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exposure. f/5 is faster than f/10. The faster the ratio, the faster exposure time is needed when a camera is hooked up to the telescope. Your telescope has slower focal ratio at f/8.8. Sometimes, astronomers use focal reducers to make slow exposure telescopes have faster focal ratios.
USE THE SPECIFICATIONS TO CALCULATE THE MAGNIFICATION OF YOUR EYEPIECE
The power of a telescope is how much it magnifies objects. Your 25mm eyepiece magnifies an object 28 times. Your 9mm eyepiece magnifies objects 78 times.
But if you obtain other eyepieces, you can calculate how much magnification they have with your telescope. Just divide the focal length of the telescope by the focal length of the eyepiece.
Focal Length of the Telescope
÷
Focal Length of the Eyepiece
=
Magnification
Look at the specifications. You will see that the focal length of your scope is 1000mm. Let’s say that you have obtained a 13mm eyepiece. You can tell that what the focal length of your eyepiece is as it is always printed on the side of an eyepiece. Divide: 1000 ÷ 13, which equals 76.9. Round this off to the nearest whole number and your new eyepiece magnifies objects 77 times.
If you use a Barlow lens with one of your eyepieces, it doubles the magnification of your eyepiece. Other types of Barlows can triple or further increase the power of an eyepiece. To find out how much your magnification is when you use a Barlow, multiply your eyepiece’s magnification by two.
Your 25mm
Eyepiece’s magnification x 2
=
Magnification with a 2X Barlow lens
It’s worth repeating: Keep in mind that a bright, clear, but smaller image is
more interesting than a larger, 15 dimmer, fuzzy one. Using too high a power eyepiece is one of the most common mistakes made by new astronomers. So don’t think that higher magnification is necessarily
TAKING CARE OF YOUR TELESCOPE
Your telescope is a precision optical instrument designed for a lifetime of rewarding viewing. It will rarely, if ever, require factory servicing or maintenance. Follow these guidelines to keep your telescope in the best condition:
•As with any quality instrument, lens or mirror surfaces should be cleaned as infrequently as possible. Front surface aluminized mirrors, in particular, should be cleaned only when absolutely necessary. In all cases avoid touching any mirror surface. A little dust on the surface of a mirror or lens causes negligible loss of performance and
Looking at or near the Sun will cause irreversible damage to your eye. Do not point this telescope at or near the Sun. Do not look through the telescope as it is moving.
