INSTRUCTION MANUAL MO D#93648LE OFF-AXIS GUIDER. PARTS LIST Off-Axis Guider SCT Adapter. Please see the Celestron website for detailed warranty. The Off-Axis Guider is an essential astroimaging accessory for long focal length telescopes that require the most accurate guiding possible. The Celestron Off-Axis. The Radial Guider is compatible with Celestron’s C5, C6, C8, C9¼, C11 and C14 telescopes and comes with a unique prism angle adjustment screw. Deluxe Off-Axis Guider #5521 instructiOn MAnuAl. Unlock the radial adjustment lock thumbscrew and slowly rotate the autoguider until you see a guide star.
Off Axis Guiders for Telescopes at Astronomics. Lunar and planetary photos involve short exposure times – from a brief 1/1. CCD image to as much as 8 seconds for a 3. With such short exposures, most telescopes have a drive more than accurate enough to provide sharp photos. However, when you aim your telescope outside the solar system – at nebulas, star clusters, and galaxies – photographic exposure times increase dramatically .
The best telescope drive (even one with a periodic error correction circuit to reduce recurring drive errors) can’t compensate for random atmospheric refraction or non- periodic drive errors. Some corrections to the telescope drive speed and declination still have to be made manually to keep the stars from turning into streaks on your film or CCD image. Making those corrections is the job of the drive corrector typically built into your telescope’s drive system. However, you still have to decide when those corrections should be made, so you can push the right buttons to tell your drive corrector to do its thing.
Celestron 93648 : This Celestron off-axis guider is designed for use with long focal length scopes.
Celestron Radial Guider Manual Transfer
Celestron 93517 Pdf User Manuals. View online or download Celestron 93517 Instruction Manual. Keep things lined up correctly with off-axis guiders. Buy off-axis guiders, CCD & photographic equipment, and telescopes at Astronomics.
Buy Celestron Off-Axis Guider features Adjustable 12.5mm Prism, Fixed-Orientation Helical Focuser. Review Celestron Astrophotography, Accessories. Find helpful customer reviews and review ratings for Celestron Radial Guider Schmidt-Cassegrains at Amazon.com. Read honest and unbiased product reviews from our users./>.
Celestron Radial Guider Manual Meat
Telling you when is the job of the off- axis guider or photoguide telescope (which have their own separate category in Photographic Accessories). An off- axis guider is a T- shaped camera mount. One short arm of the T threads onto the rear cell of Schmidt- Cassegrains or slips into refractor or reflector focusers. Your 3. 5mm camera is attached to the other short arm by means of a T- ring (most CCD cameras have built- in T- threads and don’t need a T- ring).
An illuminated reticle eyepiece (which also have their own separate category in Photographic Accessories) is inserted into the eyepiece holder that forms the long third arm of the guider. Light passes through the guider and falls onto the film in your camera or onto the CCD chip.
However, the light of a guide star (from the edge of the telescope’s circular field, and not from the rectangular area in the center that you are photographing) is diverted to the crosshairs of an illuminated reticle eyepiece by a small off- axis prism within the guider body. Any motion of the guide star relative to the crosshairs immediately shows drive train or refraction errors. This allows you to use the drive corrector to correct the errors before they become large enough to show as streaked star images on your photos. The off- axis guider allows you to guide your telescope through the same optics that are taking the picture. This eliminates any possibility of guiding error if you carefully keep the guide star centered under the eyepiece crosshairs. But careful attention must be paid to your guiding.
A guide star that drifts only 5/1. Schmidt- Cassegrain will give you star trails 1/3” long on a 5” x 7” print. That’s a guiding error that is clearly visible, to say the least! For a more detailed discussion of how much guiding error can be tolerated in photographs, see this website’s section on illuminated reticle eyepieces. Focusing your camera on the deep space object to be photographed is done through your camera before a guide star is located. If your subject is faint, focus on a nearby bright star. With Schmidt- Cassegrain telescopes, it is often advisable to turn the focus knob slightly counterclockwise (1/1.
Without touching the main telescope focus knob, look through the illuminated reticle eyepiece and bring the stars in it into focus by moving the eyepiece up and down within the eyepiece holder tube. Lock in the eyepiece’s best focus by tightening the thumbscrew on the eyepiece holder. A focus ring on the eyepiece allows you to bring the eyepiece crosshairs into sharp focus separately before focusing on the stars.
Rotate the guiding eyepiece holder around the edge of the field being photographed (and in some cases radially adjust it into and out of the field) until you find a suitably bright guide star. This is usually the most time- consuming and frustrating part of deep space photography, as the coma of reflector telescopes and the field curvature of Schmidt- Cassegrains can smear the light of guide stars into dim and out- of- focus blurs that are difficult to see. A bright guide star is typically thrown slightly out of focus and the resulting enlarged stellar image is centered under the crosshairs of your guiding eyepiece. If the only convenient guide star is relatively dim, it’s better to keep the star sharply focused (so that it appears brighter) and position it at the intersection of the eyepiece crosshairs, rather than under the crosshairs. To make it easy to determine in what direction the guide star drifts during a photo, temporarily turn off your telescope’s drive before you start photography and rotate your eyepiece crosshairs until the guide star’s drift is parallel to one crosshair. After starting up your drive again, movement along this crosshair will show drive errors in right ascension. Movement at right angles towards or away from this crosshair will show errors in declination – from imprecise polar alignment or atmospheric refraction, for example.
If you have a variable rate drive corrector, it is usually more effective to set the speed a trifle slow, rather than exactly on speed. In this way, right ascension corrections will usually only require an occasional touch on the ‘fast’ button, rather than a series of alternating ‘fast’ and ‘slow’ corrections. As a general rule, for casual astrophotography, your illuminated reticle should have a minimum magnification of at least 2x per inch of main telescope focal length.
An 8. 0” focal length scope, such as an 8” f/1. Schmidt- Cassegrain, would require a minimum guiding magnification of 1. For photos taken for publication, or if slides or large prints (8” x 1.
Schmidt- Cassegrain). With all off- axis guiders, a Barlow lens can be used to increase the magnification of the illuminated reticle eyepiece to the required power. As a general rule of thumb, if you can’t see the chosen guide star through a 6 x 3.