equatorial mounts and accuracy of setting circles
Posted 16 October 2012 - 08:46 PM
I am now considering going to a German equatorial mount for my 90mm f/11 refractor.
I was eyeing Celestron's CG4 mount mostly for visual observing, maybe some CCD webcam imaging of binary stars and the moon, planets.
I have no view of polaris from my backyard, which is where 90% of my observing will be done. I like the GOTO aspect of my Alt-Az for finding Messier objects.
Will the setting circles bring me close enough to these fuzzies?
How critical is perfect polar alignment?
I have no direct view of polaris from my backyard, where most of my observing will be done.
I appreciate any input. Thanks!
Posted 16 October 2012 - 09:56 PM
Posted 17 October 2012 - 12:52 AM
A 90 f/11 will probably be pushing that mount. I have a 4" f/12 on a CG5 and it's at it's limit for settling down after focusing. If it's a very light tube you might get away with it but it's the length that's a killer.
Which CG-5 do you have? The CG-5 with the 2 inch SS legs ought to handle a 4 inch F/12 refractor reasonably well, the do put C-11s on them. The modern CG-4 with the 1.75 inch SS legs handles a 120mm F/8.3 reasonably well, it ought to handle a 90mm with the same focal length...
As far as using the setting circles to find targets, they are not that accurate but they can get you close.
Posted 17 October 2012 - 05:19 AM
Posted 17 October 2012 - 06:38 AM
Posted 17 October 2012 - 12:15 PM
Is the Orion Skyview Pro eq. mount that much better than the CG4? The price difference is substantial though the specs are somewhat close.
There must be a quality difference between the two. Is that true?
Getting an object within 1-2 FOVs of a low-power eyepiece is perfectly fine. Is that a reasonable expectation with the mount's setting circles?
Posted 17 October 2012 - 12:37 PM