Do I need a thin polarizer for a Minolta 17-35mm lens?

Discussion in 'Minolta' started by David Farber, Nov 15, 2005.

  1. David Farber

    David Farber Guest

    I'm thinking of buying a Minolta 17-35mm f/2.8-4 (77mm filter) wide angle
    zoom lens for my Maxxum 7. I've already had vignetting problems using a
    standard circular polarizer with my Minolta 24-105mm zoom and would like to
    avoid this problem.

    Thanks for your reply.
     
    David Farber, Nov 15, 2005
    #1
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  2. With such a wide lens a polarizer is of little use.
     
    uraniumcommittee, Nov 15, 2005
    #2
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  3. David Farber

    Paul Furman Guest

    Why?

     
    Paul Furman, Nov 15, 2005
    #3
  4. David Farber

    Matt Clara Guest



    Without going into great detail, you can only tune the polarizer to work on
    light coming at you from certain directions at a time. With a long
    telephoto lens the angle of view is narrow, thus the whole frame can be
    filled with light coming essentially from the same direction, but with a
    wide angle, the angle of view is much greater, and as you rotate your
    polarizer some parts of the image will be effected much more than others,
    some not at all.
     
    Matt Clara, Nov 15, 2005
    #4
  5. The coverage angle is wider than is desirable. Polarization occurs in
    the sky over a small angle at a time. The 'polarizer' that fits over
    your lens is not a 'polarizer' at all, but an analyzer. The
    polarization occurs in the atmosphere, but only over a limited angle.
     
    uraniumcommittee, Nov 15, 2005
    #5
  6. David Farber

    David Farber Guest

    So I guess you're saying that a polarizing filter affects only a narrow
    angle of reflected light and therefore a wide angle lens is not a good match
    for it. Makes sense to me. I can save my money for something else now.

    Thanks for your reply.
     
    David Farber, Nov 16, 2005
    #6
  7. David Farber

    David Farber Guest

    Can you please elaborate about the analyzer part?
     
    David Farber, Nov 16, 2005
    #7
  8. David Farber

    Alan Browne Guest

    While Matt is correct, it can still be used. But care is needed to
    avoid really dark areas in one part of the frame and quite light in the
    other. I *do* use a circ pol with a 20mm lens, but I'm careful about
    where the light is coming from.

    Rule of thumb: Make a pistol with your fingers, thumb up. (90°).
    Point finger at subject. (Pretty big at 20mm!)
    If you can rotate your wrist so that the thumb points at the sun
    (while finger points at subject), then you will get maximum
    polarization. (eg: light source 90° to lens axis is maximum).

    Now imaging the diminishing polarization effect on the rest of the image.

    Then, consider reorienting (and shoot at a different time of day) such
    that the max pol occurs in the sky and not on subject, foreground ...

    Takes some wierd thinking ... but can work well. Of course at 35mm it
    will be less difficult than at 17mm.

    If you shoot slide film, then it will be most difficult to get a
    pleasing result.

    If you get a Max 7D (one day) then the angle of view is narrower so
    you'll be less impacted in any case.

    In closing, at smaller apertures you are at less risk of vignetting than
    at larger apertures. If you can find a thinner pol than the Minolta one
    (mine, anyway, is quite thick and I do vignette on my FFL 20mm at large
    apertures) then get the thinner ones.

    Have fun.

    Cheers,
    Alan
     
    Alan Browne, Nov 16, 2005
    #8
  9. David Farber

    Jerry L Guest

    A polarizer filter 'works' best at 28mm and narrower lenses (35mm,
    50mm, 85mm, etc.)

    A un-even sky effect will be what you will end up with if you use a
    polarizer filter on a 17mm lens, so the 'corners' that are a bit darker
    with a regular polarizer filter will not matter much __ nor will your
    image be improved by getting a thin filter.
    = = =
     
    Jerry L, Nov 16, 2005
    #9
  10. David Farber

    David Farber Guest

    Good trick to know!
    I found a tutorial at
    http://www.luminous-landscape.com/tutorials/polarizers.shtml

    It says, "If the lens is wider than about 24mm, when used at small apertures
    the edge of the ring can cause vignetting at the corners of the frame."

    So do they mean small aperture numbers or small lens openings?
    Thanks for your reply.
     
    David Farber, Nov 16, 2005
    #10
  11. David Farber

    Matt Clara Guest

    I've used polarizers on wide angle lenses to remove reflections in water
    while still capturing land and sky. Nothing wider than 35mm, though.
     
    Matt Clara, Nov 16, 2005
    #11
  12. David Farber

    Paul Mitchum Guest

    If you're describing the aperture as small, then the opening is small,
    since 'aperture' is another word for 'opening.'

    And if the opening is smaller, it has larger numbers (11, 16, 22 ...)
    which are actually smaller numbers (f/11, f/16, f/22 ...). Photography
    isn't complicated at all. :)
     
    Paul Mitchum, Nov 16, 2005
    #12
  13. David Farber

    David Farber Guest

    The reason I mentioned it was because Alan said that with small apertures
    you are at less at risk for vignetting, whereas the above mentioned website
    says the opposite is true.

    Thanks for your reply.
     
    David Farber, Nov 16, 2005
    #13
  14. David Farber

    Jim Guest

    Do you need a polarizer? Only if you want one.

    Should you get a thin one if you want one. Most certainly. I have
    never seen a normal thickness polarizer work on anything less than a
    50mm lens and I have never seen any "thick" filter work on any lnes at
    28 or less. All will cause some vignetting.
     
    Jim, Nov 16, 2005
    #14
  15. David Farber

    Skip M Guest

    Geez, I think the earth just trembled. I was about to post something that
    agreed with UC. A sure sign of the coming apocalypse...

    --
    Skip Middleton
    http://www.shadowcatcherimagery.com
     
    Skip M, Nov 16, 2005
    #15
  16. David Farber

    columbotrek Guest

    In lieu of a thin filter, you could try a step ring. 77mm to say 82 and
    use a 82mm filter. Some filters for wide angle lenses are built with a
    similar feature.
     
    columbotrek, Nov 16, 2005
    #16
  17. David Farber

    David Farber Guest

     
    David Farber, Nov 16, 2005
    #17
  18. David Farber

    David Farber Guest

    Now that's getting creative. I never would have thought have that.

    Thanks for your reply.
     
    David Farber, Nov 16, 2005
    #18
  19. David Farber

    Skip M Guest

    Skip M, Nov 16, 2005
    #19
  20. David Farber

    Matt Clara Guest

    The more you stop down your lens (bigger number, smaller opening) the less
    chance there is of vignetting--that's because you're only using the glass in
    the center of the optical elements to collect the image recorded on the
    film.
     
    Matt Clara, Nov 16, 2005
    #20
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