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The Ambassador 50AZ model has a fixed eyepiece which has a magnification (power) of 16x. This model
was designed for terrestrial observing and this power is good for all around general usage.
The Ambassador 80AZ model comes standard with a 25mm eyepiece which has a magnification (power)
of 32x. You can purchase optional eyepieces (not with a brass finish) to give you higher or lower powers.
You can see what is available by looking on the Celestron website.
You can change the power of your 80mm telescope just by changing the eyepiece (ocular). To determine
the magnification 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)
Magnification = ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
Focal Length of Eyepiece (mm)
Let’s say, for example, you are using the 25mm eyepiece that came with your telescope. To determine the
magnification you divide the focal length of your telescope (the Ambassador 80AZ for this example has a
focal length of 800mm) by the focal length of the eyepiece, 25mm. Dividing 800 by 25 yields a
magnification of 32x.
Although the power is variable, each instrument under average skies has a limit to the highest useful
magnification. The general rule is that 60 power can be used for every inch of aperture. For example, the
Ambassador 80AZ is 3.2 inches in diameter. Multiplying 3.1 by 60 gives a maximum useful magnification
of 186 power. Although this is the maximum useful magnification, most observing is done at low power.
Note on Using High Powers – Higher powers are used mainly for lunar and sometimes planetary observing
where you can greatly enlarge the image, but remember that the contrast and brightness will be very low due
to the high magnification. For the brightest images with the highest contrast levels, use lower powers.
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When using 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 affect 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 difficult to focus when viewing terrestrially. The amount
of detail seen under these conditions is greatly reduced.
• If you wear corrective lenses (specifically glasses), you may want to remove them when observing
with an eyepiece attached to the telescope. If you have astigmatism, corrective lenses must be worn
at all times.
