Celestron FirstScope 102AZ Telescope #21013 is an excellent choice for the observer who needs a reasonably compact wide field instrument. While not an observatory-grade telescope for the critical observer, it's an excellent all-round scope despite its very low price. It has 66% more light gathering and 25% higher resolution than an 80mm scope. Its fast f/5 focal ratio is designed to show you sweeping vistas of open clusters, nebulas, and galaxies. Nevertheless, it is still well suited for lunar and planetary observing by adding a short focal length eyepiece or two or an eyepiece/Barlow combination to increase the magnification to planetary levels. Optically, it is surprisingly good for a large aperture fast focal ratio achromatic refractor. It has a visible (but well-corrected) secondary color spectrum. Its wide contrast range, typical of a refractor, often reveals a wealth of subtle lunar and planetary detail that's washed out in the glare of larger Schmidt-Cassegrains and reflectors. Star cluster and planetary images superior to those of 8"-10" Newtonians and 8" Schmidt-Cassegrains are possible in 4" refractors such as this Celestron, given suitable seeing conditions. With the high contrast and light transmission typical of a multicoated refractor, this 4" scope is capable of a surprising amount of serious Messier and NGC catalog deep space observing, too - with faint deep space objects standing out crisply against a velvet black sky. There are dedicated refractor enthusiasts who will swear that, inside the solar system or out, if you can't see it with a 4" refractor, it's probably not worth seeing anyway. The Firstscope 102 AZ uses a 4" (102mm) 500mm focal length f/5 fully-multicoated achromatic optical tube. It's mounted on a heavy-duty manual altazimuth mount that moves up and down in altitude and right and left in azimuth, rather than in the curved path taken by an equatorial mount designed for astronomy. This makes the Firstscope 102AZ particularly well suited as a terrestrial spotting scope and 500mm (10x) f/5 telephoto lens. The mount has a convenient adjustable height aluminum tripod. An accessory tray adds rigidity to the mount and convenient storage for eyepieces. The wide 7 degree field of view (14 lunar diameters) of its 6 x 30mm straight-through astronomical finderscope makes it easy to locate deep space objects. Images are upside down and backwards in the finder, making it a little less convenient for terrestrial viewing. There is an erect and right-reading terrestrial finder available as an option if the scope is going to be used mainly for land viewing. An image-erecting eyepiece holder, with a comfortable 45-degree viewing angle, provides terrestrial images that are both upright and correctly oriented left-to-right, so they match what you see with your unaided eyes or binoculars. Flexible cable slow motion controls allow you to manually track action on the ground, as well as planets and deep space objects as they move across the night sky. While the altazimuth mount will not allow motorized tracking or astrophotography, the Celestron Firstscope 102 AZ is a good choice if your primary astronomical interest is purely visual observing of the Moon, planets, and brighter deep space objects at medium to high power. Astronomical observers might want to replace the scope's image-erecting 45-degree eyepiece holder with an optional 90-degree star diagonal. The 90-degree diagonal will give sharper stellar images and more convenient observing near the zenith. The image orientation in the 90 degree diagonal can be confusing in terrestrial observing (images are upright, but backwards), but is not a concern in astronomy.

For more information on Celestron FirstScope 102AZ Telescope #21013 please make sure to check out the Celestron FirstScope 102AZ Telescope Manual in PDF format (~1.53KB).

Specifications for Celestron FirstScope 102AZ Telescope #21013:

Highest Useful Magnification:		200x
Visual Limiting Magnitude:		12.5
Focal Length:		500mm
Focal Ratio:		f/5
Resolution:		1.14 arc seconds
Aperture:		4"
Net Weight:		20 lbs.
Ship Weight:		32 lbs.
Heaviest Single Component:		10 lbs.
Warranty:		2 years

Features of Celestron FirstScope 102AZ Telescope #21013:

• Exquisite optics and precision
• Heavy duty mounts
• Adjustable height aluminum tripod

Package Contents:

• Celestron FirstScope 102AZ Telescope #21013
• 1-1/4" 20mm Plössl (25x) Eyepiece
• 45° Erect Image Diagonal - 1-1/4"
• 6x30 Finderscope
• Altazimuth Mount
• The Sky L1 CD ROM