Bresser Junior 60/700 Mode D'emploi page 17

Which eyepiece is right?
First of all, it is important that you always choose an eyepiece with the highest focal width for the
beginning of your observation. Afterwards, you can gradually move to eyepieces with smaller focal
widths. The focal width is indicated in millimeters, and is written on each eyepiece. In general, the
following is true: The larger the focal width of an eyepiece, the smaller the magnification! There is
a simple formula for calculating the magnification:
Focal width of the telescope tube : Focal width of the eyepiece = magnification
You see: The magnification is also depends on the focal width of the telescope tube. This telescope
contains a telescope tube with focal width of 700 mm. From this formula, we see that if you use an
eyepiece with a focal width of 20 mm, you will get the following magnification:
700 mm / 20 mm = 35 x magnification
To make things simpler, I've put together a table with some magnifications:
Telescope tube Focal width of
focal width eyepiece
700 mm 24 mm
700 mm 20 mm
700 mm 12,5 mm
700 mm 6 mm
700 mm 4 mm
Magnification with 1.5x inverting lens
29x 43,5x
35x 52,5x
56x 84x
116x 174x
175x 262,5x
Use of the moon filter
F
2@
1%
If the image of the moon is too bright for you,
you can screw the green moon filter into the
bottom of the thread of the eyepiece. Then you
can set the eyepiece normally into the zenith
mirror.
The image that you see by looking through the
eyepiece is now greenish. The moon appears
less bright, and so observation is more ple-
asant.
EN
E
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