YOU ABSOLUTELY MUST BUY A TELRAD
For a beginner, and I suspect for an experienced astronomer too, a Telrad
or a red dot finder is the easiest finder for pointing your telescope to the area of the
sky you want to view in the telescope.
I have used (struggled with) two different finders quite a lot. One was a tiny Tasco
straw (tee hee, looking through it is like trying to view the heavens through a black
straw) and the other is a real one (a Meade 8x50) which I still use.
The 8x50 (pictured above, bottom-right) gives nice views at a reasonable
magnification, but it's one thing to be looking through the finder and seeing lovely stars
in it, but yet another to know with exact certitude where the heck those stars you're
seeing in the finder are located up in the sky. Just trying to get the object you're
searching for into the view of the finder is no joke when you're a beginner. Then you've
got the whole left versus right versus up and down thing to work out as you traverse your
scope.
Using an 8x50 finder when you swing your scope looking for a new target,
and you look through the finder, the object you are looking for may not be in the finder's
field of view. You can have a devil of a time finding it let alone centering it.
To get an idea of what a Telrad is, imagine a 1 inch square piece of glass
stuck on top of the tube at the front of your scope facing toward the stars. You look
through the glass window at the sky. With both eyes open you will see the whole sky
including the bit you see through the glass.
You don't even have to put your eye up close to it. Just get your eye somewhere (even a
long way back) behind it.
In the centre of the glass window are three illuminated circles. You can vary the
brightness of the illuminated circles by using the knob on the right-hand side.
Here's the great bit: the centre of these red circles is EXACTLY where your scope is
pointed.
By moving your scope to centre an object in the central circle it MUST by definition be
bang in the field of view in the eyepiece when you look. End of story.
I cannot stress to a newbie the EASE with which a Telrad lets you find STUFF. If you plan
on doing a lot of viewing you will save many hours. This is not an exaggeration.
If you don't get a Telrad then you must at least get a red dot finder which is a similar
concept.
The interesting thing about a Telrad is that the target reticle (the red circles) stays on
the target even if you move your head from side to side. It would take another page
to explain how it actually does this, but the physics of the phenomenon is that the light
of the reticle is focused at infinity, so you see the circles centred over the target
regardless. If the circle is centred over the target object then you are on target,
and it will be visible in your scope. If the circle is not centred over the target
then it may not be. That's it.
Again, I cannot recommend the Telrad highly enough. If you have a
medium to large sized telescope (4" and above) You MUST get one. It will save
you so much time and frustration and the cost is small. If you think the Telrad is
too big for your scope then buy yourself a good Red Dot Finder which works using a similar
principle to the Telrad.
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