Re: [Utah-astronomy] Question on focus

On Feb 9, 2005, at 9:38 AM, Joe Bauman wrote:

[...] Also, if anyone has a minute, can you tell me why it's necessary to focus a telescope at all? You would think that, like an old Instamatic camera, everything beyond a few miles out would be at the "infinity" focal point. I know that's not true, but I do not understand why.

Thanks, Joe

This question I can at least partially answer. I wear some pretty strong glasses (4.5 diopters). Sometimes I view through the telescope with glasses removed. The focus adjustment allows me to make this work (well, the astigmatism is still frustrating...). Jim