Chris.B

"Jeroen Smaal" <jsnews@REMOVE-THIS.zippy.xs4all.nl> wrote in message news:<3f056579$0$135$e4fe514c@dreader4.news.xs4all .nl>...

>
> When a telescope is focused properly, it projects an image at 'infinity'.
> When the eye is focused at infinity, the eye muscles are in a relaxed state
> (for people that do not need glasses, anyway), meaning there is no strain to
> the focus muscle.
>
> Jeroen.

I'm always surprised when I read this about infinity. When using the
telescope. I can hold an arm out straight (both eyes open as usual)
and Jupiter (or whatever) is sharply focussed & superimposed on my
thumbnail (at any power). There is never any sensation of the image
being more distant than this. I normally wear about one diopter
negative glasses. (Though never at the telescope). Is this the reason
for the closeness of my 'virtual' image in space? Assuming I could
wear my glasses with a long eye relief eyepiece. I could see if the
image removes itself into the distance I suppose.

Chris.B