Re: Field of View and Magnfication calculations
- From: wsnell01@xxxxxxxxxxx
- Date: Thu, 16 Apr 2009 16:40:15 -0700 (PDT)
On Apr 16, 6:45 pm, Eugene <eugenhug...@xxxxxxxxx> wrote:
Hello,
I'd like to know some calculations.
I looked at a ruler at a distance with a telescope
and a 15mm Televue Plossl with 50 degrees field
of view. Here's the figure.
Distance to ruler from objective lens: 5.7 meters.
Ruler distance seen from edge to edge of eyepiece: 75mm
From this. Can one figure out the magnification without
giving the focal length of the telescope given only
the 15mm TV Plossl (50 degrees)?
Also I'm calculating the field of view seen. I used
the formula:
tan theta = y / x = 75mm/5.7meters
theta or degrees = arctan y/x = 0.75
why 0.75 degrees and not 50 degrees??
Tnx!
E
Magnification = 50 / 0.75 = 66.7, approximately
Image distance = 15mm x 66.7 = 1000mm, approximately
Focal Length of Objective = 1/ ( 1/5700 + 1/1000) = 850mm,
approximately
?
.
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