Meade Infinity 80mm User Manual - Page 14

HAVE A GOOD TIME, 12 ASTRONOMY IS FUN! Focal ratio Mounting type Viewfinder f/6.7 Alt-azimuth Red-dot SPECIFICATIONS Infinity 80 model: Objective lens diameter Optical tube focal length Focal ratio Mounting type Viewfinder Infinity 90 model: Objective lens diameter Optical tube focal length 80mm(3.2") 400mm f/5 Alt-azimuth Red-dot 90mm(3.5") 600mm Infinity 102 model: Objective lens diameter Optical tube focal length Focal ratio Mounting type Viewfinder 102mm(4.0") 600mm f/5.9 Alt-azimuth Red-dot What do the specifications mean? Optical tube focal length is the distance light travels in the telescope before being brought to focus in you eyepiece. Depending on the telescope model, the focal length is either 400mm or 600mm long. Look at the specification table to find out your telescopes focal length. Objective lens diameter is how big the front lens is on your scope. Telescopes are always described by how large their objective lens is. Depending on your telescope model, the lens diameter is either 80mm, 90 or 102mm. Other telescopes are 50mm, 8 inches, 16 inches, or even 3 feet in diameter. The Looking at or near the Sun will cause irreversible damage to your eye. Do not point this telescope at or near the Sun. Do not look through the telescope as it is moving. Hubble Space 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 shorter the exposure time is needed when a camera is hooked up to the telescope. For example, the Infinity 80 telescope has fast focal ratio at f/5. Sometimes, astronomers use focal reducers to make slow exposure telescopes have faster focal ratios. Alt-azimuth 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. USE THE SPECIFICATIONS TO CALCULATE THE MAGNIFICATION OF YOUR EYEPIECE The power of a telescope is how much it magnifies objects. For an Infinity 90, the 26mm eyepiece magnifies an object 23.1