Use The Specifications To Calcu- Late The Magnification Of Your Eyepiece - Meade Infinity AZ 80 Instruction Manual

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12
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
Focal ratio
Mounting type
Viewfinder
Infinity 102 model:
Objective lens diameter
Optical tube focal length
80mm(3.2")
Focal ratio
400mm
Mounting type
f/5
Viewfinder
Alt-azimuth
Red-dot
What do the specifications mean?
Optical tube focal length is the distance light
travels in the telescope before being brought
90mm(3.5")
to focus in you eyepiece. Depending on the
600mm
telescope model, the focal length is either
400mm or 600mm long. Look at the specifi-
cation 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 objec-
tive 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
f/6.7 Hubble Space Telescope's objective lens
Alt-azimuth has a diameter of 2.4 meters (that's 7.8 feet
Red-dot across!).
The focal ratio helps determine how fast the
photographic speed of a telescope is. The
102mm(4.0")
lower the focal ratio number, the faster the
600mm
exposure. f/5 is faster than f/10. The faster
f/5.9
the ratio, the shorter the exposure time is
Alt-azimuth
needed when a camera is hooked up to the
Red-dot
telescope. For example, the Infinity 80 tele-
scope 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 CALCU-
LATE 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
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