Re: Stupid question about magnification

On 19 Jan 2006 20:25:56 -0800, "nick" <svla@xxxxxxx> wrote:

>It's easy: it is given by the apparent size of image it creates
>observed from
>the least distance of distinct vision vs. apparent size of the object.
>That makes
>it (h/d)/(h/f)=f/d, "h" being the image hight, "f" the objective f.l.
>and "d" the least
>distance of distinct vision. With the latter being conventionaly
>accepted as 250mm,
>magnification given by 2700mm is 2700/250=10.8 for an average observer.
>
>Note that this stands only for relatively distant objects. The general
>apparent
>magnification formula is M=of/(o-f)d, "o" being the object distance.

Precisely what I said earlier: there are definitions of magnification
that can be applied to single lenses that are of some interest to
optical designers, but are otherwise useless. This is exactly that.
Nobody would or could make any use of this "10.8" value for a 2700mm
objective.

The correct answer remains the same for the OP: there is no such thing
as magnification with only an objective. The term is only meaningful in
a practical sense with a telescope.

_________________________________________________

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

Relevant Pages

  • Re: Jeckyl wrote
    ... The change is from the viewpoint of the non-local observer. ... closure by the exterior observer would be a distance of 80 yards ... motion, ... Relativity does not demand length contraction. ...
    (sci.physics.relativity)
  • Re: Jeckyl wrote
    ... of that...from the viewpoint of the non-local observer viewing the ... closure by the exterior observer would be a distance of 80 yards ... So there is a length contraction in the transverse direction? ... motion, ...
    (sci.physics.relativity)
  • Re: Jeckyl wrote
    ... of that...from the viewpoint of the non-local observer viewing the ... closure by the exterior observer would be a distance of 80 yards ... So there is a length contraction in the transverse direction? ... motion, ...
    (sci.physics.relativity)
  • Re: Aether is the empty space in which the Universe sits
    ... 'Relativity' that Special and General Relativity are only valid ... SR illustrations always show a universe expanding with every change in the ... Using source and observer rather two sources in order to obtain less ... observer traveled fast enough across that distance, ...
    (sci.physics.relativity)
  • Re: the black fishing hole
    ... Since the weight is lowered slowly, we can model it as a quasistatic observer which is simply closer to the hole (at least until the string breaks!). ... Well, the string will break at some point before the weight reaches the horizon, because the tension in the string diverges, because of the fact about acceleration required for a bit of matter to hover outside the hole as noted above. ... This is the "pedometer distance", since it gives the distance which would be reported by an ant equipped with a pedometer who crawls along the string from the observer to the dangling weight. ...
    (sci.physics.research)