Testing a new refractor

I hope to get the new meade 127 ED out in the next few days if the sky clears. I am wanting some opinions from more experienced refractor owners as to how to test the scope to see how well it is collimated and how well it performs for color correction, Star test, bright objects, daylight test or what exactly. I am not very experienced with refractors. Any advice would be appreciated.

Hi Floyd. Did you join the group I mentioned to you before about these scopes? There is a wealth of information there.

One thing you can do right away is use a cheshire to see if collimation is way off. You can do this indoors. Put the cap on the telescope and check the reflections that you see using the cheshire. You will see a series of reflections that look like donuts. They should of course stack on top of each other concentrically.

If you have not done so yet I strongly suggest you join the group. These instructions are more detailed there. Also, if you get into the centering of the lens. Be advised about the setscrews for that. Generally there are two screws in each hole. One is a cover. Remove it and there will be another one inserted below it. That one actually does the movement on the lens. If I were you I would check each hole first before attempting to adjust it (if needed at all). I have heard reports of more than two screws in each hole, which could be confusing.

I would remove screws from each hole until you are sure there are no more in that hole. Do it one at a time, then put them back in and move to the next hole. Its better to know before you start, because you might think you are adjusting it when actually it is not the lowest screw. I have also heard of some where there was only one in each hole.

Again though. the group has great files and text isntructions that are very detailed on how to perform any of these steps. Good luck, hope you got a good one.

I would cut to the chase, and suggest testing
on bright white star directly overhead. Use
simple eyepiece design like UO ortho, around
5mm. No diagonal, no Barlow (sorry about
twisted neck) -- just the scope lens
and eyepiece. Let it temperature equilibrate
outdoors for an hour at least, lens capped pointing
straight up.

Look at image at best focus -- see whats there.
Purple halo? How about the Airy pattern --
it is text book -- nice disk and single faint
uniform ring? Or is the ring brighter on
one side (coma)? Two rings (zones)? Or is
the ring brighter in 3 places (pinch) or
four places (astigmatism)?

Move the focus inward so there are about 5
rings visible. Then outside best focus so
5 rings are visible. Are the patterns nice
and round (no astig or pinch)? It the pattern
center-brightened inside focus and
edge-brightened on the other side of focus
(or vice-versa -- spherical)? Is there much
coloration to the patterns? Repeat these with deep
green filter. Make a sketch of what you see,
if there are potential issues.

If there are issues, try to rotate the eyepiece,
just to make sure the problem does not rotate with
the eyepiece. Or try a different eyepiece.

The out-of-focus star test is extremely sensitive.
It may reveal issues of no real importance. So do not
dispair if all is not perfect. Al Nagler would say
"Its the in-focus image that counts."

Theres lots written about all this, but these
tests will get you well on your way to understanding
the lens and issues it may have.

I would suggest the above type of test before doing
any collimation tweaks indoors, etc.
I have seen lenses that badly fail Cheshire
tests, yet give excellent star tests. Sometimes
mechanical mis-collimation is used to
correct optical issues.

Please post results -- these scopes are very
interesting -- potentially excellent value.