Meade 12.5 Seeing Conditions, Observing Guidelines, Care Of Optics And Main Tube

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detail than a dimmer, poorly resolved, larger image.

Because of certain characteristics of the human eye (in particular, eye pupil diameter) and because of optical considerations inherent in the design of the telescope, there exist minimum practical power levels also. Generally speaking the lowest usable power is approximately 4X per inch of telescope aperture.

SEEING CONDITIONS

Even in normal city conditions, with all of the related air and light pollution, there are many interesting celestial objects to observe. But, to be sure, there is no substitute for the clear, dark, steady skies generally found only away from urban environments, or on mountaintops: objects previously viewed only in the city take on added detail or are seen in wider extension, or even become visible at all for the first time.

The amateur astronomer is faced typically with two broadly defined problems when viewing astronomical objects through the Earth’s atmosphere: first is the clarity, or transparency, of the air, and secondly the steadiness of the air. This latter characteristic is often referred to as the quality of “seeing.” Amateur astronomers talk almost constantly about the “seeing conditions,” since, perhaps ironically, even the clearest, darkest skies may be almost worthless for serious observations if the air is not steady. This steadiness of the atmosphere is most readily gauged by observing the “twinkling” of the stars: rapid twinkling implies air motion in the Earth’s atmosphere, and under these conditions, resolution of fine detail (on the surface of Jupiter, for instance) will generally be limited. When the air is steady, stars appear to the naked eye as untwinkling points of unchanging brightness, and it is in such a situation that the full potential of the telescope may be realized: higher powers may be used to advantage, closer double stars resolved as distinct points, and fine detail observed on the Moon and planets.

OBSERVING GUIDELINES

Several basic guidelines should be followed for best results in using your telescope:

1.Try not to touch the eyepiece while observing. Any vibrations resulting from such contact will immediately cause the image to move.

2.Allow your eyes to become “dark-adapted” prior to making serious observations. Night adaptation generally requires about 10-15 minutes for most people.

3.Let the telescope “cool down” to the outside environmental temperature before making observations. Differences in temperature between a warm house and the cold outside air require about 30 minutes for the telescope’s optics to regain their true correct figures. During this period the telescope will not perform well.

4.If you wear glasses and do not suffer from astigmatism, take your glasses off when observing through the telescope. You can re-focus the image to suit your own eyes. Observers with astigmatism, however, should keep their glasses on, especially with lower powered eyepieces. The effects of astigmatism are reduced with higher power eyepieces, so eyeglasses may be removed to improve eye relief.

5.Avoid setting up the telescope inside a room and observing through an open window (or, worse yet, through a closed window!). The air currents caused by inside/outside temperature differences will make quality observing impossible.

6.Perhaps most important of all, avoid “overpowering” your telescope. The maximum usable magnification at any given time is governed by the seeing conditions. If the telescopic image starts to become fuzzy as you increase in power, drop down to a reduced magnification. A smaller, but brighter and sharper, image is far more preferable to a larger, but fuzzy, indistinct one.

As you use your telescope more and more, you will find that you are seeing more and finer detail: observing through a large-aperture telescope is an acquired skill. Celestial observing will become increasingly rewarding as your eye becomes better trained to the detection of subtle nuances of resolution.

CARE OF OPTICS AND MAIN TUBE

With the reasonable care due any fine instrument, your Meade telescope will last a lifetime. If the eyepieces become dirty, try cleaning them with a camel’s hair brush or compressed air. If you must wipe the surface of the lenses, do so gently with a soft cloth so as not to scratch the protective coatings.

The aluminum coating on the primary and secondary mirrors may last more than ten years without significant deterioration. (The coatings will last a shorter period if regularly exposed to salty or polluted air.) Minor blemishes, scratches, or streaks will NOT impair the telescope’s performance. Re-coating, when necessary, is relatively inexpensive. Contact your local Meade dealer for information on mirror re-coating services.

The most common error is to clean the optics too often. If cleaning does become necessary, clean as follows:

1.Using distilled water and cotton, gently swab the surface of the mirror to remove any dust or dirt. Use the cotton to make one pass over the mirror and then use new cotton. This will keep the dirt previously removed from contacting the mirror surface and scratching the coatings.

2.Dip a wad of cotton in a mild detergent solution (1/2 teaspoon to 1 pint of water) and gently swab the entire surface. This will remove any oily deposits or fingerprints.

3.Swab the entire surface. Do not turn over the cotton wads or dissolved skin oils may deposit on the mirror’s surface. Immediately take a dry swab and continue wiping the entire surface gently. Keep changing wads until the mirror surface is completely dry and free of streaks.

When cleaning the outside of the Starfinder optical tube (1), use a mild detergent, (Pine-Sol, Formula 409, Fantastic, or oil soap). Oil soap is preferred as it also acts as a preservative for the paint. Solvent or alcohol-based cleaning solutions will diminish the original luster of the paint.

OPTIONAL ACCESSORIES

A wide assortment of professional Meade accessories is available for the Starfinder telescopes.

Dust Covers: Snug-fitting vinyl dust covers protect optics from outside dust during storage of the telescope.

Eyepieces: Many additional eyepieces are available for higher and lower magnifications. All Meade Starfinder Equatorial telescopes accept standard 1.25" O.D. eyepieces as well as 2" O.D. eyepieces.

Meade Super Plössl (SP), Super Wide Angle (SWA), and Ultra Wide Angle (UWA) Eyepieces in the standard American-size (1.25") barrel diameter permit a wide range of magnifying powers with the telescope. Powers obtained with each eyepiece are as follows: