Dual axis equatorial platform

[Stump]

Can someone please explain to me what the point of a dual axis equatorial platform is/ what is the difference to ,for example, the platform in the link http://astroshake.com/2012/10/diy-equatorial-platform-in-pictures/

[AstroJunk]

To some extent they are all dual axis in that you can adjust the N/S axis to account for latitude a little.

A true dual axis platform allows more sophisticated adjustment in the north/south axis as the platform is tracking to ensure that the image is dead centre. This is often done by way of an autoguider set-up and associated with large aperture instruments mainly because of the relative costs involved in the electronics.

[Stump]

Thanks for the response Jonathan.

But if you had a perfectly made platform and it was perfectly polar aligned it wouldn't be necessary right?

P.S what is your profile pic?

[AstroJunk]

Ah, where is this perfect world you talk of ;)

Its only an issue for longer exposure astrophotography and even then when you are planning many exposures over a long period. The vast majority of platforms are the single axis variety and used perfectly adequately for visual and some photographic work.

The profile image is of an asteroid passing in front of a star and 'blinking' it out - something that I spend way too much time watching, or not, as they are exceedingly rare events: Explained by me here: http://youtu.be/G8rBBK5Zm-Q