Meade RCX400TM Observing, Choosing an Eyepiece, To focus the telescope eyepiece, Presets

Important Note:

Objects appear upside-down and reversed left-for-right when observed in the viewfinder. Objects viewed through the telescope eye- piece when inserted into the diagonal prism assembly appear right-side-up, but reversed left-for-right.

This image inversion is of no consequence when observ- ing astronomical objects and, in fact, all astronomical tele- scopes yield inverted images.

During terrestrial observing, where a fully-correctly-orient- ed image (right-side-up and correct left-for-right) is desir- able, an optional #928 45° Erecting Prism and optional 1.25” eyepiece holder are available. See OPTIONAL ACCESSORIES, pages 48 - 50.

FOCUS

KEY

Fig. 25: Focus is all-digital, using the Focus key (the #4 Number key) of the AutoStar II handbox.

OBSERVING

Choosing an Eyepiece

A telescope’s eyepiece magnifies the image formed by the telescope’s main optics. Each eyepiece has a focal length, expressed in millimeters, or “mm.” The smaller the focal length, the higher the magnification. For example: An eyepiece with a focal length of 9mm has a higher magnification than an eyepiece with a focal length of 26mm.

Your telescope comes supplied with an UltraWide 24mm eyepiece which gives a wide, comfortable field of view with high image resolution.

Low power eyepieces offer a wide field of view, bright, high-contrast images, and eye relief during long observing sessions. To find an object with a telescope, always start with a lower power eyepiece such as the UltraWide 24mm. When the object is locat- ed and centered in the eyepiece, you may wish to switch to a higher power eyepiece to enlarge the image as much as practical for prevailing seeing conditions. For infor- mation about optional eyepieces for your telescope, see OPTIONAL ACCESSORIES, pages 48 - 50.

The power, or magnification of a telescope is determined by the focal length of the tel- escope and the focal length of the eyepiece being used (an eyepiece's focal length is printed on the side of the eyepiece). To calculate eyepiece power, divide the tele- scope's focal length by the eyepiece's focal length. For example: A 24mm eyepiece is supplied with RCX400 models. The focal length of the 12" f/8 RCX400 is 2438mm (see SPECIFICATIONS, pages 54 - 56).

Eyepiece Power = Telescope focal length ÷ Eyepiece focal length Eyepiece Power = 2438mm ÷ 24mm

Eyepiece Power = 102

The eyepiece power, or magnification is therefore 102X (approximately).

Note: For a list of magnification ratings of the eyepieces available for the RCX400 telescopes, see OPTIONAL ACCESSORIES, pages 48 - 50.

Focusing the Telescope

All focusing of the RCX400 is performed digitally, using AutoStar II’s Focus key (number key 4). The Focus key functions as a toggle key:

JPress the Focus key the first time to focus the telescope eyepiece and to control the speed at which you focus.

JPress the Focus key again to set and adjust up to nine focus presets.

To change the focus speed:

1.Press the Focus key once. “Focuser: Fast (or the current speed)” displays for two seconds. Use one of the Scroll keys to scroll through the list of 4 available focus speeds: Fast, Medium, Slow, Fine. Scroll through the list until the speed you desire displays. Choose a focus speed with which you feel comfortable.

To focus the telescope eyepiece:

1.Press the Focus key once. “Focuser: Fast (or the current speed)” displays. After

two seconds, “Focuser: Position = XX” displays. “XX” stands for a number value in decimal millimeters.

2.Point the telescope at a distant object. Look in the eyepiece and use the Arrow keys until the image in the eyepiece is in sharp focus.

Presets:

If you “Park” your telescope, you do not have to refocus the telescope each time you use it. Nine preset focus positions are available, and they operate much like presets on a car radio—everyone can have their own favorite station, or in this case, their own personalized focus. You can set one preset to take into account your own eyesight, one for your observing partner (who may wear glasses), one for your camera’s focus, and so forth.

Three preset menus are available. Use the Define Preset menu to assign a preset, use the GoTo Preset menu to select a preset you have previously assigned, and use

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