Bresser 60/700 Mode D'emploi page 20

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 smal-
ler 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 magnifi -
cation! There is a simple formula for calculating the magnifi cation:
Focal width of the telescope tube : Focal width of the eyepiece = magnifi cation
You see: The magnifi cation is also depends on the focal width of the telescope tube. This te-
lescope 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 magnifi cation:
700 mm / 20 mm = 35 x magnifi cation
To make things simpler, I've put together a table with some magnifi cations:
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
20
Magnifi cation with 1.5x inverting lens
29x 43,5x
35x 52,5x
56x 84x
116x 174x
175x 262,5x
Use of the moon fi lter
F
2@
1%
If the image of the moon is too bright for you,
you can screw the green moon fi lter 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 ap-
pears less bright, and so observation is more
pleasant.
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