Your ETX is not user collimatable, and does not
normally need it. The Nexstar is collimatable and
will require checking reasonably often for optimum
views. It may well be that collimation is off
slightly.

Adam

--
Eschew obfuscation. Eliminate such idiom previous
to rejoining.
"Chris.B" wrote in message

om...
"Mike Cutts" wrote in
message ...
Dear All,

I've just picked up a 2nd hand Nexstar 8i and
want to compare the
optics/image quality with that of my ETX90 as
quickly as possible. With the
cloudy weather I've resorted to terrestrial
viewing but immediately noticed
that the ETX90 produced a sharper picture. I'm
not sure I approached the


Since nobody ese is having a go at this one: At
the very least you
should attempt to match the magnification
between the two instruments.
You have nearly a 2-1 ratio between the powers.
Don't expect anything at all from looking
through a window. With the
window closed you are at the mercy of (possibly
two layers) of mass
procuced glass between you and the object being
viewed. With the
window open the indoor heat floods out through
the open gap killing
the view stone dead.

Chris.B