7
The magnification provided by the 10mm eyepiece is:
The maximum attainable magnification for a telescope is direct-
ly related to how much light it can gather. The larger the aper-
ture, the more magnification is possible. In general, a figure of
50x per inch of aperture is the maximum attainable for most
telescopes. Going beyond that will yield simply blurry, unsatis-
factory views. Your VersaGo E-Series 90mm refractor has an
aperture of 90mm, or 3.5 inches, so the maximum magnifica-
tion would be about 175x (3.5 x 50). This level of magnification
assumes you have ideal atmospheric conditions for observing
(which is seldom the case).
Keep in mind that as you increase magnification, the bright-
ness of the object viewed will decrease; this is an inherent
principle of the laws of physics and cannot be avoided. If mag-
nification is doubled, an image appears four times dimmer. If
magnification is tripled, image brightness is reduced by a factor
of nine!
So start by using the 25mm eyepiece, then try switching to the
10mm eyepiece later if you want to boost the magnification.
Focusing the Telescope
To focus the telescope, turn the focus wheels (Figure 8) for-
ward or back until you see your target object (e.g., stars, the
Moon, etc.) in the eyepiece. Then make finer adjustments
until the image is sharp. If you’re having trouble achieving ini-
tial focus, rack the focuser drawtube all the way in using the
focus wheels, then while looking into the eyepiece slowly turn
the focus wheels so that the drawtube extends outward. Keep
going until you see your target object come into focus. Note that
when you change eyepieces you may have to adjust the focus a
bit to get a sharp image with the newly inserted eyepiece.
What to Expect
So what will you see with your telescope? The VersaGo
E-Series 90mm Altazimuth Refractor provides great views both
in daytime and at night. The 45-degree correct-image diago-
nal provides a normal, right-side-up image, which is important
for daytime terrestrial viewing. For nighttime viewing of celes-
tial objects, while there is no “right side up” in space, the nor-
mal, upright orientation will make moving the telescope to, say,
center an object in the eyepiece very intuitive. However, if you
would prefer a 90-degree “star” diagonal for a more comfortable
viewing position when observing objects overhead, one can be
purchased separately. Note, though, that a standard star diago-
nal will render a mirror reversed image in the eyepiece, rather
than a correctly oriented image. So we do not recommend a
star diagonal for terrestrial viewing.
For celestial viewing, you should be able to see bands on
Jupiter, the rings of Saturn, craters on the Moon, the waxing
and waning of Venus, and many bright deep-sky objects such
as star clusters and nebulas. Do not expect to see colors in faint
objects as you do in photographs, however. Most galaxies and
nebulas will appear gray in color. Unlike a camera, which can
record colors of faint objects in long exposures, our eyes are
not sensitive enough to see such color except in a few of the
brightest ones.
Celestial Objects to Observe
A. The Moon
With its rocky surface, the Moon is one of the easiest and most
interesting objects to view with your telescope. Lunar craters,
maria, and even mountain ranges can all be clearly seen from a
distance of 238,000 miles away! With its ever-changing phases,
you’ll get a new view of the Moon every night. The best time
to observe our one and only natural satellite is during a partial
phase, that is, when the Moon is not full. During partial phases,
shadows are cast on the surface, which reveal more detail,
especially right along the border between the dark and light
portions of the disk (called the “terminator”). A full Moon is too
bright and devoid of surface shadows to yield a pleasing view.
Make sure to observe the Moon when it is well above the hori-
zon to get the sharpest images.
Use an optional Moon filter to dim the Moon when it is very
bright. It simply threads onto the bottom of the eyepieces (you
must first remove the eyepiece from the focuser to attach a fil-
ter). You’ll find that the Moon filter improves viewing comfort,
and helps to bring out subtle features on the lunar surface.
B. The Planets
The planets don’t stay put like the stars, so to find them you
should refer to the monthly star charts at OrionTelescopes.com,
or to charts published monthly in Astronomy, Sky & Telescope,
or other astronomy magazines. Venus, Mars, Jupiter, and
Saturn are the brightest objects in the sky after the Sun and the
Moon. Other planets may be visible but will likely appear star-
like. Because planets are quite small in apparent size, optional
higher-power eyepieces or a Barlow lens are recommended
and often needed for detailed observations.
B. The Sun
You can change your nighttime telescope into a daytime Sun
viewer by installing an optional full-aperture solar filter over the
front opening of the telescope. The primary attraction is sun-
spots, which change shape, appearance, and location daily.
Sunspots are directly related to magnetic activity in the Sun.
Many observers like to make drawings of sunspots to monitor
how the Sun is changing from day to day.
IMPORTANT NOTE: Do not look at the sun with any optical
instrument without a professionally made solar filter,
or permanent eye damage could result.
D. The Stars
Stars will appear like twinkling points of light. Even powerful
telescopes cannot magnify stars to appear as more than a point
of light. You can, however, enjoy the different colors of the stars
and locate many pretty double and multiple stars. The famous
= 60x
600 mm
10 mm
= Magnification
Telescope Focal Length (mm)
Eyepiece Focal Length (mm)
