The importance of a uv filter?

Discussion in 'Digital Photography' started by Duffer, Aug 10, 2004.

  1. Duffer

    Duffer Guest

    OK, I understand the need to protect the lens. But what else? (Yeah, I'm a
    point and shoot kind of guy)
     
    Duffer, Aug 10, 2004
    #1
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  2. Duffer

    Beowulf Guest

    On Mon, 09 Aug 2004 23:21:35 +0000, Duffer wrote:

    > OK, I understand the need to protect the lens. But what else? ..


    What else about what? Do you mean what other purpose does the UV filter
    server?


    --
    "It said it needed Windows98 or better installed, so I installed Linux."
     
    Beowulf, Aug 10, 2004
    #2
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  3. Duffer

    Jeremy Nixon Guest

    Duffer <> wrote:

    > OK, I understand the need to protect the lens. But what else? (Yeah, I'm a
    > point and shoot kind of guy)


    It cuts down the ultraviolet light entering the camera, to prevent it from
    affecting the picture. In practice, digital sensors are far less sensitive
    to UV light than film is, so, not much need. Infrared can be much more of
    an issue than ultraviolet with digital. (Your digital camera has a filter
    built in to block infrared light.)

    --
    Jeremy |
     
    Jeremy Nixon, Aug 10, 2004
    #3
  4. Duffer

    Duffer Guest

    "Jeremy Nixon" <> wrote in message
    news:...
    > Duffer <> wrote:
    >
    >> OK, I understand the need to protect the lens. But what else? (Yeah, I'm
    >> a
    >> point and shoot kind of guy)

    >
    > It cuts down the ultraviolet light entering the camera, to prevent it from
    > affecting the picture. In practice, digital sensors are far less
    > sensitive
    > to UV light than film is, so, not much need. Infrared can be much more of
    > an issue than ultraviolet with digital. (Your digital camera has a filter
    > built in to block infrared light.)
    >
    > --
    > Jeremy |


    Thank you!
     
    Duffer, Aug 10, 2004
    #4
  5. On Mon, 09 Aug 2004 23:21:35 GMT, "Duffer" <>
    wrote:

    >OK, I understand the need to protect the lens. But what else? (Yeah, I'm a
    >point and shoot kind of guy)


    Duffer,

    normally there is no need to protect the lens. Every filter
    degrades your lens performance, mainly through additional
    reflections which reduce contrast and create bright spots in
    night photos.

    Therefore I recommend to use a filter only when you really need
    it.

    Lenses have a hard coating, so wiping of dust or fingerprints
    with suitable materials is no problem.

    Hans-Georg

    --
    No mail, please.
     
    Hans-Georg Michna, Aug 10, 2004
    #5
  6. Duffer

    Crownfield Guest

    Hans-Georg Michna wrote:
    >
    > On Mon, 09 Aug 2004 23:21:35 GMT, "Duffer" <>
    > wrote:
    >
    > >OK, I understand the need to protect the lens. But what else? (Yeah, I'm a
    > >point and shoot kind of guy)

    >
    > Duffer,
    >
    > normally there is no need to protect the lens. Every filter
    > degrades your lens performance, mainly through additional
    > reflections which reduce contrast and create bright spots in
    > night photos.
    >
    > Therefore I recommend to use a filter only when you really need
    > it.
    >
    > Lenses have a hard coating, so wiping of dust or fingerprints
    > with suitable materials is no problem.


    for me, any interchangeable lens:

    if you scratch or chip the filter, it only costs how much?
    new filter, 72mm is about 90.
    any camera store will sell you the replacement (45 min).

    if you scratch or chip the lens, it only costs how much?
    factory service, starts at several hundred dollars.
    many days lost. (2-3 weeks?)
    only factory will touch damaged lens.


    >
    > Hans-Georg
    >
    > --
    > No mail, please.
     
    Crownfield, Aug 10, 2004
    #6
  7. Duffer

    Beowulf Guest

    On Tue, 10 Aug 2004 16:37:33 +0200, Hans-Georg Michna wrote:
    ...
    > normally there is no need to protect the lens. Every filter
    > degrades your lens performance, mainly through additional
    > reflections which reduce contrast and create bright spots in
    > night photos.
    >
    > Therefore I recommend to use a filter only when you really need
    > it.

    ...
    ...

    I disagree -- a lens is expensive and any scratches will show on all
    subsequent photos. A protective filter is cheap and easily replaceable. I
    can not imagine not having a protective skylight or UV filter on each of
    my lenses from the first day I buy them.
     
    Beowulf, Aug 10, 2004
    #7
  8. On Tue, 10 Aug 2004 10:15:22 -0700, Crownfield
    <> wrote:

    >for me, any interchangeable lens:
    >
    >if you scratch or chip the filter, it only costs how much?
    >new filter, 72mm is about 90.
    >any camera store will sell you the replacement (45 min).
    >
    >if you scratch or chip the lens, it only costs how much?
    >factory service, starts at several hundred dollars.
    >many days lost. (2-3 weeks?)
    >only factory will touch damaged lens.


    Crownfield, Beowulf,

    I've taken tens of thousands of photos over many years, but
    never scratched the lens. The main reason is that the lens is
    recessed inside a metal ring, so it's actually not simple to
    scratch it. For example, put the camera on a concrete floor with
    the lens down and the glass of the lens will not actually touch
    the floor.

    So I don't see why should I put a protective filter on the lens,
    particularly if it degrades picture quality.

    I don't know what you do to your cameras and lenses. Perhaps you
    really need a protective filter. In any case, the points have
    been made and everybody can make an informed decision.

    Taking night shots with lights with and without protective
    filter is an eye-opener. Do it.

    Hans-Georg

    --
    No mail, please.
     
    Hans-Georg Michna, Aug 11, 2004
    #8
  9. Duffer

    Bob Salomon Guest

    In article <>,
    Hans-Georg Michna <> wrote:

    > Taking night shots with lights with and without protective
    > filter is an eye-opener. Do it.


    Coated, single coat or true Multi-coated filter?
    Glass or acrylic filter?
    Solid glass or sandwiched construction filter?

    --
    To reply no_ HPMarketing Corp.
     
    Bob Salomon, Aug 11, 2004
    #9
  10. Duffer

    RonFrank Guest

    I have UV filter on all my lenses, and always have.

    As for never scratching a lens, I'm not sure how that is possible if you in
    fact do anything in the way of location photography. I've replaced many UV
    filters over the years, but no lenses due to scratched front elements. I
    take good care of my equipment, but there is zero possibility that when
    shooting a large number of days in a year that a front element will not come
    into contact with something other that air.....

    Just basic cleaning over time is going to destroy the coating on the front
    element.

    Once can always remove the filter in high flare situations. But in general
    UV filters do NOT degrade image quality to any visible degree, and they
    definately protect the front element.

    BTW, not all lenses have recessed front elements, in fact many WA lens have
    protruding front elements. Ironically those R the ones most in need of
    protection, and some (like he Sigma 14mm) can not take front filters.

    Ron


    "Hans-Georg Michna" <> wrote in message
    news:...
    > On Tue, 10 Aug 2004 10:15:22 -0700, Crownfield
    > <> wrote:
    >
    > >for me, any interchangeable lens:
    > >
    > >if you scratch or chip the filter, it only costs how much?
    > >new filter, 72mm is about 90.
    > >any camera store will sell you the replacement (45 min).
    > >
    > >if you scratch or chip the lens, it only costs how much?
    > >factory service, starts at several hundred dollars.
    > >many days lost. (2-3 weeks?)
    > >only factory will touch damaged lens.

    >
    > Crownfield, Beowulf,
    >
    > I've taken tens of thousands of photos over many years, but
    > never scratched the lens. The main reason is that the lens is
    > recessed inside a metal ring, so it's actually not simple to
    > scratch it. For example, put the camera on a concrete floor with
    > the lens down and the glass of the lens will not actually touch
    > the floor.
    >
    > So I don't see why should I put a protective filter on the lens,
    > particularly if it degrades picture quality.
    >
    > I don't know what you do to your cameras and lenses. Perhaps you
    > really need a protective filter. In any case, the points have
    > been made and everybody can make an informed decision.
    >
    > Taking night shots with lights with and without protective
    > filter is an eye-opener. Do it.
    >
    > Hans-Georg
    >
    > --
    > No mail, please.
     
    RonFrank, Aug 11, 2004
    #10
  11. Duffer

    Guest

    "RonFrank" <> wrote:

    > Just basic cleaning over time is going to destroy the coating on the front
    > element.


    Camera equipment is expensive. But it is so expensive that one must
    speak foolishness?
     
    , Aug 11, 2004
    #11
  12. On Wed, 11 Aug 2004 09:49:04 -0400, Bob Salomon
    <> wrote:

    >In article <>,
    > Hans-Georg Michna <> wrote:


    >> Taking night shots with lights with and without protective
    >> filter is an eye-opener. Do it.


    >Coated, single coat or true Multi-coated filter?
    >Glass or acrylic filter?
    >Solid glass or sandwiched construction filter?


    Bob,

    no matter, in night shots you always see the additional light
    spots. No filter is free of reflections.

    I usually use multi-coated solid glass filters.

    Hans-Georg

    --
    No mail, please.
     
    Hans-Georg Michna, Aug 12, 2004
    #12
  13. On Wed, 11 Aug 2004 09:25:39 -0600, "RonFrank"
    <> wrote:

    >I have UV filter on all my lenses, and always have.


    Ron,

    let's ask this question: How far does the extra UV filter reduce
    the contrast?

    Hans-Georg

    --
    No mail, please.
     
    Hans-Georg Michna, Aug 12, 2004
    #13
  14. "Hans-Georg Michna" <> wrote in
    message news:...
    > On Wed, 11 Aug 2004 09:25:39 -0600, "RonFrank"
    > <> wrote:
    >
    > >I have UV filter on all my lenses, and always have.

    >
    > Ron,
    >
    > let's ask this question: How far does the extra UV filter reduce
    > the contrast?


    At least 3% for two glass/air surfaces, which is a lot if you add 3%
    of a bright area to a dark area!
    Theoretically it could add some RGB 8,8,8 to the linear gamma shadows,
    on its own, before the lens groups come into play, and before gamma
    adjustment boosts it further.

    Bart
     
    Bart van der Wolf, Aug 12, 2004
    #14
  15. On Thu, 12 Aug 2004 14:26:16 +0200, "Bart van der Wolf"
    <> wrote:

    >"Hans-Georg Michna" <> wrote in
    >message news:...


    >> On Wed, 11 Aug 2004 09:25:39 -0600, "RonFrank"
    >> <> wrote:


    >> >I have UV filter on all my lenses, and always have.


    >> let's ask this question: How far does the extra UV filter reduce
    >> the contrast?


    >At least 3% for two glass/air surfaces, which is a lot if you add 3%
    >of a bright area to a dark area!
    >Theoretically it could add some RGB 8,8,8 to the linear gamma shadows,
    >on its own, before the lens groups come into play, and before gamma
    >adjustment boosts it further.


    Bart,

    thanks for the quantification. I suspected something like this.

    In other words, you don't want any superfluous filters, at least
    when you take high-contrast photos. Night shots are just an
    extreme example and make the extra reflections very visible.

    Hans-Georg

    --
    No mail, please.
     
    Hans-Georg Michna, Aug 12, 2004
    #15
  16. "Bart van der Wolf" <> writes:


    >At least 3% for two glass/air surfaces, which is a lot if you add 3%
    >of a bright area to a dark area!


    It depends a lot on the filter coatings. If I remember correctly,
    uncoated glass or plastic with a refractive index around 1.5 reflects
    about 4% per surface. But a single-layer coating brings that down
    dramatically, and good multi-layer coatings are in the 0.5-1% range per
    surface.

    Dave
     
    Dave Martindale, Aug 13, 2004
    #16
  17. "Dave Martindale" <> wrote in message
    news:cfgtja$755$...
    > "Bart van der Wolf" <> writes:
    >
    >
    > >At least 3% for two glass/air surfaces, which is a lot if you add

    3%
    > >of a bright area to a dark area!

    >
    > It depends a lot on the filter coatings. If I remember correctly,
    > uncoated glass or plastic with a refractive index around 1.5
    > reflects about 4% per surface.


    Per surface, yes that's what I recall as well.

    > But a single-layer coating brings that down dramatically, and
    > good multi-layer coatings are in the 0.5-1% range per surface.


    Correct, a *good* multi(!)-layer coated UV filter will reduce the loss
    of contrast, assuming a good lens hood is used to keep false light
    away from the protruding filter :-(
    The multi-coating is also not extremely resistant to 'environmental'
    influences, although they have improved over the years. Some are hard
    to clean without leaving smudges, but clean micro-fiber cloth will
    achieve it.

    Bart
     
    Bart van der Wolf, Aug 13, 2004
    #17
  18. "Dave Martindale" <> wrote in message
    news:cfgtja$755$...
    SNIP
    > If I remember correctly, uncoated glass or plastic with a
    > refractive index around 1.5 reflects about 4% per surface.


    In fact the formula for normal (!) incidence is (with n as refractive
    index):
    R=((n-1)/(n+1))^2, per air to glass surface, so it is exactly 4%.

    At larger angles of incidence the reflection increases up to total
    reflection, and the efficiency of AR coatings decreases with deviation
    of the lightpath from the quarter wavelength thickness.

    Bart
     
    Bart van der Wolf, Aug 13, 2004
    #18
  19. "Bart van der Wolf" <> writes:

    >The multi-coating is also not extremely resistant to 'environmental'
    >influences, although they have improved over the years. Some are hard
    >to clean without leaving smudges, but clean micro-fiber cloth will
    >achieve it.


    Have you ever scratched a lens surface doing this? I'm always leery of
    the possibility of a tiny bit of grit in the cloth causing noticeable
    damage if I rub the lens using any significant pressure.

    I've always gotten good results using liquid cleaning, which takes very
    little pressure. I normally start with a detergent-based lens cleaner
    like Kodak lens cleaner, applying it with a new cotton Q-tip. Then wipe
    off (using little pressure) with some sort of absorbent cloth. If the
    cleaning solution evaporates and dries before you get it soaked up by
    the cloth, there will be some detergent residue left on the lens, but it
    comes off nicely in a second pass using distilled water.

    Occasionally, I'll see gunk on a lens that isn't water-soluble, and the
    Kodak cleaner won't touch it. Then I experiment with pure isopropyl
    alcohol and/or petroleum naphtha based lighter fluid. Both of these
    evaporate with no residue from a clean surface, and they're not too
    agressive so they're unlikely to damage plastic or paint if contact is
    limited to a few seconds.

    Dave
     
    Dave Martindale, Aug 14, 2004
    #19
  20. "Dave Martindale" <> wrote in message
    news:cfk2i0$sml$...
    > "Bart van der Wolf" <> writes:
    >
    > >The multi-coating is also not extremely resistant to

    'environmental'
    > >influences, although they have improved over the years. Some are

    hard
    > >to clean without leaving smudges, but clean micro-fiber cloth will
    > >achieve it.

    >
    > Have you ever scratched a lens surface doing this?


    Not yet.

    > I'm always leery of the possibility of a tiny bit of grit in
    > the cloth causing noticeable damage if I rub the lens using
    > any significant pressure.


    Yes, grit and grease require a different approach. My common
    procedure, which is rarely needed, is to use a (blower) brush to
    remove loose surface grit/lint, vigorously shake the *clean*
    microfiber cloth (optical grade) to unfold, breath on the surface of
    the lens/filter, and wipe gently in a motion that rotates the cloth
    from the surface as I move forward. Usually the (blower) brush is
    sufficient, unless an accidental fingerprint finds it way to the
    surface. In extreme cases one could consider lens cleaner on the
    cloth.

    Bart
     
    Bart van der Wolf, Aug 14, 2004
    #20
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