Why are Equatorial mounts better for AP

Started Nov 22, 2012 | Questions thread
JimP Forum Member • Posts: 98
Re: Why are Equatorial mounts better for AP

If you were just interested in visual astronomy (the old eye up against an eyepiece), then the Alt/Az mount is very convenient.  Simple to align new scopes with electronics.. just set it up, turn it on, aim at 2 stars and you are tracking the sky.  Your scope will find and follow Jupiter all night long.  Even though the field around Jupiter is EVER SO SLOWLY rotating, you won't notice and it doesn't matter.  You can even do short exposure photography (under 30 second exposures) with negligible field rotation.  Also, in Alt/Az mode, the eyepiece is always in a convenient location for viewing.

If you are serious about long exposure astrophotography, then, like the previous fine gentlemen noted, you'll need to switch to equatorial mount (or use a wedge on an Alt/Az mount). Then you can track for LOOOOONG periods of time and the entire field stays nicely aligned.

The downside of an Equatorial mount is that you have to closely align the mount to the polar axis and do an electronic alignment.  Adds some tedium and time, although newer scopes have electronic assist for polar alignment as well (e.g. Celestron's All Star Polar Alignment).  Also, the eyepiece can get into locations where a visit to a chiropractor is required the following day.

Clear skies,


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