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12.5” Classical Cassegrain Astrograph
The OMI 12.5” Classical Cassegrain Astrograph was designed from the ground up to meet the rigid demands of high end astrophotography.
- Ideal for use with large format CCD sensors
- Very flat field without the use of correctors
- Carbon fiber truss system to maintain consistent focus
- Ample back focus to accommodate long image trains
- Supports industry standard accessories
$12,999 - includes robotic focuser, cooling system, dew control, mounting plate, piggyback dovetail plate, mirror protectors and all required cables.
$14,999 - includes above accessories and 3” Optec Pyxis rotator and 3” Astrodon Monster Moag off-axis guider
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- 12.5” Aperture
- F12 Focal Ratio
- Optional F9 Reducer
- 8.5” Usable Back-focus
- Knife Edge Baffles
- Robotic Secondary Focusing
- Primary Cooling System
- Carbon Fiber Truss System
- Low Thermal Dynamics
- Easy Collimation Process
- 27 Pounds Total Weight
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FEATURES:
Classic Cassegrain Optics
The Cassegrain (sometimes called the "Classic Cassegrain") has a parabolic primary mirror, and a hyperbolic secondary mirror that reflects the light back down through a hole in the primary. Folding the optics makes this a compact design.
With the absence of glass correctors or optical contact lenses, the OMI Cassegrain optical design eliminates chromatic aberrations and reduces coma and off-axis aberrations with large format CCD cameras.
Optical Mechanics has been producing Cassegrain optics for over 15 years to some of the world’s most respected telescope manufactures ensuring that your OMI 12.5” CC AS will provide the best optical performance possible. |
8.5” OF USABLE BACK-FOCUS
Having ample back-focus ensures that you have enough room for the most demanding astrophotography setups.
With 8.5” of usable back-focus, the OMI 12.5” Classical Cassegrain allows for the concurrent use of rotators, off-axis guiders, filters wheels, reducers and any format CCD camera. In addition, the rear cell provides a standard 3” Celestron male thread and AP 2.7” female thread for maximum compatibility with off the shelf accessories.
Motorized secondary focusing eliminates the need to further extend your back-focus and introduce flexure into your image train. |
FLAT FIELD, NO OFF AXIS LIGHT
An f/4 primary mirror and a oversized 4X secondary mirror complete with knife edged, flocked baffles produces an extremely flat field on the largest of CCD Cameras.
With the emergence of larger format CCD sensors, OMI has designed a telescope from the ground up to take advantage of the entire CCD sensor from corner to corner, keep stars consistent across the entire field of view.
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THERMAL STABILITY
Thermal stability is maintained through the use of carbon fiber trusses. The carbon fiber tubes used for the trusses are not only strong but have a near zero coefficient of expansion along their length. This, along with a reasonable depth of field, keeps the focus position from drifting over a period of hours as the ambient temperature changes during observation.
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EASY COLLIMATION
Collimation for both the Primary and secondary mirrors are completed in similar manner. Both mirrors are adjusted by turning 4 screws. This allows for a very intuitive method of adjustment. The secondary mirror is also center marked to aid in alignment.
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ROBOTIC FOCUSING
Focus is achieved through axial motion of the secondary mirror. The secondary moves on a shaft of hardened steel captured between 5 bearings to eliminate any image wobble. This motion is controlled by a Robofocus motor. The focus is adjustable by using a hand paddle.
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LIGHTWEIGHT FRAME
The OMI 12.5" Classical Cassegrain uses aluminum construction combined with carbon fiber trusses to produce a very stiff yet light weight system. The OTA including optics and focus motor weighs in at 27 pounds excluding additional equipment.
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