Tele Vue 60 - Manual (Page 5)

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a television picture, where the closer you get to the tube, the more detail you can see, until
you get so close that you see the screen’s dot pattern. Once the dot pattern is observed, no
additional detail can be seen by moving closer to the set. The same principle applies to
telescope magnifi cation and resolution. When the resolution limit is reached (at higher
magnifi cations and with steady air), stars will appear as small discs with one or more sur-
rounding faint rings of light.
Experiment with viewing double stars or lunar detail, and you will quickly discover
those magnifi cations which are best suited to the object, your eyes, and the steadiness (seeing
conditions) of the Earth’s atmosphere. Cold, crisp winter nights offer excellent transparency
for seeing faint and elusive deep-sky objects, but the accompanying air currents (turbulence)
often will make the moon or planets appear as if they are viewed under moving water. This
is the reason that bright stars twinkle so noticeably on these nights. On the other hand,
hazy summer nights with still, “dead” air (poor transparency but good “seeing”) are often
ideal for observing fi ne lunar detail, spotting planetary features, and separating close double
stars at the highest magnifi cations.
You will also enjoy views of the Ring Nebula (M57) and the Dumbbell Nebula
(M27). Close double stars such as Epsilon Lyrae (the “Double-Double”) can be split at high
magnifi cations. Check www.televue.com for more technical articles.
6. THE TELE VUE-60 AND PHOTOGRAPHY
6.1 PHOTOGRAPHIC METHODS USING THE TELE VUE-60
The Tele Vue-60 can be used with 35mm single lens refl ex (SLR) cameras or as
an afocal system with an eyepiece and digital camera.
A) PRIME FOCUS 360mm TELEPHOTO — For 35mm cameras, remove either
the diagonal or erecting prism and install the optional 1¼" camera adapter (ACM-1250).
A “T”-ring to mate your particular brand of camera to the adapter can be obtained at any
camera store. With camera mounted, look through the viewfi nder and focus the Tele Vue-
Put a red filter over your flashlight to prevent disturbing your
eyes' dark adaptation.
Objects are best observed when they are as high overhead as
possible. By looking through less air, the amount of atmospheric
turbulence and dimming (caused by absorption) is considerably
reduced.
Faint objects can be more readily detected by using a technique
called “averted vision”. Try looking slightly away from the faint
object you would like to observe and you will notice that it ap-
pears to get brighter. This is due to the position of the more light
sensitive rods lining the outer area of the retina. Experiment with
the direction in which you avert your vision since a particular area
of your eye might be more sensitive than another.
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function is unnecessary for viewing the sky. However, mirror diagonals are used to provide
easier viewing postures for the observer. Your Tele Vue-60 telescope can be used with
either prisms or mirror diagonals, providing maximum versatility for either use. Since
prisms and mirrors are in the “light path,” they must be of very high quality, or they will
degrade the overall performance of the objective and eyepiece. (All Tele Vue prisms and
mirror diagonals are individually inspected and tested to ensure the highest quality possible.)
In order for a telescope to be properly and clearly in focus, the eyepiece must be
at the precise distance from the objective lens. This distance may vary with the type of
eyepiece as well as the distance to the object being viewed. For terrestrial viewing, where
the object distance can vary greatly, there ideally should be both gross and fi ne adjustments
in order to handle all focussing situations quickly and easily. The Tele Vue-60 can focus
from approximately 10 feet to infi nity.
Another factor affecting the focus “position” is the corrective error of the observer’s
eye (i.e. if you require eyeglasses), and whether you are wearing them or not. These vari-
ables are accommodated by the focuser, which provides the mechanical adjustment for a
range of focus positions.
That’s all there is to the basic operation of a telescope or spotting scope.
3. GETTING ACQUAINTED WITH THE TELE VUE-60
The more you know about each part of the Tele Vue-60, the quicker you will become
familiar with its use and many capabilities.
3.1 OPTICAL TUBE ASSEMBLY
The optical tube assembly is the heart of the telescope. It consists of the front lens
cell with captive dew shield, snap-on lens cover, anodized aluminum body, and focuser. The
Tele Vue-60 is an air-spaced doublet apochromatic design using the fi nest quality special
dispersion glasses. The objective produces diffraction limited resolution with color cor-
rection far exceeding that of a "classic" f/15 achromat.
The two lens elements contained in the optical tube assembly are critically aligned
to deliver all the sharpness inherent in this unique design. Never loosen the lock screws
in the lens cell as this will affect collimation and void the warranty.
The end of the dew shield is threaded to accept 77mm photographic fi lters. A fi lter
is recommended to protect the objective lens when observing in shore environments. Care
must be taken to select the highest optical quality fi lter possible so as not to affect the image
quality. It is recommended to always remove any aperture fi lter for astronomical observing.
3.2 1¼" FOCUSER
Tele Vue-60's 1¼" dual-action draw tube/helical type focuser is individually hand
fi tted to obtain a smooth and accurate focus action. A tension/lock screw is located on top
of the focuser body. It can be used to add resistance against the focuser’s draw tube. This
is especially valuable when using heavy eyepieces and cameras.