1

2

3

 

Fig. 33a: Defocused star images. Misaligned (1, 2), Aligned

Fig. 33b: Collimation screws.

Caution: Do not force the three collimation

screws past their normal travel and do not loosen them more than two full turns in a counterclockwise direction or the secondary mirror may come loose from its support. You will find that the adjustments are very sensitive, usually requiring only one-half turn or less to produce the desired result.

b.While looking at the defocused star image, notice which direction the darker shad- ow is offset in the ring of light or notice which part of the ring is the thinnest (1, Fig. 33a). Place your index finger in front of the telescope so that it touches one of the collimation set screws. You will see the shadow of your finger in the ring of light. Move your finger around the edge of the black plastic secondary mirror sup- port until you see the shadow of the finger crossing the thinnest part of the ring of light. At this point, look at the front of the telescope where your finger is aiming. It will either be pointing directly at a set screw, or it will be between two set screws aiming at the set screw on the far side of the black plastic secondary mirror sup- port. This is the set screw that you will adjust.

c.Using the Autostar's Arrow keys at the slowest slew speed, move the defocused image to the edge of the eyepiece field of view (2, Fig. 33a), in the same direc- tion as the darker shadow is offset in the ring of light.

d.Turn the set screw that you found with the pointing exercise while looking in the eyepiece. You will notice that the star image will move across the field. If while turning the defocused star image flies out of the eyepiece field, then you are turn- ing the screw the wrong way. Turn the opposite direction and bring the image back to the center of the field.

e.If the screw you are turning becomes very loose, tighten the other two screws by even amounts. If the screw you are turning gets too tight, unthread the other two by even amounts.

f.When you bring the image to center (3, Fig. 33a), carefully examine the evenness of the ring of light (concentricity). If you find that the dark center is still off in the same direction, continue to make the adjustment in the original turning direction. If it is now off in the opposite direction, you have turned too far and you need to turn in the opposite direction. Always double check the image in the center of the field of the eyepiece.

g.You may find after your initial adjustment that the dark center is off in a new direc- tion (e.g., instead of being off side-to-side it is now off in an up-and-down direc- tion). In this case repeat steps b through f to find the new adjustment screw.

h.Now try a higher power eyepiece (e.g., 9mm or less) and repeat the above tests. Any lack of collimation at this point will require only very slight adjustments of the three set screws. You now have good collimation of the optics.

i.As a final check of alignment, examine the star image in focus with the higher power eyepiece as suggested (j), under good viewing conditions. The star point should appear as a small central dot (commonly referred to as an “Airy disc”) with a diffraction ring surrounding it. To give a final precision collimation, make extremely slight adjustments of the three set screws, if necessary, to center the Airy disc in the diffraction ring. You now have the best alignment of the optics pos- sible with this telescope.

43

Page 43
Image 43
Meade LXD75 instruction manual Defocused star images. Misaligned 1, 2, Aligned

LXD75 specifications

The Meade LXD75 series represents a remarkable range of telescopes designed for both amateur astronomers and advanced users seeking high-quality performance at an affordable price. Known for its robust construction and innovative technology, the LXD75 aims to provide a user-friendly experience while catering to the demands of stargazers looking for sophistication in their equipment.

One of the main features of the LXD75 is its advanced German equatorial mount, which provides exceptional stability and tracking accuracy. This mount is equipped with dual-axis servo motors facilitating smooth movements, making it easy to locate and follow celestial objects. The LXD75 also includes a built-in autostar system featuring a database of over 30,000 celestial objects, allowing users to effortlessly navigate the night sky with a push of a button.

The LXD75 series includes several models, each with different optical configurations to suit the preferences of various users. The telescopes come with either an achromatic refractor or Schmidt-Cassegrain optical design, providing clear and bright images. The Schmidt-Cassegrain models offer a compact design with a fast focal ratio, making them excellent for both astrophotography and visual observation.

In terms of build, the Meade LXD75 features high-quality optics with multi-coated lenses, reducing glare and enhancing light transmission. This results in sharper and brighter images, making it easier to observe delicate details on planets, the moon, and deep-sky objects. The telescope tubes are crafted from durable materials, ensuring longevity and resilience against the elements.

Another characteristic worth noting is the ease of setup and operation. The LXD75 mount comes equipped with adjustable legs and can be easily assembled, requiring minimal tools. The intuitive control system also features a user-friendly interface, allowing both novices and experienced astronomers to operate the telescope with confidence.

For astrophotography enthusiasts, the LXD75 provides excellent support, with a wide range of accessories available to enhance imaging capabilities. The mount can accommodate various cameras, providing flexibility for capturing stunning astronomical photographs.

In summary, the Meade LXD75 series delivers a robust combination of features, technologies, and characteristics designed to meet the needs of both amateur and advanced astronomers. With its reliable mount, quality optics, and ease of use, the LXD75 ensures that stargazers can enjoy the wonders of the universe with clarity and precision.