do glass has better optics than plastic ?


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raincool2005

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Sep 10, 2005
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#1
hi, material engineering experts out there ? i am curious to know, does glass or plastic make better lenses.. ? which one has better optics properties.. ? :think:
 

Artosoft

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Aug 31, 2005
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#2
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.
 

ortega

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Nov 2, 2004
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#3
me not an engineer but

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

Splutter

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#4
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.
 

arpinkor

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May 13, 2005
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#5
Just like your specs, glass has higher refraction index than plastic, ie. you need thicker plastic lens to refract the same angle as glass.
 

raincool2005

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#6
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 !:bsmilie:
 

Apr 19, 2006
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#7
Glass. Telescope lenses are made of glass, high quality glass too.
 

Witness

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#8
well i aint no technical person...but just from the sound of it...glass sounds better
hahaha
 

Astin

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#10
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?
 

yanyewkay

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Sep 22, 2004
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#13
- Glass can be grinded to near-perfection but plastic can only be molded with a tolerance
so can plastics. ;)

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.

- Plastic breakdown faster than glass?
- totally no idea about this..
 

Feinwerkbau

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#15
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. :bsmilie:
 

raincool2005

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#16
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. :sweat:
 

Feinwerkbau

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#17
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!).
 

CYRN

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Nov 14, 2002
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#18
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.
 

lsisaxon

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Nov 29, 2004
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#19
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. :bsmilie:
I am sure that the plastic, if any is used in the lenses, would not be polycarbonate but some other specially formulated ones.
 

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