View Full Version here: : plastic barlows
robagar
30-05-2006, 11:27 AM
Is it true that some cheap 3x barlows have plastic lenses? :eyepop:I can't believe it, but the person that told me was adamant.
janoskiss
30-05-2006, 01:04 PM
What's wrong with plastic?! Get with the times! Plastic is glass for the 21st century!! cutting edge technology incorporating high performance refractive index in an optimally delineated high density polymer matrix. :P I've got one of those 3x barlows. I never bothered to put it in the focuser. It looks pretty craptacular. I don't know what the lens is but the barrel and housing are all plastic.
asimov
30-05-2006, 01:14 PM
They make good extension tubes! {minus the optimally delineated high density polymer matrix lens of course} :)
My next door neighbour has a 60mm refractor with a plastic objective...what a beauty! :lol:
when useing them as an extention, do you place it before or after the barlow?
always wondered this...
janoskiss
30-05-2006, 04:13 PM
Depends what you need it for, Vingster. If it sits in the focuser before anything else then it just adds extra travel, it's like having an extra long focuser barrel. Between barlow and eyepiece, it increases the magnification of the barlow (typically). Between barlow and camera, it reduces FOV (increases magnification, typically).
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