----- Original Message -----
Sent: Saturday, September 13, 2003 12:52 AM
Subject: [M]: Meade Zero Image-Shift Microfocuser Focus Problem


> Just received my Zero Image-Shift Microfocuser, installed it on my classic
> LX200 and can't get it to focus. The focuser appears to work OK
mechanically
> as I can see the 2" diagonal moving in and out as I adjust the focus at
the
> highest speed (slew speed buttons) by pressing either the up or down arrow
> while holding down the focus key at the same time. I get a very out of
focus
> star (with a perfect diffraction ring by the way) which changes not at all
> while I rack the microfocuser from all the way in to all the way out.
>
> Can anyone provide me with a clue as to what I might be doing wrong?
The key is to realise that the main mirror focusser has a travel of a couple
of inches, but this is optically 'magnified' by the secondary, to give a
final focus travel of perhaps 10"+. The Crayford style focussers only have a
travel of about 1". Hence the key is that you have to be close to the
correct focus position with the main mirror, before the Crayford focusser is
used, or the adjustment range, just will not be enough.
So set the microfocusser to about the middle of it's travel. Now focus with
the main mirror focusser, till you are close to focussed. If you are using a
mirror lock, now tighten this. At this point, the microfocusser now has the
travel needed to get perfect focus.

Best Wishes

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