Collimating and testing a CDK-20

[Gama]

Well, with 40 - 45 deg C temperatures for the last few days in Melbourne, the nights have been very hot.
Only last night did the temp's drop a little and bring some cool relief. I used the opportunity to check collimation on the 20" CDK.
Followed the instructions that was supplied by Planewave, and looked very easy indeed.
But reading the spacing of the mirrors needs to be within +/- 1mm made me panic a little.
Then i remembered playing around with one some time back and the panic quickly vanished.
This telescope is one of the most easiest to collimate that i have ever seen. Its as easy as a Newtonian collimation.
Planewave supplies the adapter, spacer and Ronchi eyepiece (Used for checking correct mirror spacing). Use of a normal eyepiece (For centering the secondary shadow) is also required to calibrate the scope. Just slide the adapter and spacer inside the 3.5" focuser and then slide the ronchi or normal eyepiece in. Now your ready to collimate.
Then its just a matter of moving the secondary mirror back and forth using the 3 adjusters (Like on the secondary of a Newtonian). The secondary mirror is spring loaded so adjustment is dead easy.
Just centre the secondary mirror shadow in a out of focus star in a medium power eyepiece by adjusting the 3 screws on the secondary, then swap out the eyepiece with the ronchi to double check you didnt move too far from the required mirror spacing, and finito.
Took me 5 minutes to collimate the scope on my own.
The star test looked pretty good considering the heat waves distorting everything, beautiful tight stars, no flaring, no coma, no nothing.
I was very impressed with just how simple and easy collimation was.
I have to thank Planewave for their thought into putting together the correct tools needed and very simple instruction as to complete what may look to be an impossible job for amauters.

I do so much recommend anyone thinking about investing serious money, to look into this design. You will never regret it.

Theo

[renormalised]

You need an air conditioner in the dome, Theo, for days like this!!!.

[KenGee]

Theo, have you tried CCDware's CCDinspector? it will give you a very good idea just how well you have aligned everything. As you know all mirrors and lenses have to be in the right spot of it all to work. I have found the Tak scope to be the bees kness and I'm able to get to within a few arc seconds of colimination with it. It will also give you a indication on how flat you field is to help find you best focus.

Renormalised I have a air con in my Obs and sometimes it's the coolest place in my house, I've used it as a cool retreat when gardening on a very hot day.

[Gama]

Once the temp's drop far enough to allow decent views, i'll try it.
But the CDK's are not as temperamental as other scopes, and you can still be off a little and still get no errors.

Theo