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8" LX10 Schmidt-Cassegrain Telescope Instruction Manual
 B. FIRST OBSERVATIONS
IMPORTANT NOTICE! Never use a telescope or spotting scope to look at the Sun! Observing the Sun, even for the shortest fraction of a second, will cause irreversible damage to your eye as well as physical damage to the telescope or spotting scope itself.
Before proceeding, refer to Fig. 1, Fig. 2 and Fig 3 to confirm that you have assembled your LX10 correctly and to familiarize yourself with the location of the telescope's various controls. Explanations of terminology such as "Right Ascension" and "Declination" will be provided later in this manual. Following this brief review, you are ready for your first observations with the LX10.

Using both hands, remove the metal dust cover over the correcting plate (1, Fig. 1) by gently pulling it away from the telescope. Be careful not to touch the correcting plate. (If you do, refer to Telescope Troubleshooting, Maintenance and Servicing, Part 4). To protect the correcting plate, replace the dust cover whenever the telescope is not in use.

Figure 8

Figure 9

Caution: Never turn the Right Ascension (R.A.) slow-motion control knob (4, Fig. 8), or attempt to move the optical tube manually when the R.A. lock (3, Fig. 8) is in the LOCKED position; such movement may damage the internal gears.

The Declination (Dec) slow-motion control knob (2, Fig. 8) has a fixed travel length. At some point after turning the Dec slow-motion control continuously in the same direction, the control will become difficult to turn. Do not attempt to turn the Dec slow-motion control past this point or damage to the internal mechanism will result. Instead, back-off the Dec slow-motion control by turning the control about 50 turns in the opposite direction. Unlock the Dec lock (Fig. 9) and move the telescope manually to center the object; then resume use of the Dec slow-motion control. Never attempt to move the optical tube manually when the Dec lock (1, Fig. 9) is in the LOCKED position.

Select an object that is approximately 100 feet distant( e.g., the top of a telephone pole) and sight along the optical tube to "aim" the telescope at the object. Look through the eyepiece of the main telescope and turn the focus knob (1, Fig. 8) clockwise or counterclockwise until the object is in focus.

Once your selected object is in focus, with the R.A. lock UNLOCKED, and the Dec lock LOCKED, use the R.A. slow-motion control knob (4, Fig. 8) and the Dec. slow-motion control knob (2, Fig. 8) to center the object in the field of view.

Objects viewed through the telescope's eyepiece will be correctly oriented up-and-down but will be reversed left-for-right.

[ toc ] Telescope Controls

An important array of controls facilitates operation of the LX10 telescope. Be sure to acquaint yourself with all of these controls before attempting observations through the telescope.

Focus Knob (1, Fig. 8): Turning this knob causes a finely-controlled internal motion of the telescope's primary mirror to achieve precise focus of the telescopic image. The LX10 can be focused on objects from a distance of about 25 feet to infinity.

Dec Slow-Motion Control (2, Fig. 8): With the Dec lock in the fully locked position (with the lever pushed forward towards the front end of the optical tube), the Dec slow-motion control knob permits manual slow-motions of the telescope in Declination.

R.A. Lock (3, Fig. 8): Locking and unlocking the R.A. lock is accomplished by moving the R.A. lock lever all the way to the left for fully locked, to the center for partially locked, and all the way to the right for fully unlocked. Remember: never attempt to move the optical tube manually when the R.A. lock is fully locked.

R.A. Slow-Motion Control (4, Fig. 8): With the R.A. lock either fully unlocked or partially locked, the R.A. slow-motion control knob permits manual slow-motions of the telescope in a horizontal direction.

Dec Lock (1, Fig. 9): Locking and unlocking the Dec movement of the optical tube is accomplished by moving the Dec lock lever all the way forward for fully locked, or by moving the Dec lock lever all the way back (towards the eyepiece) for fully unlocked. Remember: never attempt to move the optical tube manually when the Dec lock is locked.

[ toc ] Magnifications

The magnification, or power, at which a telescope is operating is determined by two factors: the focal length of the telescope and the the focal length of the eyepiece employed.

The Meade LX10 is supplied with a 25mm eyepiece as standard equipment. Eyepiece focal length, 25mm, is printed on the side of the eyepiece.

The telescope focal length is, roughly speaking, the distance that light travels inside the telescope before reaching a focus. In the mirror-lens design of the LX10, however, this focal length is, in effect, compressed by the telescope's secondary mirror, so that a long effective telescope focal length is housed in the short LX10 optical tube.

The LX10's focal length is 2000mm, or about 80 inches. If the LX10 were a classical refracting-type of telescope, its optical tube would thus be more than 6 feet long instead of the LX10's more compact 16" tube length.

On a given telescope, such as the LX10, different eyepiece focal lengths are used to achieve different magnifications, from low to high. The supplied 25mm eyepiece yields 80X. Optional eyepieces and the #140 2x Barlow Lens are available for powers from 36X to over 500X (see Optional Accessories).

To calculate the magnification obtained with a given eyepiece, use this formula:

Power = Telescope Focal Length ÷ Eyepiece Focal Length

Example: The power obtained with the LX10 with the 25mm eyepiece is:

Power = 2000mm ÷ 25mm = 80X

The most common mistake of the beginning observer is to "overpower" the telescope and to use high magnifications which the telescope's aperture and typical atmospheric conditions cannot reasonably support.

Keep in mind that a smaller, brighter, but well-resolved image is far superior to a larger but dim and poorly-resolved image. Powers above about 300X should be employed with the LX10 only under the steadiest atmospheric conditions.

Most observers will want to have 3 or 4 eyepieces and perhaps the #140 2x Barlow lens to achieve the full range of reasonable magnifications. See Optional Accessories for further details.


[ toc ] THE VIEWFINDER

The LX10, as with almost all astronomical telescopes, presents a fairly narrow field of view to the observer. As a result it is sometimes difficult to locate and center objects in the main telescope's field of view.

The viewfinder, by contrast, is a low-power, wide-field sighting scope with crosshairs that enables the easy centering of objects in the main telescope's field. Standard equipment with the LX10 is a viewfinder of 6-power and 30mm aperture, called a "6 x 30mm viewfinder."

[ toc ] Focusing the Viewfinder

The viewfinder has been factory prefocused to objects located at infinity. Individual eye variations, however, may require that the viewfinder be refocused to your eye. Looking through the viewfinder, point the telescope at a distant object; if the viewfinder image is not sufficiently in focus for your eye, it may be refocused as follows:

Loosen the viewfinder focus lock ring (3, Fig. 7) at the objective-lens-end of the viewfinder, enabling rotation of the objective lens cell clockwise or counterclockwise for precise focusing while looking at a distant object through the viewfinder. After a precise focus has been achieved, tighten the viewfinder focus lock ring against the objective lens cell to lock the focus in place. Note that no focusing is possible from the eyepiece end of the viewfinder.

[ toc ] Alignment of the Viewfinder

In order for the viewfinder to be useful, it must first be aligned with the main telescope, so that both the viewfinder and the main telescope are pointing at precisely the same position. Follow this procedure to align the viewfinder:

With the viewfinder properly mounted on the main telescope, and with the ON/OFF switch on the control panel in the OFF position, look through the eyepiece of the main telescope to locate and focus on a stationary object at least 200 yards distant. Center the object precisely in the main telescope's field and lock both the R.A. lock and the Dec lock so that the object can not move in the field.

Now, while looking through the viewfinder, turn one or more of the 6 thumbscrews until the crosshairs of the viewfinder are precisely centered on the object already centered in the main telescope. All six screws must be tight when complete so that the viewfinder will not move.

The viewfinder is now aligned to the main telescope. Unless the alignment screws are disturbed, the viewfinder will remain aligned indefinitely.

[ toc ] Using the Viewfinder

Now, to locate any object, terrestrial or astronomical, first center the object on the cross hairs of the viewfinder; the object will then also be centered in the field of view of the main telescope.

Note: When you wish to use higher observing magnifications on a given object, first locate, center, and focus the object using a low-power eyepiece (e.g., the 25mm eyepiece). Objects are easier to locate and center at low powers; higher powers may then be employed simply by changing eyepieces.


[ toc ] THE EQUATORIAL WEDGE

The standard-equipment equatorial wedge permits the use of the LX10 in an astronomical, or "equatorial" mode. The wedge accepts the drive base of the LX10 fork mount.

Caution: Never attempt to observe through the telescope without the telescope being attached to a suitable tripod. Do not place the telescope-with-wedge-only on a tabletop. In such a case the telescope may become seriously imbalanced, to the point where it may actually tip over.

The Meade equatorial wedge is of modern design, with several important features incorporated to facilitate observations with the LX10.

Figure 10

  • After you have used the wedge, you will learn how its functional design features enhance your ability to operate the telescope. These design features include:

  • Attachment of the wedge to the field tripod by means of only one manual knob (4, Fig. 10).

  • Quick azimuth (horizontal) orientation of the telescope, by loosening the 3" manual knob (4, Fig. 10).

  • Fast adjustment of latitude angle with the tilt angle adjustment lock (3, Fig. 10).

The importance of these features will be made clear below.



[ toc ] KEYPAD HAND CONTROLLER

The LX10's standard-equipment keypad hand controller (Fig. 11) plugs into the telescope's control panel and is designed for micro-guiding the telescope during long exposure astrophotography, yielding precise corrections in R.A. at 2x speed.

For single-axis 2x corrections in R.A., press and hold either the "W" or "E" key as necessary. Release to resume normal sidereal tracking speed of the telescope's main drive system.

Note: The word "sidereal" refers to the rate at which stars appear to move as the Earth rotates on its axis. Thus, "sidereal-rate tracking" refers to the speed at which the telescope's motor drive moves the telescope, in order that stars appear stationary when viewed through the telescope.

To facilitate long-exposure astrophotography where minor corrections of the telescope's position are required in both R.A. and Dec, the optional Meade LX10 Electric Declination Motor (Fig. 13) permits dual-axis control by activating the "N" (north) and "S" (south) keys of the keypad (see Optional Accessories).

With the optional Declination motor attached, making minor corrections in Declination during long-exposure astrophotography is accomplished by pressing and holding either the "N" or "S" keys of the keypad. When you have completed the correction, release the selected key.

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