are apt to
    : put wet snouts and paws right on the front element. :)
    :
    : BTW, Canon offers "Protection Filters" for exactly that reason ---
    : no need to use UV filters.

    That sounds a bit strange to me. Most glass blocks UV fairly effectively.
    (That's why photochromic sunglasses don't work well inside automobiles.) When
    you want glass that doesn't (e.g., for hospital sunroom windows), only certain
    types of glass will do. I'm no expert on glass, but I'd suppose that a plain
    glass filter would, by default, block UV pretty well. So what's the benefit of
    a UV-passing "protection" filter, if not lower cost?

    Bob
     
    Robert Coe, Nov 6, 2010
    #9
  10. eatmorepies

    eatmorepies Guest

    Interesting article - thanks.

    John
     
    eatmorepies, Nov 6, 2010
    #10
  11. I wrote essentially the same above with, "The greatest differences will show
    on your longest FL lens with the widest stop, shot wide open. I have compared
    (on a 400mm f3.5 Nikkor) no filter, rear filter only, front filter only, and both
    front and rear filters in place (with Nikkor filters, and refocusing as necessary).
    [Using a near infinity-focus full frame width target.] No differences were noted
    with careful viewing."
    The results reported in the URL site given above may just have proven that the
    particular Hoya filter used really was not "top quality"...
    --DR
     
    David Ruether, Nov 6, 2010
    #11
  12. eatmorepies

    Ofnuts Guest

    If your probabilty of damage is above average it's a different matter.
    But you are going to pay dearly for the filter and will have to replace
    it often... TANSTAAFL.
     
    Ofnuts, Nov 6, 2010
    #12
  13. eatmorepies

    Bruce Guest

     
    Bruce, Nov 6, 2010
    #13
  14. eatmorepies

    Bruce Guest


    I do a lot of shooting on construction sites and protective filters
    are essential. But you are quite wrong about having to replace them
    often. The coatings give some protection against abrasion as well as
    against reflections.

    Careful buying means they aren't anywhere near as expensive as a
    casual Google search might suggest, and they also last a lot longer
    than you might think. I have only ever had to replace filters because
    they have been chipped or broken, most often by a piece of flying
    gravel. I like to get close to construction operations and there is
    obviously some risk attached, but it's better to break a relatively
    cheap filter than a lens's very expensive front element.

    After a day's shooting (and sometimes during the day) I remove the
    filters and wash them under running water with a spot of detergent and
    rinse and dry them carefully. Obviously, that is not practicable with
    a lens.
     
    Bruce, Nov 6, 2010
    #14
  15. Including what's used in most lenses, I think. Maybe not
    enough for film in UV rich areas.
    Ask the other direction. What's the use of a UV filter on a
    digital camera, and shouldn't you use a glass that's
    resistent to damage for protection rather than one that is
    tuned for UV blockage?

    -Wolfgang
     
    Wolfgang Weisselberg, Nov 8, 2010
    #15
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