Bedienungsanleitung Celestron SkyProdigy 90 - 22091 (Seite 21 von 32) (Englisch)

666995

Zoom out

Zoom in

Vorherige Seite

1/32

Nächste Seite

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 70 telescope is a

refractor telescope that uses an objective lens to collect its light.

SkyProdigy 90 and 130 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 70 or 90 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.

When observing through SkyProdigy 130, a reecting telescope, the

image will be reversed (mirror image) when looking through the

eyepiece.

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 90 has a focal length

of 1250 mm) by the focal length of the eyepiece, 25 mm. Divid-

ing 1250 by 25 yields a magnication of 50 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.

For example, SkyProdigy 90 is 3.5” (90 mm) in diameter.

Multiplying 3.5 by 60 gives a maximum useful magnication of

210 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 70 to 122 times for SkyProdigy 90.

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 has an apparent eld of

view of 50°. Divide the 50° by the magnication, which is 50

power. This yields an actual eld of view of 1°.

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

terrestrial observing, simply multiply by 52.5. Continuing with our

example, multiply the angular eld 1° by 52.5. This produces a linear

eld width of 52.5 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:

• Never look through window glass. Glass found in household

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.

• Never look across or over objects that are producing heat

waves. This includes asphalt parking lots on hot summer

days or building rooftops.

• Hazy skies, fog and mist can also make it dicult to focus

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.

• If you wear corrective lenses (specically glasses), you may

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.

Reversedfromleftto

right,asviewedwitha

StarDiagonal



Invertedimage,as

viewedwiththeeyepiece

directlyintelescope



Inverted image, as viewed with

the eyepiece directly in telescope

Reversed from left to right, as

viewed with a Star Diagonal

Celestron SkyProdigy 90 - 22091 Seite 21

Brauchen Sie Hilfe? Stellen Sie Ihre Frage.

Missbrauch melden von Frage und/oder Antwort

Art des Missbrauchs:

Forenregeln

Neu registrieren

Andere Handbücher von Celestron SkyProdigy 90 - 22091

Das Handbuch wird per E-Mail gesendet. Überprüfen Sie ihre E-Mail.

Ihre Frage wurde zu diesem Forum hinzugefügt

Info