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Thread: do glass has better optics than plastic ?

  1. #1
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    Default do glass has better optics than plastic ?

    hi, material engineering experts out there ? i am curious to know, does glass or plastic make better lenses.. ? which one has better optics properties.. ?

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    Default Re: do glass has better optics than plastic ?

    I believe glass lens is costly than plastic lens. But the plastic element(s) maybe needed in some lens design. Its index bias of plastic may can not be achieve using glass element(s).

    Regards,
    Arto.

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    Default Re: do glass has better optics than plastic ?

    me not an engineer but

    glass is more resistant to scratches and clearer than plastic
    i may be wrong please correct if i am

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    Default Re: do glass has better optics than plastic ?

    Glass should be clearer and has less distortion. Plastic can have higher index/ weight ratio though, that's why it's used in specs only. Plastic lenses for photography usage is often found in the lower range portion only.
    Last edited by Splutter; 8th December 2006 at 01:51 PM.
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    Default Re: do glass has better optics than plastic ?

    Just like your specs, glass has higher refraction index than plastic, ie. you need thicker plastic lens to refract the same angle as glass.

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    Default Re: do glass has better optics than plastic ?

    Quote Originally Posted by Splutter View Post
    Glass should be clearer and has less distortion. Plastic can have higher index/ weight ratio though, that's why it's used in specs only. Plastic lenses for photography usage is often found in the lower range portion only.
    no wonder those good lenses very heavy !

  7. #7

    Default Re: do glass has better optics than plastic ?

    Glass. Telescope lenses are made of glass, high quality glass too.

  8. #8

    Default Re: do glass has better optics than plastic ?

    well i aint no technical person...but just from the sound of it...glass sounds better
    hahaha

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    Default Re: do glass has better optics than plastic ?

    Actually diamond would be better, just that it's too damn expensive
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    Default Re: do glass has better optics than plastic ?

    I am very sure:
    - Glass has higher reflective index than plastic (as mentioned above)
    - Glass can be grinded to near-perfection but plastic can only be molded with a tolerance

    I am guessing but not sure:
    - Coating stick to the glass better than plastic?
    - Plastic breakdown faster than glass?

  11. #11

    Default Re: do glass has better optics than plastic ?

    Plastic will degrade eventually, but not for glass.

  12. #12

    Default Re: do glass has better optics than plastic ?

    If I am not wrong, glass is only used in higher end lenses.

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    Default Re: do glass has better optics than plastic ?

    Quote Originally Posted by Astin View Post
    - Glass can be grinded to near-perfection but plastic can only be molded with a tolerance
    so can plastics.

    Quote Originally Posted by Astin View Post
    I am guessing but not sure:
    - Coating stick to the glass better than plastic?
    - Not true, they have slightly different coating processes and if you ask me, coating sticks better to plastics.

    Quote Originally Posted by Astin View Post
    - Plastic breakdown faster than glass?
    - totally no idea about this..
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    Default Re: do glass has better optics than plastic ?

    Quote Originally Posted by Henessy View Post
    If I am not wrong, glass is only used in higher end lenses.
    sure?
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  15. #15

    Default Re: do glass has better optics than plastic ?

    Got this from an optometrist - GLASS is FAR SUPERIOR to polycarbonates (plastics used in lens making).

    The reason why polycarbs are used are for reason of lower cost and faster production.

    In some specialised aplications, polycarbs are 'superior' as they are easier to work with (read: more cost-effective), as in making shatter-proof lenses. The same can be made from glass, but it costs more.

    Same thing in lenses. Plastics are used, especially in complicated lens designs that require aspherical elements. Far cheaper to mould than to grind for mass production, eventhough the purists manufacturers like Leitz may insist on using only glass.

    Optical properties and the different orders of distortion get too complicated for a feeble mind like mine.

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    Default Re: do glass has better optics than plastic ?

    i read from somewhere that medical instruments has very high end glass for their optics... compared to camera lenses.. the quality is many times superior.

  17. #17

    Default Re: do glass has better optics than plastic ?

    Generally, yes, but that's that's because such instruments are very expensive, very well engineered and do not need the marketable economies of scale (I frankly can't tell the difference between a Zeiss and Olympus microscope or endoscope! Even the Jap product is so well built!).

  18. #18

    Default Re: do glass has better optics than plastic ?

    Interesting question that occupied me for the past 2 hours trawling the net for the answer.

    The best part is that I couldn't find conclusive evidence that glass have better optics in the form of direct comparision between then in the form of MTF..etc charts.

    However, there were indication that progress in plastics manufacturing technology it's closing the gap in lens manufacturing even in preceived quality of the resultant image.

    Making quality lens; Closest comparision I can find, it's biased towards plastics tho.
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  19. #19

    Default Re: do glass has better optics than plastic ?

    Quote Originally Posted by Feinwerkbau View Post
    Got this from an optometrist - GLASS is FAR SUPERIOR to polycarbonates (plastics used in lens making).

    The reason why polycarbs are used are for reason of lower cost and faster production.

    In some specialised aplications, polycarbs are 'superior' as they are easier to work with (read: more cost-effective), as in making shatter-proof lenses. The same can be made from glass, but it costs more.

    Same thing in lenses. Plastics are used, especially in complicated lens designs that require aspherical elements. Far cheaper to mould than to grind for mass production, eventhough the purists manufacturers like Leitz may insist on using only glass.

    Optical properties and the different orders of distortion get too complicated for a feeble mind like mine.
    I am sure that the plastic, if any is used in the lenses, would not be polycarbonate but some other specially formulated ones.

  20. #20

    Default Re: do glass has better optics than plastic ?

    Quote Originally Posted by Splutter View Post
    Actually diamond would be better, just that it's too damn expensive
    Index too high. Very high dispersion.

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