Dual Axis Equatorial Platform

Hi,

I'm interested in building a dual axis equatorial platform for astro-imaging but I'm not sure what is involved. I believe I understand the theory behind a single axis aligned with the north star and right ascension drive. Why is a single drive not enough? I'm relatively new to astronomy and entirely new to tracking.

Thanks in advance,

Andy

A dual axis platform is for photography, so you can plug in an autoguider to correct for any minor errors in polar alignment, bumps on the curved surfaces, etc. Usually the second axis only has a small amount of travel, and is only used for high-power centering and photo guiding. For visual use, a single-axis platform works fine.

Jarad

If you could actually perfectly align your telescope, a second axis may not be necessary. Try it if you already have an equatorial mount. If you like your results, then save yourself the trouble.

Fact is, though, that it is nearly impossible to get everything lined up (polar alignment) just perfectly. ANd the second axis can compensate for some of the error. It may also help if things shift ever so slightly during exposure (depending on your guiding setup).

And it also depends on what you camera and exposure times are. If you are webcamming, or putting together lots of digital shots, you don't have to worry about guiding so much. If you are into emulsion, it will be more critical.

Alex