Handleiding Celestron SkyProdigy 6 - 11076 (pagina 20 van 32) (Engels)

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TELESCOPE BASICS

A telescope is an instrument that collects and focuses light. The

nature of the optical design determines how the light is focused.

Some telescopes, known as refractors, use lenses. Other telescopes,

known as reflectors, use mirrors. SkyProdigy 102 telescope

is a refractor telescope that uses an objective lens to collect its

light. SkyProdigy 6 are reecting telescopes with a primary and

secondary mirror to gather and focus light.

Focusing

Once you have found an object in the telescope, turn the focusing

knob until the image is sharp. To focus on an object that is nearer

than your current target, turn the focusing knob toward the

eyepiece (i.e., so that the focusing tube moves away from the

front of the telescope). For more distant objects, turn the

focusing knob in the opposite direction. To achieve a truly sharp

focus, never look through glass windows or across objects that

produce heat waves, such as asphalt parking lots.

Image Orientation

The image orientation of any telescope changes depending on

how the eyepiece is inserted into the telescope. When observing

through SkyProdigy 102 or 6 using the diagonal, the image will

be right side up, but reversed from left to right. When observing

straight through, with the eyepiece inserted directly into the

telescope, the image will be inverted.

For astronomical viewing, out of focus star images are very diuse,

making them difficult to see. If you turn the focus knob too

quickly, you can go right through focus without seeing the

image. To avoid this problem, your first astronomical target

should be a bright object (like the Moon or a planet) so that the

image is visible even when out of focus.

Calculating Magnication

You can change the power of your telescope just by changing

the eyepiece (ocular). To determine the magnication of your

telescope, simply divide the focal length of the telescope by

the focal length of the eyepiece used. In equation format, the

formula looks like this:

Focal Length of Telescope (mm)

Magnication = ___________________________

Focal Length of Eyepiece (mm)

Let’s say, for example, you are using the 25 mm eyepiece. To

determine the magnication you simply divide the focal length

of your telescope (for example, SkyProdigy 6 has a focal length of

1500 mm) by the focal length of the eyepiece, 25 mm. Dividing

1,500m by 25 yields a magnication of 60 power.

Although the power is variable, each instrument under average

skies has a limit to the highest useful magnication. The general

rule is that 60 power can be used for every inch of aperture.

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Multiplying 4 by 60 gives a maximum useful magnication of

240 power. Although this is the maximum useful magnication,

most observing is done in the range of 20 to 35 power for every

inch of aperture which is 80 to 140 times for SkyProdigy 102 .

Determining Field of View

Determining the eld of view is important if you want to get

an idea of the angular size of the object you are observing. To

calculate the actual eld of view, divide the apparent eld of

the eyepiece (supplied by the eyepiece manufacturer) by the

magnication. In equation format, the formula looks like this:

Apparent Field of Eyepiece

True Field = ________________________________________

Magnication

As you can see, before determining the eld of view, you must

calculate the magnication. Using the example in the previous

section, we can determine the field of view using the same

25 mm eyepiece. The 25 mm eyepiece that comes with the

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by the magnication, which is 60 power. This yields an actual

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To convert degrees to feet at 1,000 yards, which is more useful for

terrestrial observing, simply multiply by 52.5. Continuing with our

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linear eld width of 43.75 feet at a distance of one thousand yards.

The apparent eld of each eyepiece that Celestron manufactures is

found in the Celestron Accessory Catalog (#93685-11).

General Observing Hints

When working with any optical instrument, there are a few

things to remember to ensure you get the best possible image:

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windows is optically imperfect, and as a result, may vary in

thickness from one part of a window to the next. This

inconsistency can and will aect the ability to focus your

telescope. In most cases you will not be able to achieve a

truly sharp image, while in some cases, you may actually see

a double image.

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waves. This includes asphalt parking lots on hot summer

days or building rooftops.

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when viewing terrestrially. The amount of detail seen under

these conditions is greatly reduced. Also, when photographing

under these conditions, the processed lm may come out

a little grainier than normal with lower contrast and

underexposed.

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want to remove them when observing with an eyepiece

attached to the telescope. When using a camera, however,

you should always wear corrective lenses to ensure the

sharpest possible focus. If you have astigmatism, corrective

lenses must be worn at all times.

Inverted image, as viewed with

the eyepiece directly in telescope

Reversed from left to right, as

viewed with a Star Diagonal

Celestron SkyProdigy 6 - 11076 Handleiding

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