Astro-Tech Focuser collimating ring for 10" through 16" Astro-Tech Ritchey-Chrétiens

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This Astro-Tech FCR1012 focuser collimation ring lets you fine-tune the focuser collimation of 10" through 16" Astro-Tech Ritchey-Chrétien astrographs to improve the sharpness at the corners of images taken with large 35mm-class DSLR and CCD sensors.
Our Product #: FCR1012
Astro-Tech Product #: FCR1012

Product Description

This Astro-Tech FCR1012 focuser collimation ring is an economical and very useful addition to the imaging train of solid-tube (bot aluminum and carbon fiber) Astro-Tech 10" through 12" Ritchey-Chrétien astrographs to improve your image sharpness when imaging with DSLRs and CCDs that use large format 35mm-class CCD sensors.

The focuser on solid-tube 10" through 16" Astro-Tech Ritchey-Chrétien astrographs threads directly onto the rear plate of the telescope. Machining tolerances in the various components can sometimes lead to a very minor tilt in the alignment of the focuser and camera in relation to the scope's separate optical path. This is rarely visible in images taken with an APS-C size imaging sensor (up to an approximately 23mm diagonal). 

However, with large format 35mm-class DSLR and CCD sensors, image sharpness in the corners of your images will be improved if your camera is precisely aligned with the scope's optical path.

This focuser collimation ring allows you to do just such a precise alignment, by letting you separately align your focuser/camera combination to the scope's optical path completely independently of the baffle tube/primary mirror alignment.

The focuser collimation ring consists of two spring-loaded rings with push/pull collimating screws that let you tilt the rings slightly in relation to each other and then lock them firmly in place. The collimation ring fits between your scope's rear cell and your focuser/camera combination. Once installed, you can then adjust the tilt of the collimation ring to zero out any tilt in your focuser during final scope collimation.

The telescope side of the collimation ring has M117 x 1 female threads that connect to the rear cell of your scope (or to any 117mm extension rings you have attached to the rear cell to provide the proper scope to camera spacing). The camera side of the collimation ring has M117 x 1 male threads for attaching your focuser. The collimation ring takes up only 15mm of back focus. 

This focuser collimating ring is already built into the rear cells of all truss-tube Astro-Tech R-Cs.

Tech Details

Weight 5 oz.
Warranty 2 years


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