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Thread: Normal or SLD Lens for DSLR?

  1. #1
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    Default Normal or SLD Lens for DSLR?

    Hi all,

    Currently I own a F70 with two Sigma lenses. Thinking of upgrading to a DSLR. Just wondering if I could use my old lens on the DSLR. If so what is the difference between a lens meant for DSLR and a normal lens. Will the picture quality degrade between the two lenses? If I will want to invest in a 17-35mm lens now, should I get a normal one or the one with SLD? (there's a huge price difference)

    Below was abstrated from sigma website.
    " Designed to suit the special characteristics of digital cameras
    SLD (Special Low Dispersion) Glass is used for effective compensation of color aberration. Two pieces of molded glass aspherical lens elements offer excellent correction for distortion as well as all types of aberration. It is an ideal lens for Digital SLR Cameras as well as film SLR cameras
    . "

    Does it means that using a normal lens on a DSLR will cause distortion in the pictures? Any one has any pictures taken with a normal lens on a DSLR and one taken using the SLD lens for me to compare?

    Thank you for your time and best regards,
    Linus

  2. #2

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    No it does not cause distortion. However, unless you are buying a full frame DSLR, the crop factor on most DSLR sensors would require lenses of a higher resolution.

    as you may notice in the quote from the sigma webby, SLD glass corrects colour abberation, which does not equal higher resolution. I believe the respective brands have labels for lenses with high resolution;
    Tamron - Di
    Sigma - DG
    Last edited by Stoned; 23rd October 2004 at 08:41 AM.
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  3. #3
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    Hi Stoned,

    Does it means there's no difference if I were to use it on a D70? What do you mean by a full frame DSLR? Which cameras consider as a full frame DSLR?

    Regarding the color abberation, does it means then the color will be different when taken with a normal lens and one designed for DSLR?

    Thanks,
    Linus

  4. #4

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    Full frame DSLRs currently only consist of the 1Ds and the Kodak DCS pro(i think). The sensor(CCD or CMOS) is essentially the same size as a 35mm negative. Most sensors on cheaper DSLRs(D70,300D,20D,D2H) have a crop of about 1.5X-1.6X. This means they are 1.5X to 1.6X smaller than a 35mm negative.
    Essentially higher resolution is required as an image that is 1.5X-1.6X smaller than a 35mm negative is captured by the sensor and "digital-zoomed" to create a full frame 35mm image.
    With regards to colour aberration, i think it means basically that the colours are inaccurately reproduced. (this depends on the lens and also on the sensor, i'va heard rumours that the kodak DCS produces inaccurate colours)
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  6. #6
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    So does it means it's more advisable to upgrade to a lens made for DSLR instead? Since I am thinking of upgrading to a DSLR? Does the lens made for DSLR have any effect on the SLR then?

  7. #7

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    Yes it is advisable to buy lenses with a higher resolution for DSLRs. I doubt it will have any additional effect on film though.

    IMO, don't stinge on the glass, it is the most important piece of equipment in a photographic set up.
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