One of the recent messages commented that a particular zoom eyepiece was
not very satisfactory.
In the early days of "zoom" camera lenses the correct description was
"variable focal length" and they had to re-focussed after every "zoom".
This was the case with all three telescopes on display at a BA
demonstration day a few years ago - top brands included!
Modern zoom camera lenses are true "zoom" and hold focus. I suspect that
the problen lies in the fact that with telescopes it is only the
eyepiece which is being adjusted, whereas with a camera lens the whole
optical system can be "zoomed".
The Banyule painted snipe some years ago was an expensive bird! (New
80mm scope with 20-60x eyepiece).
Brian Fleming
Ivanhoe Vic
--------------------------------------------
Birding-Aus is on the Web at
www.birding-aus.org
birding-aus.blogspot.com
--------------------------------------------
To unsubscribe from this mailing list, send the message:
'unsubscribe birding-aus' (no quotes, no Subject line)
to
|
