[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: [ATM] Another Astigmatism question, but at the sphere stage
Hi Jay,
>My question is whether it's too early to judge astigmatism,
>since I'm only at the sphere stage,
Isn't it better to find and fix it now? You can use a pinhole and an eyepiece to do a star test from the radius of curvature, and there won't be any spherical aberration to contend with. You should be able to detect a tiny astigmatism in the image from the separation of the source and eyepiece, but it will not rotate with the mirror.
Of course, you can replace the eyepiece with a spot for a different view. It's the 2D version of the Foucault, and it does see astigmatism.
>Where is everybody?
I was out observing till 4am. :)
John
johnspics.com/a
_______________________________________________
ATM mailing list http://www.atmlist.net/