At 02:50 PM 7/19/2003 +0800, Albert wrote:
>Sorry, slightly OT, but I was wondering, does anybody know the resolving limit
>on plastic lenses?
>
>One of my students went on a trip and just got back; well, the pictures were
>horrible; taken with a P&S camera that had a plastic lens..
>
>She said she was frustrated after seeing my pics as far as clarity and
>resolution. I'm just curious if anybody knows just how big of a difference
>glass vs. plastics is.
>
>I know based on glasses; glass is less than 1/2 as thick.. So I don't know if
>that's linear or exponential, but that should mean that it at least resolves
>2x as well vs. plastic??
Albert:
I'm not aware that there's any resolution limit on plastic lenses that's
terribly different than glass, and the refraction index of plastic would depend
on the type of plastic used. I know that it's much easier to create aspherical
lenses out of plastic than out of glass (because you can just cast plastic more
easily), and even some high-priced and high-quality Big Name lenses have
plastic aspherical elements in them.
My suspicion is that the P&S camera is just cheaply made and of inferior
quality, possibly with plastic lenses with three or fewer elements. If it's a
one- or two-element lens, it's going to have a very difficult time delivering
quality images, regardless of the configuration of the elements. More elements
are typically used to correct more types of image aberrations, which is why a
relatively stable and simple design like the Zuiko 50/1.8 still has several
elements (5 or 6, depending on the design -- the 1.8 went through a number of
formula changes...). Tell her she needs a better camera, and steer her towards
the Holy OM series. ;-)
Garth
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|