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Thread: diameter of lens

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    Default diameter of lens

    hey guys.. just wondering... wats the deal abt the diameter of lens. i mean, lens with the same focal lens but some are 62 mm some at 67 mm some are 72 mm diamter.. hows the difference?
    i mean the max and min aperture of these lens all the same. pls enlighten.. thks

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    Default Re: diameter of lens

    Originally posted by dehuis
    hey guys.. just wondering... wats the deal abt the diameter of lens. i mean, lens with the same focal lens but some are 62 mm some at 67 mm some are 72 mm diamter.. hows the difference?
    i mean the max and min aperture of these lens all the same. pls enlighten.. thks
    Lens diameters vary depending on the optical, mechanical and cosmetic design of the lens. It's as simple (or as complex) as that.
    Last edited by Ian; 21st March 2003 at 06:21 PM.
    The Ang Moh from Hell
    Professional Photography - many are called, few are chosen!

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    Default

    hmmm... so does it affect the photographs that come out? say for instance, shooting something with 58mm lens and 67 mm lens at the same focal length and aperture( assuming the optics of the lens are the same or is that not possible, ie: different diameter mean different optics so cannot compare.)

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    Default

    Originally posted by dehuis
    hmmm... so does it affect the photographs that come out? say for instance, shooting something with 58mm lens and 67 mm lens at the same focal length and aperture( assuming the optics of the lens are the same or is that not possible, ie: different diameter mean different optics so cannot compare.)
    if u're talking about filter threads, not really if the design is good... some have small thread but causes vignetting or shadowing with ANY filter...
    but too big can cause side lighting to flare (need hood then)
    so as usual it's not which is better but somewhere hit a balance.

    fyi, generally the brighter and/or wider lenses have bigger threads,
    eg the canon 300mm zooms at f/5.6 u can even put a toilet roll in front and it wun show up on the pic..
    "I'm... dreaming... of a wide... angle~
    Just like the ones I used to know~"

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    Default

    Originally posted by dehuis
    hmmm... so does it affect the photographs that come out? say for instance, shooting something with 58mm lens and 67 mm lens at the same focal length and aperture( assuming the optics of the lens are the same or is that not possible, ie: different diameter mean different optics so cannot compare.)
    This will be fun

    Given that all lenses regardless of optical design produce the exact same amout of light on film for a given shutter, aperture and film speed combination then there is no difference in exposure levels.

    However, there are other factors that effect a lenses performance such as manufacturing tolerances, optical design, types of glass used, mechanical tolerances and stability, coefficiants of expansion and so on to consider. Add to the opto-mechanical considerations the optical properties of the lenses being examined, eg: evenness of illumination, chromatic abberations (all types) optical abberations such as coma, pincushioning and barrel distortions, vignetting, the number of aperture blades and colour temperature neutrality and shifts etc and the problem becomes far more complex.

    In the end it is impossible to say which diameter of lens will perform better at a given aperture and focal length without actually taking shots and examining them with a microscope and a loupe on a lightbox. For example a well designed 52mm diameter lens will outperform a poorly designed 67mm lens.
    The Ang Moh from Hell
    Professional Photography - many are called, few are chosen!

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