I need some help and advice here. I recently purchased the older orange tube 8" Celestron. I am enjoying the views but I notice that using high power that some collimating is needed. I collimate my reflectors all the time, so I know how to do that, but how does one go about collimating the Schimdt Cassegrains? My Celestron has the three small allen screws on the outside part of the central mirror holder. I suspect those are the adjusters. I have heard of Bob's Knobs. Are these easy to install? I have all the collimating tools for the reflectors, including the laser beam. Can these tools be used? Thanks for any help or advice. John
Collimating my SCT
Started by scopeking, 07/27/2008 11:20AM
Posted 07/27/2008 11:20AM
Opening Post
Posted 07/27/2008 03:15PM
#1
John
you can find a lot of info about collimating an SCT on the web by just 'googeling' those terms. My personal bottom line is:
- Lasers are not of much help (tried them myself; from you post I assume that your miscollimation is not obvious in the alignment of the shadow of the secondary)
- The Allen screws the scope comes with do the job. My SCTs hold collimation quite well.
- Looking at the diffraction pattern w/o diagonal (just an eyepiece straight through) the mental image I use to 'find the right screw to turn' is shown in the picture.
Hope this helps
Frank
you can find a lot of info about collimating an SCT on the web by just 'googeling' those terms. My personal bottom line is:
- Lasers are not of much help (tried them myself; from you post I assume that your miscollimation is not obvious in the alignment of the shadow of the secondary)
- The Allen screws the scope comes with do the job. My SCTs hold collimation quite well.
- Looking at the diffraction pattern w/o diagonal (just an eyepiece straight through) the mental image I use to 'find the right screw to turn' is shown in the picture.
Hope this helps
Frank
Attached Image:
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