Orion 100 EQ instruction manual Terrestrial Observing, Photography

years by professional and amateur astronomers alike. Keep in mind, as with any new task, that starhopping may seem chal- lenging at first, but will become easier over time and with practice.

To starhop, only a minimal amount of additional equipment is necessary. A star chart or atlas that shows stars to at least mag- nitude 5 is required. Select one that shows the positions of many deep-sky objects, so you will have lots of options to choose from. If you do not know the positions of the constellations in the night sky, you will need to get a planisphere to identify them.

Start by choosing bright objects to view. The brightness of an object is measured by its visual magnitude; the brighter an object, the lower its magnitude. Choose an object with a visual magnitude of 9 or lower. Many beginners start with the Messier objects, which represent some of the best and brightest deep- sky objects.

Determine in which constellation the object lies. Now, find the constellation in the sky. If you do not recognize the constellations on sight, consult a planisphere. The planisphere gives an all-sky view and shows which constellations are visible on a given night at a given time.

Now, look at your star chart and find the brightest star in the con- stellation that is near the object you are trying to find. Using the finder scope, point the telescope at this star and center it in the crosshairs. Next, look again at the star chart and find another suitably bright star near the bright star currently centered in the finder. Keep in mind that the field of view of the finder scope is 7°, so you should choose another star that is no more that 7° from the first star, if possible. Move the telescope slightly, until it is cen- tered on the new star.

Continue using the stars as guideposts until you are at the approximate position of the object you are trying to find (Figure 12). Look in the telescope’s eyepiece, and the object should be somewhere in the field of view. If it’s not, sweep the telescope carefully around the immediate vicinity until the object is found.

If you have trouble finding the object, start the starhop again from the brightest star near the object you wish to view. This time, be sure the stars indicated on the star chart are in fact the stars you are centering in the eyepiece.

6. Terrestrial Observing

The AstroView 100 optical tube can be used for long-distance viewing over land. We recommend using a 45° correct-image diagonal instead of the included 90° mirror star diagonal. The correct-image diagonal will yield upright, non-reversed images and provides a more comfortable viewing angle. An optional altazimuth mount or a sturdy camera tripod, as opposed to the AstroView equatorial mount, is recommended for terrestrial viewing. This is because the equatorial mount is designed for tracking the motion of stars, and is not very easy to aim at terrestrial objects. The AstroView 100 EQ’s optical tube has a mounting block that will accept the 1/4"-20 thread- ed stud used on most camera tripods.

For terrestrial viewing, it’s best to stick with low power eye- pieces that yield a magnification of under 100x. At higher

Figure 12. Starhopping is a good way to locate hard-to-find objects. Refer to a star chart to map a route to the object that uses bright stars as guideposts. Center the first star you’ve chosen in the finder scope and telescope eyepiece (1). Now move the scope carefully in the direction of the next bright star (2), until it is centered. Repeat (3 and 4). The last hop (5) should place the desired object in the eyepiece.

powers, images rapidly lose sharpness and clarity due to “heat waves” caused by Sun-heated air.

Remember to aim well clear of the Sun, unless the front of the telescope is fitted with a professionally made solar filter and the finder scope is covered by an opaque material or removed altogether.

7. Photography

When coupled to a 35mm single-lens reflex camera, the AstroView100 EQ becomes a telephoto lens. To attach a cam- era, you need only a T-ring for your specific camera model. The T-ring attaches to your camera and threads onto the AstroView 100 EQ’s 1.25" eyepiece adapter (see Figure 3).

Use the camera’s viewfinder to frame the picture. Use the telescope’s focuser to focus the image. Tighten the focus lock thumbscrew in order to keep the telescope in focus. You may want to consider using a remote shutter release instead of the shutter release on the camera; touching the camera can vibrate the system and blur the resulting photographic image on the film.

If you would like to change the orientation of the camera rela- tive to the telescope, do so by first loosening the thumbscrews on the 2" adapter. You can then rotate the camera (and 1.25" eyepiece adapter) to the desired orientation. Retighten the thumbscrews when done.

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