Re: Stupid question about magnification

On 20 Jan 2006 06:39:27 -0800, "nick" <svla@xxxxxxx> wrote:

>No one uses a telescope for prime focus imaging? That is sure new to
>me.

Well, technically no, since a telescope has no prime focus. But in the
colloquial sense, prime focus imaging is common. And it is precisely in
that configuration that magnification is meaningless, and has led to
multiple instances of confusion in the past. When you are prime focus
imaging (or imaging at other focus planes) all that is useful to
consider is image scale. Otherwise, magnification is useful when we are
talking about telescopes, and both an objective and ocular are present.

As noted elsewhere, there is also magnification associated with viewing
the virtual image produced by the objective alone. If that is what the
OP was inquiring about, you and others have answered his question just
fine.


>I'll tell you what is the use of it, even if it should be obvious for a
>while. It
>is necessary to understand how telescopes work (magnify). Telescope
>optical power (magnification) is a product of optical power
>(magnification)
>of the objective, and optical power (magnification) of the eyepiece.

I've been designing optics for 25 years, and I've never used this
concept to either understand how telescopes work, or to design their
optics. Understand I'm not saying it is untrue, only that it is a poor
way to think about an optical problem.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
.

Relevant Pages

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