Meade LNT Instruction Manual download pdf (Page 14)

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.

our telescope comes supplied with a Super Plössl 26mm 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 Super Plössl 26mm. When the object is located 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 information about optional eyepieces for the

LX90, see "OPTIONAL ACCESSORIES," page 41.

NOTE: Seeing conditions vary widely from night-to-night and site-to-site. Turbulence

in the air, even on an apparently clear night, can distort images. If an image

appears fuzzy and ill-defined, back off to a lower power eyepiece for a more well-

resolved image (

Fig. 8a and 8b).

The power or magnification of a telescope is determined by the focal length of the telescope

and the focal length of the eyepiece being used. To calculate eyepiece power, divide the

telescope's focal length by the eyepiece's focal length. For example, a 26mm eyepiece is

supplied with the LX90. The focal length of the LX90 is 2000mm (see "SPECIFICATIONS,"

page 45).

Telescope Focal Length 2000mm

Eyepiece Focal Length 26mm

2000 ≠÷ 26 = 77≠

The eyepiece power, or magnification, is therefore 77X (approximately).

Using SmartFinder

As with most astronomical telescopes, an eyepiece presents a narrow field of view to the

observer. As a result it is sometimes difficult to locate objects just using your eyepiece. The

SmartFinder has a projected red dot that helps you to locate objects as you move your

telescope. See page 10 for more information about the SmartFinder’s Finder Set menu.

To turn on SmartFinder’s red dot (continuous, without blinking):

1. Press and hold AutoStar’s MODE key for two seconds. R.A and Dec. coordinates

display.

2. Keep pressing the Scroll Down key until “Finder Set: Set” displays.

3. Press ENTER. “Finder Set: Intensity” displays.

4. Press ENTER. “Finder: Blink On” displays.

5. Press Scroll Down key. A time value, in seconds, displays. For example, “00.5” may

displa

“00.5”

is the amount of time, in seconds, that the red dot will blink “on.”

(For this example, you may select or enter any value except “00.0.”) Press ENTER.

6. Press Scroll Down key“Finder: Blink Off” displays.

Press ENTER.

Use the Number k

ys to enter “00.0” or press the Scroll Down

key until “00.0” displays. “00.0” is the amount of time in seconds that the

red dot will remain “off.” This value, along with the value you chose in the

“Finder: Blink On” menu, allows the red dot to remain on without blinking.

“00.0”

means there is no “off” time, so the dot will remain on continuously,

without blinking.

Use these men

us to set other b

link r

ates

For example, If you select “00.2” in

the Blink On men

u, and

“00.1” in the Blink Off menu, the red dot will blink on

or .2 seconds and then b

link off f

or .1 second, and then repeat the cycle until

you change the values again.

9. Press and hold MODE to exit this function.

Chec

k this alignment on a celestial object, such as the Moon or a bright star, and make

any necessary refinements to the intensity and blink rate, using the method outlined

above.

NOTE:

For a list of

magnification

ratings of the eye-

pieces available for

the LX90 telescope,

see "OPTIONAL

ACCESSORIES,"

page 41.

NEVER point the

telescope directly at

or near the Sun at

any time! Observing

the Sun, even for the

smallest fraction of a

second, will result in

instant and

irreversible eye dam-

age, as well as

physical damage to

the telescope itself.

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Meade LNT Instruction Manual Page 14

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