Celestron C90 Instruction Manual - Page 13

Browse online or download pdf Instruction Manual for Telescope Celestron C90. Celestron C90 17 pages. Multipurpose instrument
Also for Celestron C90: User Manual (9 pages), Operating Manual (16 pages)

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All you need to know is when and where to look. Most astronomy publications tell where the

planets can be found in the sky each month.

Observing Deep Sky Objects

Deep sky objects are simply those objects outside the boundaries of our solar system. They include star

clusters, planetary nebulae, diffuse nebulae, double stars, and other galaxies outside our own Milky Way.

Because your spotting scope is not set up for serious astronomical observing, you will need to know where

to look in the sky for these objects. The Celestron Sky Maps (#93722) will help you locate the brightest

deep sky objects.

Once you start observing deep sky objects, there are a few things to remember. First, most deep sky objects

have a large angular size. Therefore, low to moderate power is all you need to see them. Second, visually

they are too faint to reveal any color that is common to photographs. Instead, they have a black and white

appearance. And lastly, because of their low surface brightness, they should be observed from a dark sky

location. Light pollution around large urban areas washes out most nebulae making them difficult, if not

impossible, to see. An LPR (Light Pollution Reduction) Filter (#94126A) is available for use with 1 1 /4"

eyepieces to allow urban use of the C90 for looking at nebulae.

Photographing the Moon

After looking at the night sky for awhile you may want to try photographing it. If you do, start with a nice,

bright object like the Moon. To photograph the Moon:

Attach your spotting scope to a stable platform like the Celestron Photographic Tripod (#93596).

Load your camera with film that has a moderate-to-fast speed (i.e., high ISO rating). Faster films are

more desirable when the Moon is a crescent. When the Moon is full, and at its brightest, slower films

are more desirable. If photographing during the full phase, use a yellow filter to reduce the light

intensity and to increase contrast.

Center the Moon in the field of your spotting scope.

Set the shutter speed to the appropriate setting (see below).

Trip the shutter using a cable release so as not to shake the camera and spotting scope.

Lunar Phase

ISO 50 ISO

Crescent

1/2

Quarter

1/15

Full

1/30

The exposure times listed here should be used as a starting point. Always make exposures that are longer

and shorter than the recommended time. Also, try bracketing your exposures, taking a few photos at each

shutter speed. This will ensure that you will get a good photo.

Keep accurate records of your exposures. This information will be useful if you want to repeat your results

or if you want to submit some of your photos to various magazines for possible publication!

ISO

ISO 400

100

200

1/4

1/8

1/15

1/30

1/60

1/125

1/60

1/125