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  1. #1

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    Pentax SMC lenses do not require UV Filters. Any other makes the same?

    I am not one for filters but sometimes think that the haze in some negative images might be reduced by a UV or skylight filter. Pentax SMC lenses, according to the makers, are "opaque to UV radiation". I have just bought a Pentax MX plus 50mm SMC to have a go with but how do other makes fair with UV? The only times I use a filter normally is a skylight for slide film or a yellow filter for black and white. I don't use filters to protect the lens. I also read that modern films are not particularly sensitive to UV.

    Dave

  2. #2
    darinwc's Avatar
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    i am not a lens designer, but the best I can tell, UV filters do nothing for color film. Atmospheric haze is usually visible in the normal spectrum in the form of dust, smog, and mist. I have never seen a "with uv filter/without" example that was not doctored.

    It may be that pentax lenses have a coating that blocks UV light. But I dont think any lens really needs a UV filter unless you are using old-school film that may be oversensitive to UV.
    Go not to the elves for counsel, for they will say both yes and no.

  3. #3
    Roger Cole's Avatar
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    Most glass itself attenuates most UV. I think the only reason to ever use a UV filter is to protect the more expensive lens and then only in certain environments (ocean spray, shooting close ups of long tongued dogs, whatever.)

  4. #4

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    Hello,
    the use of an UV-filter is recommended only: 1) with older lenses with only single or without any coating, 2) with lenses with only 3 or 4 lenses, 3) if you are in high areas above sea level, I think over 3000 mtr. 4) in bright sunshine at sea, 5) to protect the front lens.
    Every filter is a plane-parallel plate, the designer of the lens has not calculated in his design and the image quality (theoretically) will be worse than without filter, especially the sensitivity for flare and reflexes is enhanced, therefore you never should use a filter for night-shots.

  5. #5

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    Thanks for the replies. I'm not sure what they mean by "modern films" and I've never really liked using filters much. Just wondering if I should use them more.
    Dave

  6. #6

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    Hello Dave,
    every photograhic emulsion is very sensitive to UV rays because the energy of light is dependent on the wavelength. The shorter the wavelength the more sensitive. Very short wavelength Gamma rays or X-rays are most dangerous for silver emulsions (and for us too). If you want to eleiminate the blueish haze in the far landscape or in pictures from mountains into the valley, you should try a polarizing filter. This haze comes from light scattered on tiny droplets of water and dust particles in the atmosphere and is partially polarized, the filter can block this. The colour saturation gets much better. I think for your MX you need only a linear polarizing filter, they are quite cheap to get on the used market.

  7. #7

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    I have a polarising filter made by B+W. I have used it for darkening skies and it worked well even though it is single coated. In fact, single coated filters seem fine generally as long as i am not shooting straight into the sun. My Canon FD 50mm f1.8 is only single coated anyway, I believe. On a tripod I often shade the lens with my hand (my rubber shade fell to pieces some time ago. I guess i was just asking the question out of interest as SMC lenses have a good reputation.

    Dave

  8. #8
    Roger Cole's Avatar
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    For filters single coating is fine. Most of the improvement in transmission efficiency and reduction in reflection comes from the first layer of coating anyway. The difference between single and multicoating really only become significant when they are multiplied over multiple lens elements. The more elements, the more improvement multicoating represents.

  9. #9

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    For anyone who is interested the quote, "....opaque to ultra vioet light and this obviates the need for a UV filter" comes from the Pentax commissioned book 'Pentax ME Super book of Photography'. The current Pentax website seems to have downgraded this claim to,"reduce ultra violet". Here is a link to where I read it.

    http://www.pentaximaging.com/camera-...uct-highlights

    Dave



 

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