7
6. Using the accessories, a bit of math to
understand how all it works.
Using the accessories is easy and fun. To
change magnification simply swap eyepieces.
To get more magnification simply use the
barlow lens. But how does all of this work?
6.1. Power (magnification)
Your telescope has a focal length of 750mm.
This is approximately the distance between
the telescope lens and its focal point (very
similar to the distance between the focus
point of a loupe and the loupe lens). This is a
very important feature that allows to
determine several interesting facts such as
magnification.
The magnification is determined by the
telescopes focal length and the used
eyepiece. You probably noticed that the two
supplied eyepieces are PL25mm and
PL6.5mm. This means that the PL25mm is a
25mm focal length eyepiece, while the
PL6.5mm is a 6.5mm focal length eyepiece.
To determine the magnification just divide the
telescope’s focal length by the eyepiece’s
focal length. Lets give an example for our
telescope and the supplied eyepieces:
Telescope focal length is 750mm
PL25 eyepiece focal length is 25mm
750𝑚𝑚
25𝑚𝑚
= 50 𝑝𝑜𝑤𝑒𝑟
This means that the PL25 eyepiece provides a
50x power (magnification). This seems low,
but try it, you will see a bright image a lot of
good detail.
6.2. Barlow Lens (not included)
The barlow lens is a very interesting device
(not included). It is a negative lens that
multiplies the telescopes focal length. So a 2x
Barlow multiplies the original focal length by
2x, in this case
750𝑚𝑚 𝑥 2 = 1500𝑚𝑚
.
A 3x Barlow lens multiplies it by 3x.
When used with the PL25 eyepiece you get 2x
the power obtained before
50 𝑝𝑜𝑤𝑒𝑟 𝑋 2𝑥 𝐵𝑎𝑟𝑙𝑜𝑤 = 100 𝑝𝑜𝑤𝑒𝑟
6.3. Erecting lens (not included)
The erecting lens gets you an upright image
view with the telescope. It also adds some
power like the barlow lens. The supplied
erecting lens provides an extra 1.5x power.
Here are some examples on how to use the
accessories.
Some possible accessory combinations
Terrestrial
View
Moon
Deep Sky
Jupiter and
Saturn
PL25mm
Yes
Yes
Yes
PL6.5mm
Yes
Power
50x
50x
50x
115x
ATTENTION!
Never look at the Sun through a telescope. Concentrated Sun
light may cause serious eye injury. Children should use only with adult
supervision
For any other questions please feel free to drop a line or visit our website at: http://www.astroshop.de
nimax Gmbh Otto-Lilienthal-Str. 9
D-86899 Landsberg am Lech
