Collimating a Bird Jones

[baggywrinkle]

I picked up the 76mm in the attached photo at a car boot sale for 8 Quid.

It appears to be a hydride, it has a collector plate, main mirror and a secondary mirror. Inside the focuser is another lens.

The main mirror is not adjustable at all. However there are 3 screws for allowing the setting of the secondary.

I checked the OTA on the moon this morning and it definitely needs collimating. Has anyone on SGL ever collimated one of these and can they offer any advice.?

[Steve Ward]

Found an old thread on CN about it but nothing concrete regarding collimation unfortunately ... 

http://www.cloudynights.com/topic/60633-unusual-cat/#entry782565

[baggywrinkle]

/\ Thanks...

[Peter Drew]

You should be able to collimate it via the three secondary adjustment screws and the usual Newtonian collimation tools.

[Brave Sir Robin]

If it is a bird-jones you will need to remove the lens in the focus tube before collimating. Make sure you note which way it came out, and put it back the same way after your adjustments.

The Celestron Astromaster 114 is similar in this respect, but they don't tell you that in the instructions!

Good Luck!