Celestron 31058, 31056 instruction manual Newtonian Optical System

The Newtonian Optical System

FAMILIAR WITH THE CORRECTOPERATINGPROCEDURESOF YOUR TELESCOPE.

NEVER USE AN EYEPIECE SOLAR FILTER OR A HERSCHEL WEDGE SOLAR FILTER. INTERNAL HEAT BUILD-UP INSIDE THE TELESCOPE CAN CAUSE THESE DEVICES TO CRACK OR BREAK.

NEVER POINT YOUR TELESCOPE AT THE SUN UNLESS USING THE PROPER SOLAR FILTER. WHEN USING A SOLAR FILTER, ALWAYS COVER THE FINDER. ALTHOUGH SMALL IN APER- TURE, THE FINDER HAS ENOUGH LIGHT GATHERING POWER TO POSSIBLY CAUSE PERMANENT AND IRREVERS- IBLE EYE DAMAGE. THE IMAGE PROJECTED BY THE FINDER IS HOT ENOUGH TO BURN SKIN OR CLOTHING.

The Newtonian reflector was developed by Isaac Newton in the late 1600’s and therefore carries his name. This type of telescope uses a primary mirror to focus the light rays it collects. In addition to focusing the light, the mirror also redirects them toward the front of the telescope tube where the light entered. Near the front of the tube, the light rays are intercepted by a small flat secondary mirror (some- times called an elliptical flat) and directed out of the telescope tube at a 90° angle to the incoming light rays (see figure 1-1). It is here that the eyepiece is placed to view the image formed by the telescope. Because mirrors, not lenses, are used, much larger light gathering areas can be used without fear of gravity distorting them. Furthermore, these larger aperture systems become much more portable that comparable refractors.

Figure 1-1

This cross sectional diagram shows the light path of the Newtonian optical system. All optical elements are labeled.

Introduction • 7