The Celestron RASA 11" Rowe-Ackermann Schmidt Astrograph is an incredibly fast f/2.2 optical system designed for imaging with modern CMOS cameras. The RASA 11" provides a flat field free of optical aberrations across a 43.3mm field of view, with usable performance up to 52mm making it suitable for full frame sensors. As the RASA 11" is a fast f/2.2 system, you can use much shorter exposure times than usual to capture faint objects. This combined with the 620mm focal length means that you don't need to have super-accurate tracking over extended periods, making the RASA 11" suitable for use on a wide variety of higher capacity equatorial mounts. The RASA 11" includes Celestron's Ultra-Stable Focus System which utilizes two sets of precision sealed ball bearings to virtually eliminate lateral movement of the primary mirror when focusing, slewing or tracking. An additional top-mounted CGE dovetail allows you to easily mount accessories such as Eagle computers or guide scopes. Building on the legacy of Celestron's Schmidt Cameras of the 1970's, the RASA 11" allows astrophotographers to capture incredible data with minimal exposure times. The 4-element lens group with rare-earth ED glass provide images free from aberrations that are inherent in other types of telescopes. The RASA 11" performs best once its optics have reached thermal equilibrium with the ambient air. To aid this, the telescope is equipped with cooling fans which direct air through the tube and around the primary mirror. Note: The RASA 11" is designed for astrophotography and cannot be used visually. The focal plane is at the front of the optical system so it is not possible to use an eyepiece. It is recommended to only use narrowband filters that are optimized for fast systems such as the Antlia ALP-T FAST or Baader Highspeed CMOS filters. Specifications Optical design Rowe-Ackermann Schmidt Astrograph Aperture 279 mm (11") Focal length 620 mm Focal ratio f/2.2 Resolving power 0.41 arc seconds Image circle 43.3 mm, 4.0° Usable field 52 mm, 4.8° with only minimal performance loss at edge of FOV Light gathering power 1588 times the human eye Central obstruction diameter 114 mm (41% of aperture diameter) Wavelength range 400 - 700 nm Spot size < 4.4μm RMS across image circle Optical coatings StarBright XLT Off-axis illumination 83% at 21 mm off-axis Optical window diameter 68 mm Backfocus with included camera adapter 55 mm Backfocus from top of threaded collar 72.8 mm Mount attachment CGE dovetail plate on top and bottom of tube Focuser Ultra-Stable Focusing System Included connection adapters M48 x 0.75, M42 x 0.75 Tube length 838.2 mm Tube weight 19.5 kg Tube diameter 330.2 mm SKU CE-91076 Items included RASA 11" 2 x CGE dovetail Dew cap M42 camera adapter M48 camera adapter Fan battery pack Filter solutions The RASA 11" has a much greater backfocus than the smaller 8" version, so it is possible to use standard filter drawers and DSLRs. We recommend the Baader UFC filter drawer system for most applications. Usage with Baader UFC In order to connect DSLR cameras with Baader T-Rings, you will need the following pieces: UFC Base Chamber S70 - BA2459110 UFC S52 dovetail adapter - BA2459119 UFC RASA 11" adapter - BA2459126 UFC filter slider - BA2459112 In order to connect common CMOS cameras with 17.5mm of backfocus, you will need the following pieces: UFC Base Chamber S70 - BA2459110 UFC M42, M48 or M54 camera adapter - BA2459115, BA2459116 or BA2459117 UFC RASA 11" adapter - BA2459126 UFC 15 - 20mm variable extension - BA2459145 UFC 15mm extension - BA2459142 UFC 5mm extension - BA2459141 UFC filter slider - BA2459112 Downloads Celestron RASA 11" manual
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