Meade 70AZ-ADS instruction manual Specifications, What do the specifications mean?

cause image movement.

Let your eyes “dark-adapt”: Allow five or ten minutes for your eyes to become “dark adapted” before observing. Use a red-filtered flashlight to protect your night vision when reading star maps, or inspecting the telescope. Do not use use a regular flash-light or turn on other lights when observing with a group of other astronomers. You can make your own red filtered flashlight by taping red cellophane over a flashlight lens.

Viewing through windows: Avoid setting up the telescope inside a room and observing through an opened or closed window pane. Images may appear blurred or distorted due to temperature differences between inside and outside air. Also, it is a good idea to allow your telescope to reach the ambient (surrounding) outside temperature before starting an observing session.

When to observe: Planets and other objects viewed low on the horizon often lack sharpness—the same object, when observed higher in the sky, will appear sharper and have greater contrast. Try reducing power (change your eyepiece) if your image is fuzzy or shimmers. Keep in mind that a bright, clear, but smaller image is more interesting than a larger, dimmer, fuzzy one. Using too high a power eyepiece is one of the most common mistakes made by new astronomers.

Dress Warm: Even on summer nights, the air can feel cool or cold as the night wears on. It is important to dress warm or to have a sweater, jacket, gloves, etc., nearby.

Know your observing site: If possible, know the location where you will be observing. Pay attention to holes in the ground and other obstacles. Is it a location where wild animals, such as skunks, snakes, etc., may appear? Are there viewing obstructions such as tall trees, street lights, headlights and so forth? The best locations are dark locations, the darker the better. Deep space objects are easiest to see under dark skies. But it is still possible to observe even in a city.

Surf the Web and visit your local library: The internet contains a huge amount of astronomical information, both for children and adults. Check out astronomy books from your library. Look for star charts—these are available on a monthly basis in Astronomy and Sky and Telescope magazines.

SPECIFICATIONS

Optical tube focal length . . . . . 350mm

Objective lens diameter . . 70mm (2.8")

Focal ratio . . . . . . . . . . . . . . . . . . . . f/5

Mounting type . . . . . . . . . . . Altazimuth

Viewfinder Size . . . . . . . . . . . . . 8 x 21

Barlow . . . . . . . . . . . . . . . . . . . . . . . 2X

What do the specifications mean?

Optical tube focal length is simply a measurement of the length of the optical tube. In other words, this is the distance light travels in the telescope before being brought to focus in you eyepiece. Your tube is 350mm long.

Objective lens diameter is how big the lens is on your scope. Telescopes are always described by how large their objective lens is. Your telescope is 70mm or 2.8 inches. Other telescopes are 90mm, 8 inches, 16 inches, or even 3 feet in diameter. The Hubble Telescope’s objective lens has a diameter of 2.4 meters (that’s 7.8 feet across!).

The focal ratio helps determine how fast the photographic speed of a telescope is. The lower the focal ratio number, the faster the exposure. f/5 is faster than f/10. The faster the ratio, the faster exposure time is needed when a camera is hooked up to the telescope. Your telescope has a faster focal ratio at f/5. Sometimes, astronomers use focal reducers to make slow exposure telescopes have faster focal ratios.

Altaz mounting simply means your telescope moves up and down (altitude or “alt”), and side to side, (azimuth or “az”). Other mounting configurations are available for other telescopes, such as equatorial mounting.

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