1. What will the telescope be used for? Astronomical observing? Terrestrial observing? Both?
If the telescope is a first-time purchase, most people want to observe the entire range of astronomical and terrestrial subjects. Refracting telescopes and mirror-lens telescopes (ETX90 AT-TC and ETX125 AT-TC) are generally more versatile in a wide array of land and astronomical applications. If your applications in land-viewing and astronomy are about of equal importance, then one of these models will probably be the instrument of choice.
Alternatively, if your interests run more strongly to astronomy as a field of study, then reflecting telescopes (Meade Models DS2114 AT-TC and DS2080 AT –TC) or mirror-lens telescopes such as the Meade ETX Series are ideal. Reflecting telescopes usually represent the largest telescope aperature available per dollar of cost. Mirror-lens telescopes are the most versatile of all optical designs: it is this versatility, combined with uncompromised image resolution and portability, that have made the Meade ETX90 AT-TC and other Meade mirror-lens models the most popular telescopes in the world among serious observers.
2. How serious are my intended applications?
Many advanced amateur astronomers began the study of astronomy with a 70mm refractor. The Meade 70mm-diameter telescope NG70-SM are perfectly suited for a person at an introductory level of interest. But if one's interests are maintained, he or she may want a larger telescope, such as the Meade ETX series or DS2080 AT-TC. Larger Meade telescopes enable the study of much greater detail in all observed celestial objects,
3. What is the size of my budget?
Meade Instruments manufactures only high-resolution telescopes, instruments designed for a lifetime of clear, sharp, high-performance imaging, irrespective of a telescope's price level. However, if your budget permits, consider the advantages of larger telescope diameters; try to buy a telescope you won't quickly outgrow. The NG70-SM is a fine beginning telescope, but the Model DS2114 AT-TC collects more than three times as much light for a relatively modest additional expenditure. The Model DS2080 AT-TC yields an impressive level of observable detail, but the Meade ETX90 AT-TC Telescope, at only a slightly higher price, allows for unprecedented portability.
The Meade NG70-SM and 114 EQ-ASTR offer excellent value for the beginner and each are capable of producing sharp, clear images of all the major planets and astronomical phenomena. The altazimuth mount provides smooth tracking in both altitude (vertical) and azimuth (horizontal) directions. Larger refractors, such as the ETX80 AT-TC, 90AZ – ADR and DS2080 AT-TC, permit observation of a wide range of additional objects in greater resolution and detail while the ETX90 AT-TC and ETX125 AT-TC offer unprecedented optical resolution and performance for a much broader range of astronomical study.
Land and Sky Viewing:
If you are equally interested in both land and sky viewing, note that many astronomical models may also be used for terrestrial observing. Refracting telescopes such as NG70-SM, 90AZ – ADR, ETX80 AT-TC and DS2080 AT-TC are well suited to land observations because of their convenient image orientation and location, while the ETX90 AT-TC and ETX125 AT-TC Astronomical Telescopes perform magnificently as either land or sky instruments and have the advantage of compactness for use in the field.
The Importance of Computerized Tracking and Object-Location
Observing an astronomical object involves following a constantly moving target. Every object in the sky moves in the same manner as our Sun, rising in the East and setting in the West. This apparent celestial movement is caused by the rotation of the Earth.
Computerized Tracking: To the unaided eye an object like the Moon appears to move slowly across the sky, but will, in fact, move surprisingly quickly through the field of view of a telescope. The AutoStar®Computer Control System directs the telescope to automatically follow fast-moving celestial objects.
Automatic object-location: A novice astronomer often spends a disproportionate amount of time learning the sky and searching for subjects to view. AutoStar technology solves this learning curve. Meade’s revolutionary AutoStar Computer Control System facilitates automatic object-location and tracking of over 1400 objects. Computer Controlled Telescopes include:
The purpose of these statements is not to press the unitiated into purchasing more telescope than required for the user's intended applications. But a little study before purchase can pay important rewards in long-term satisfaction with the telescope's full range of capabilities. Listed within the discussion of each telescope series throughout the Meade website is a description of what you can see through each telescope model. These descriptions, in conjunction with a model's price level, permit a useful balancing of budgetary and performance characteristics.
How to Calculate Power
How to Calculate Power: The magnification, or power, at which a telescope is operating is a function of the focal length of the telescope's main (objective) lens (or primary mirror) and the focal length of the eyepiece employed.
The focal length of the objective lens is the distance between the lens and the point at which it brings light rays to a focus; this focal length (in milimeters, or mm) is printed on a label affixed to the optical tube of every Meade telescope. The focal length of each eyepiece (which typically ranges from 4mm to about 40mm) is printed on the upper surface of the eyepiece. To calculate power, divide the focal length of the eyepiece into the focal length of the objective lens.
Example: The Meade DS2080 AT-TC telescope has an objective lens focal length of 800mm; when this telescope is used with a 25mm eyepiece, a power of 800/25 = 32 power (written as "32x") results.
A Word about "Power": When buying a telescope one of the least important factors to consider is the power, or magnification, of the instrument. The key to observing fine detail, whether on the surface of the Moon or on a license plate one mile in the distance, is not power, but aperture - i.e., the diameter of the telescope's main (objective) lens or primary mirror. The power at which a telescope is operating is determined by the eyepiece employed; all Meade telescopes include one or more eyepieces as standard equipment, and optional eyepieces are available for higher or lower powers. Within reason power is useful, [but the most common mistake of the beginning observer is to "overpower" the telescope and to use magnifications which the telescope's aperture and typical atmospheric conditions can not reasonably support.] The result is an image which is fuzzy, ill-defined, and poorly resolved, through no fault of the telescope. Keep in mind that a smaller, lower-power, but brighter and well-resolved, image is far superior to a large, high-power, but dim and poorlyresolved, one.