To: birding aus <>
Subject: scopes
From: brian fleming <>
Date: Wed, 18 Jan 2006 14:24:10 +1100
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
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