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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 three
supplied eyepieces are Plössl 25mm and Plössl
6.5mm. This means that the Plössl 25mm is a
25mm focal length eyepiece, while the Plössl
6.5m 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:
The Telescope focal length is 750mm
Plössl 25 eyepiece focal length is 25 mm
750𝑚𝑚
25𝑚𝑚
= 30 𝑝𝑜𝑤𝑒𝑟
This means that the Plössl 25mm eyepiece
provides a 30x power (magnification). This
seems low, but try it, you will see a bright
image with a lot of detail.
6.2. Barlow Lens
The Barlow lens is a very interesting device. It
is a negative lens that multiplies the
telescope’s 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. Your
telescope is supplied with a 2x Barlow lens.
When used with the PLössl 25mm eyepiece
you get 2x the power obtained before
30 power X 2x Barlow = 60 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.
6.4. Diagonal Mirror (does not apply to
this telescope model)
This diverts the light coming from the
telescope to an angle of 45 or 90 degrees. It is
useful, because it provides a more confortable
position when observing.
Here are some examples on how to use the
accessories.
Some possible accessory combinations
Terrestrial
View
Moon
Deep Sky
Jupiter and
Saturn
Barlow Lens 2x
Yes
PL6.5mm Eyepiece
Yes
PL25mm Eyepiece
Yes
Yes
Power
Not suitable
60x
30x
115x
