Fully multicoated, air-spaced achromatic doublet objective lens with smooth helical focus Using the included parfocal ring on the autoguider or CCD camera nosepiece provides some more focusing flexibility, and it also allows you to repeat the autoguiding setup between different imaging sessions. The CCD will not rotate during focus adjustments. The camera-end of the 1.25" eyepiece holder also features a short male T / T2 thread (M42x0.75) on the outside.įocusing is achieved by turning the helical focuser ring at the rear of the scope. Couple this package with a main scope and a 1.25" autoguider CCD, and you will be ready to experience a new level of accuracy that autoguiding brings to long exposure astrophotography - without the bulk and expense of a larger dedicated guide scopes that were formerly required. Simply insert the 1.25" nosepiece of your CCD camera and tighten. The 1.25" autoguider receptacle features three locking thumbscrews for a secure fit. As a result, it is possible that this bracket may not fit into other bases and some filing/adaptation may be required. However, please note that although this base has a standard Vixen/Synta style design, there is no standard defined size for this design.
The bracket should also fit directly into the Synta/Vixen style finder bases already found on many telescopes, without the need for the included mounting plate/base (although these are also provided should the need arise). In addition to an optical tube with a helical focuser, this package includes an adjustable finder bracket, a universal dovetail mounting base, as well as an adapter plate to allow you to easily mount this guide scope on a variety of telescopes in various configurations. The helical focuser ring is ribbed to improve grip and a thumbscrew locks the focuser in place once best focus is achieved. The helical focuser has a 12.5mm travel range and is designed to produce zero backlash. This ensures that the guide star field stays fixed while focus adjustments are made.
The focuser moves the autoguider in or out while maintaining its orientation relative to the light path. The helical focuser on the StarGuider II retains a fixed orientation so that your CCD autoguider will not rotate during focus adjustments. All internal surfaces of the tube are painted a flat black to improve contrast. Its 162mm (f/3.2) short focal length design provides a bright, wide field which aids in the location of suitable guide stars. The StarGuider II features a 50mm fully-multicoated achromatic doublet objective. And the price of this accessory will add little strain to your astrophotography budget. A guidescope is a must for accurate astrophotography exposures even with high precision mounts. Its light weight adds very little to your autoguiding setup thus putting less strain on your mount's tracking mechanism, allowing for smoother guiding.
It is an excellent accessory for telescopes with a focal length of up to 1500mm, and is perfectly suited for use with small-chip CCD autoguiders. With the availability of computers and sensitive digital cameras, guiding is now accomplished automatically.Agena's compact 50mm StarGuider II Mini Guide Scope with Helical Focuser package will be just the ticket for your long exposure astrophotography autoguiding needs.
In the earliest days of imaging in the late 19th century until the 1990s, amateur astronomers guided manually by visually tracking a guide star over the course of a long exposure and nudging the mount mechanically or electrically back onto the right path. During the length of the exposure, the astro-imager follows the motion of a star-the guide star-and, when the star appears to move slightly because of errant motion of the mount, applies a corrective signal to the mount to move the star back to its original position. Autoguiding, or guiding in general, involves the application of small corrections to the position of an equatorial mount during long-exposure imaging. Color Correction & Minus Violet Filtersįigure 1 – Tracking errors during an image of the globular cluster M15 (Credit: Brian Ventrudo).Correctors, Focal Reducers & Flatteners.
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