Celestron Off-Axis Guider
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 Guider uses a prism to intercept a small portion of the telescope’s focal plane (outside the field of view of the main imaging camera) to locate a guide star. Any movement seen by the guide star will be the exact same movement seen by the imaging camera. Guiding this way will correct for tracking errors, as well as opto-mechanical errors or flexure. The result: better astroimages with pinpoint round stars.
Off-Axis Guiders have been around for a long time, but typically pose three main challenges:
- Finding a guide star from the far edges of the telescope’s focal plane can be difficult, considering the small field of view and sometimes less-than-ideal illumination.
- Getting both imaging camera and autoguider to reach focus with one another is time consuming and sometimes requires experimentation.
- Additional spacers and adapters are usually required for your particular camera, telescope, and autoguider, which adds to cost and complexity.
Celestron's Off-Axis Guider addresses these challenges by:
- Providing a large 12.5mm prism that can be adjusted to move closer to the center of the telescope’s focal plane, depending on the size of the imaging camera. This results in brighter guide stars, with the help of the large prism to fully illuminate the autoguider sensor.
- Featuring a high-quality, fixed-orientation Helical focuser. This provides extremely smooth and accurate focus of the autoguider without changing (or twisting) the autoguider camera orientation.
- All the needed spacers and adapters are included for most common imaging configurations, including DSLR cameras, Nightscape CCD cameras, and more. The following adapters are included: SCT/EdgeHD, female M48, female M42 (T-thread), male M48, male M42 (T-thread), 3 T-thread adapters.
Celestron Off-Axis Guider Specifications
- Weight: 18 oz.
- Clear Aperture: 48mm
- Helical Focuser Travel: 8mm
- Telescope Connection: M42 T-thread, M48, and SCT/EdgeHD
- Autoguider Connection: M42 T-thread, and standard 1.25" adapter
- Camera Connection: M42 T-thread, and M48
Celestron Product Number: 93648
- Additional Information
SKU CE-93648 UPC Code 050234936484 Manufacturer Celestron Warranty 2 Year Warranty
- Included Items
- Celestron Off-Axis Guider
- Questions & Answers
Product QuestionsQuestion by: Stevekirk on Nov 20, 2014 11:08:24 AMUnfortunately, this OAG will not have correct spacing from the SCT f/6.3 reducer corrector as it is disigned for the EdgeHD scopes with their longer back focus numbers. It will work with the f/7 reducer correctors for the 11" and 14" EdgeHD scopes.Answer by: Chris (Admin) on Nov 21, 2014 11:59:53 AMTwo quick questions: can I use this OAG with (1) my 8-inch Celestron C/S (part of Nexstar Evolution) in combination with the F/6.3 focal reducer, and (2) with my Astro-Tech refractor? Thanks.Question by: Jim K on Oct 13, 2016 2:35:00 PMThe answer to first part of your question is maybe, The optimum back focus of a .63 reduced is 105mm. The SCT Adaper that would attach to the reducer 25.3mm, the OAG Body is 29mm and the Male M42 and M48 camera adapters: 12.5mm. That only leave 38.2mm of back focus remaining to adapt a camera. If your camera takes up less than 38.2mm then, you should be fine using this with the .63 reducer.
Since most Astrotech flatteners have a back focus of 55mmm, it is unlikely that this OAG will work for your refactor.
If you are looking for something that will fit both telescope systems, please give us a call at 1-800/483-6287 or email us at firstname.lastname@example.org. There are many other solutions out there that give you the best of both worlds.Answer by: Jonathan Cheek (Admin) on Oct 29, 2016 1:07:00 PMQuestion by: JimAstro on Dec 24, 2014 9:31:43 AMThere are a good number of different ways this can be done, but let's go with the most direct. The Celestron SCT Visual-Back will connect to the camera-side SCT-thread adapter that is included with the OAG. It presents a 1.25" nosepiece receiver.
http://www.optcorp.com/celestron-visual-back-for-sct-refractors.htmlAnswer by: Eric_B (Admin) on Dec 26, 2014 5:22:44 AM
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