ASTRO-PHYSICS 400 Handmatig - Pagina 8

Blader online of download pdf Handmatig voor {categorie_naam} ASTRO-PHYSICS 400. ASTRO-PHYSICS 400 8 pagina's. German equatorial mount with dual axis quartz drive (silver-dome knobs)

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GUIDING YOUR ASTROPHOTOS

The natural tendency of astrophotographers is to push the directional button of the controller in the direction he or she

wants the guide star to move until the star has centered itself in the guiding reticle. This method often results in

overshooting the center of the reticle since the reaction time to let go of the button is often too late. By the time the

gears in the drive motor have reversed and are driving again at the normal guiding rate, the star has moved past the

center of the reticle. Then the opposite button is pushed to move the guide star back in the opposite direction toward

the center and the same overshooting may occur.

The proper way to guide (and this will apply to almost any commercially available mounting) is to pulse your correction,

much as the SBIG ST-4 does in its auto-guiding operation. Pulse the button for only a fraction of a second and note the

new position of the guide star. If it has not moved far enough, pulse it again. Normally, it takes only one or two pulses

to re-center the star in declination, since this drift will be extremely slow (assuming the mount was properly polar

aligned). When the star needs to be reversed, it rarely takes more than 5 to 8 pulses in rapid succession, each lasting

less than 1/10 second to get the star to re-center in the reticle. This same method should be used to keep the star

centered in right ascension also. With some practice, you will be able to keep the guide star centered perfectly in

declination with only an occasional pulse every 5 to 10 minutes while concentrating almost entirely on the right

ascension drift.

MOUNT MAINTENANCE AND ALIGNMENT

Under normal operating conditions, no maintenance is required. Your 400 mount is a precision instrument with very

accurate worm and wheel adjustments. Please be careful if you place the mount on a flat surface, i.e. the ground or

trunk of your car. The gear alignment may be affected if the knobs sustain undue lateral force. This is true of any fine

instrument. We suggest that you transport and store the mount in a case or in a well-padded box

NOTE: If your battery runs low, the declination motors will stop first, though the R.A. will continue to drive until

the power is drained.

If any problems occur, please don't hesitate to contact Astro-Physics for assistance.

Recommended reading list from our staff:

The Backyard Astronomer's Guide, Terence Dickinson and Alan Dyer, Camden House Publishing, 1991. The authors,

both former editors of Astronomy magazine, offer practical insight into astronomical equipment, finding your way around

the sky, polar alignment, using setting circles, and astrophotography. This book provides excellent explanations and is

well organized and illustrated.

01-22-94

ASTRO-PHYSICS INC

11250 Forest Hills Road

Rockford, IL 61115

Telephone: (815) 282-1513

Fax: (815) 282-9847