# Homework Help: Galileo Galileis binocular

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1. May 13, 2015

### Kate16

1. The problem statement, all variables and given/known data

2009 it was 400 years ago, Galileo Galilei (1564-1642) for the first time turned his home-built telescope to the sky, and for this reason is celebrated this year the International Year of Astronomy a group of astronomers, optical engineers and teachers developed a Galilean telescope kits that could be purchased via www.galileoscope.org for only \$ 20. Here is a picture of the finished telescope and below is a table with specifications of the binocular optical characteristics:

Objective diameter: 50 mm (2 inches)
Objective focal length: 500 mm (f/10)
Eyepiece focal length: 20 mm
Magnification: 25x (50x with Barlow)
Field of view: 11/2◦ (3/4◦ with Barlow)
Eyepiece eye relief: 16 mm (22 mm with Barlow)
Eyepiece barrel diameter: 11/4 inches (313/4 mm)

(a) As seen in the table, the telescope in its original form (ie without the so-called Barlow lens) actually a Kepler binoculars, ie both the lens and eyepiece are positive lenses. What becomes the normal pledged binocular length, ie, the distance between the lens and eyepiece, in this case?

(b) The so-called Barlow lens that comes with the kit is nothing more than a negative lens with a focal length of -30 mm. By mounting this between the lens and the eyepiece can peep the angular magnification is doubled to 50 times. This occurs by image focal plane of the lens is enlarged to double size (M = +2) and the eyepiece positioned so that the image of the lens image focal plane ports in the object focus of the eyepiece. Draw a schematic view showing in which the distance lens, Barlow lens and the eyepiece is placed in relation to each other. What will the binocular length, ie, the distance between the lens and eyepiece, in this case?

(c) A third way to mount the binoculars is to use Barlow-lens eyepiece instead standardokularet. Binoculars becomes a "real" Galileikikare, where the image is right side up. What will be the normal pledged binocular length, ie, the distance between the lens and eyepiece, in this case?

2. Relevant equations
G=fobj/feyepiece

Gauss's
1/f=1/s+1/s'

M≡-y'/y=-s'/s

3. The attempt at a solution

I have a hard time understanding what is s' and what is s and so on!