ETX & DS TECHNICAL TIPS Last updated: 22 July 2005

Subject:	ETX Green Laser Pointer
Sent:	Wednesday, July 20, 2005 17:32:06
From:	Ray Schmidt (rayschmidt@ozemail.com.au)
I have been told many times that the main drawback of GoTo Scopes is
that you do not learn the sky.

Well, my solution to that was to mount a 20mW (for darker sites 5mW
would be more than adequate) green laser pointer under the scope, and
after the ETX has found the object of interest, I briefly flick the
laser on so I can see exactly where it's pointing in relation to other
stars and constellations.

Note that the laser can also be used for sighting on an object without
having to use the finder-scope.

The following points are worth noting for anyone wishing to do something
similar:

1. The pointer needs to have an end-mounted push-on/push-off switch for
accessability, and to avoid wobbling the scope.  Alternatively, the
switch could be mounted on flying leads for remote control.

2. Fixed nylon screws were used at the front and two adjusters at the
rear for lining up with the optical axis. The mounting rings were
scavenged from the original laser mount as supplied, although they could
easily be made from rings cut from a length of aluminium tubing.

3. The third adjusting screw has been removed and replaced with a coil
spring which holds the laser in suspension against the other two
adjusters, because of limited space under the OTA.

4. The positioning of the laser is quite critical to enable easy access,
without hitting on the base as the OTA elevates.

5. CAUTION: Lasers used carelessly can be dangerous.  This is not
recommended for use around crowds of people, for example in public
displays or large star parties.

Ray Schmidt
Australia

In position ready for use.





Looking from underneath





The mount





Close-up of tension spring





Slung under the OTA





The laser in place





The mount in place without the laser





Regards
Ray

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