Orion 70MM AZ Using Your Telescope, Aligning the EZ Finder, Replacing the EZ Finder II Battery

Aligning the EZ Finder II

When the EZ Finder II is properly aligned with the telescope, an object that is centered on the EZ Finder II’s red dot should also appear in the center of the field of view of the telescope’s eyepiece. Alignment of the EZ Finder II is easiest during day- light, before observing at night. Aim the telescope at a distant object at least 1/4 mile away, such as a telephone pole or chimney and center it in the telescope’s eyepiece. Now, turn the EZ Finder II on and look through it. The object will appear in the field of view near the red dot.

Note: The image in the eyepiece of the Observer 70 will be reversed from left-to-right. This is normal for a refrac- tor telescope using a mirror star diagonal.

Without moving the telescope, use the EZ Finder II’s azimuth (left/right) and altitude (up/down) adjustment knobs (Figure 6) to position the red dot on the object in the eyepiece.

When the red dot is centered on the distant object, check to make sure that the object is still centered in the telescope’s field of view. If not, recenter it and adjust the EZ Finder II’s alignment again. When the object is centered in the tele- scope’s eyepiece and on the red dot, the EZ Finder II is prop- erly aligned with the telescope. Figure 7 shows how the view through the EZ Finder may look while you are aligning it.

Once aligned, EZ Finder II will usually hold its alignment even after being removed from its bracket. If the EZ Finder II’s bracket is removed entirely from the optical tube then realign- ment will be needed.

Replacing the EZ Finder II Battery

Should the battery ever need replacing, 3-volt lithium batter- ies are available from many retail outlets. Remove the old bat- tery by inserting a small flat-head screwdriver into the slot on the battery cover (Figure 3) and gently prying open the cover. Then carefully pull back on the retaining clip and remove the old battery. Do not overbend the retaining clip. Slide the new battery under the battery lead with the positive (+) side facing down and replace the battery cover.

6. Using Your Telescope

Choosing an Observing Site

When selecting a location for observing, get as far away as possible from direct artificial light such as street lights, porch lights, and automobile headlights. The glare from these lights will greatly impair your dark-adapted night vision. Set up on a grass or dirt surface, not asphalt, because asphalt radiates more heat, which disturbs the surrounding air and degrades the images seen through the telescope. Avoid viewing over rooftops and chimneys, as they often have warm air currents rising from them. Similarly, avoid observing from indoors through an open (or closed) window, because the tempera- ture difference between the indoor and outdoor air will cause image blurring and distortion.

Azimuth adjust- ment wheel

Altitude

adjustment Power knob wheel

Battery cover

Thumbscrews

Figure 6. The EZ Finder II reflex sight.

Figure 7.

EZ Finder II superimposes a tiny red dot on the sky, showing right where the telescope is pointed.

If at all possible, escape the light-polluted city sky and head for darker country skies. You’ll be amazed at how many more stars and deep-sky objects are visible in a dark sky!

“Seeing” and Transparency

Atmospheric conditions vary significantly from night to night. “Seeing” refers to the steadiness of the Earth’s atmosphere at a given time. In conditions of poor seeing, atmospheric turbu- lence causes objects viewed through the telescope to “boil”. If, when you look up at the sky with your naked eyes, the stars are twinkling noticeably, the seeing is bad and you will be lim- ited to viewing with low powers (bad seeing affects images at high powers more severely). Planetary observing may also be poor.

In conditions of good seeing, star twinkling is minimal and images appear steady in the eyepiece. Seeing is best over- head, worst at the horizon. Also, seeing generally gets better after midnight, when much of the heat absorbed by the Earth during the day has radiated off into space.

Especially important for observing faint objects is good “transparency”—air free of moisture, smoke, and dust. All

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