Meade 2045 - Magnification; The Viewfinder; Celestial Coordinates

powers. This image shift is caused by very small lateral motions of the primary mirror as it moves toward
or away from the secondary mirror during the focusing procedure.
MAGNIFICATION
The magnification, or power, of the telescope depends on two optical characteristics: the focal length of
the main telescope, and the focal length of the eyepiece used during a particular observation. The focal
length of the Model 2045 telescope is fixed at 1000mm. To calculate the power in use with a particular
eyepiece, divide the focal length of the eyepiece into the focal length of the main telescope. For example,
using the MA 25mm eyepiece supplied with the Model 2045, the power is calculated as follows:
Power = 1000mm + 25mm = 40X
Similarly, with an MA 9mm eyepiece, a magnifying power of 1000mm/9mm, or 111X, results. The type of
eyepiece (whether "MA” Modified Achromatic, "OR" Orthoscopic, "SP" Super Plossl, etc.) has no bearing
on magnifying power but does affect such optical characteristics as field of view, flatness of field and color
correction.
When beginning observations on a particular object, start with a low-power eyepiece. Get the object well
centered in the field of view and sharply focused. Then try the next step up in magnification. If the image
starts to become fuzzy as you work into higher magnifications, then back down to a lower power. The
atmospheric steadiness is not sufficient to support high powers at the time you are observing. Keep in
mind that a bright, clearly resolved but small image will show far more detail than a dimmer, poorly
resolved larger image.
Optional eyepieces and the #126 2X Telenegative Amplifier are available for higher and lower powers
through the telescope.
THE VIEWFINDER
The 5x24mm viewfinder has been prefocused at infinity. Should this focusing need adjustment for your
eye, loosen the knurled collar at the objective lens end of the viewfinder (the end opposite where you
observe through the finder), enabling rotation of the objective lens cell, forward or backward for precise
focusing. Tighten down the knurled collar against the objective lens cell to lock the focus in place. Note
that no focusing is possible or necessary at the eyepiece end of the finder scope. The viewfinder will
require alignment, or collimation, to the main telescope. Using the supplied 25mm eyepiece, point the
main telescope at some easy to find land object (e.g. the top of a telephone pole or corner of a building)
at least 200 yards distant. Center a well-defined object in the main telescope. Then, using one of the hex
wrenches provided, tighten or loosen, as appropriate, the 3 collimation screws located on the finder’s rear
bracket ring until the cross hairs of the finder are precisely centered in the main telescope. With this
collimation accomplished, objects located first in the wide-field viewfinder will then be centered in the
main telescope’s field of view. Note that images seen in the viewfinder are upside-down from their
counterparts viewed through the main telescope with diagonal prism.
CELESTIAL COORDINATES
For terrestrial observing, setting the Model 2045 flat on the bottom of its drive base is a completely
satisfactory method for tracking or observing objects in the telescope. For astronomical observing,
however, the situation is quite different: objects move fairly rapidly through the field of view (due to
Earth’s axial rotation) and they move at an angle to the horizon, depending on the observer’s latitude. It
is for these reasons that the Model 2045 is equipped with two highly convenient features: a means of
tilting the entire telescope to an angle (thereby facilitating astronomical tracking); and an electronic pulse
motor drive for automatic tracking. Before discussing these points, some background in celestial
coordinates is required.
Analogous to the Earth-based coordinate system of latitude and longitude, celestial objects are mapped
according to a coordinate system on the "celestial sphere," the imaginary sphere on which all stars