Does anyone have experience collimating cassegrains, specifically an 8” f/12 classical cassegrain telescope? With a collimation cap and/or laser collimator?
I find that when aligned with the laser it looks way off when viewed through the cap and am inclined to trust the cap over the laser. Mostly because there is some play when inserting the laser in the focuser. I have roughly checked the laser collimation by rotating it on a table, it seemed OK.
I’ve been using the Orion CC8 Classical Cassegrain manual which I found online.
Thanks,
MartyG
8" f/12 classic cassegrain collimation
Moderators: defalkner, Sureshks, SEmert
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8" f/12 classic cassegrain collimation
Reflectors: Apertura 12" dob, Orion 8" dob, GSO 8" f/12 classical cassegrain
Refractors: Orion 100ED, Astro-Tech AT72, Vixen NA140ssf
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- SEmert
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Re: 8" f/12 classic cassegrain collimation
I would trust the collimation cap or a sight tube/Cheshire more than a laser for this, especially as that is the only method discussed in the manual. You mentioned some play when inserting the laser collimator. that can greatly affect the collimation. Personally, I'd do the collimation cap or sight tube/Cheshire and follow it up with a star collimation.
Steve Emert
MAS Membership Coordinator
12.5" f/4.7 Obsession Clone Homemade Truss Dob, sometimes equipped with Celestron StarSense Explorer app
Celestron C8 SCT OTA on AVX GEQ mount
Astro-Tech AT72 ED Refractor OTA usually on Explore Scientific Twilight 1 mount or tripod with Benro geared head
Celestron 5" SCT OTA on Explore Scientific Twilight 1 Alt-Az Mount, usually equipped with StarSense Explorer app
Orion 150mm Mak OTA and Orion EQ-G computerized mount
MAS Membership Coordinator
12.5" f/4.7 Obsession Clone Homemade Truss Dob, sometimes equipped with Celestron StarSense Explorer app
Celestron C8 SCT OTA on AVX GEQ mount
Astro-Tech AT72 ED Refractor OTA usually on Explore Scientific Twilight 1 mount or tripod with Benro geared head
Celestron 5" SCT OTA on Explore Scientific Twilight 1 Alt-Az Mount, usually equipped with StarSense Explorer app
Orion 150mm Mak OTA and Orion EQ-G computerized mount
- BradNasset
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Re: 8" f/12 classic cassegrain collimation
Trivia tip- I case you might ever think about this - You don't need "Bob's Knobs" for this, as collimation is done so seldom on this scope. Besides they stick out so far you can't use the lens cap cover anymore.
Brad Nasset
ELO, CGO Keyholder
Celestron Edge HD 8 inch, CGEM mount, with HyperStar system
Celestron C8 (Classic 1975 orange-tube), RA drive, equatorial wedge
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ELO, CGO Keyholder
Celestron Edge HD 8 inch, CGEM mount, with HyperStar system
Celestron C8 (Classic 1975 orange-tube), RA drive, equatorial wedge
Celestron 5 inch truss tube Newtonian, “Astronomers Without Borders” scope
3-D Printed 114/900 Reflector- homemade by me
Celestron 15x70 binocs, Homemade parallelogram binocs mount
Meade 10x52 binocs
Vixen 2.1 x 42 Binocs