iOptron Photron 250mm f/8 Ritchey-Chretien Catadioptric Telescope (OTA Only)

Utilizing the same hyperbolic primary and secondary mirror design used in the Hubble Space Telescope, the Keck telescopes, and the ESO Very Large Telescope, the iOptron Photron 250mm f/8 Ritchey-Chretien Catadioptric Telescope represents the medium-aperture in the series and is ideally suited for both star-gazing and astrophotography. Despite its larger mirror and long focal length, it delivers views that are free from off-axis comas, or spherical and chromatic aberrations, yet maintains a highly-portable form factor. The low thermal-expansion quartz primary and secondary mirrors are treated with highly-reflective dielectric coatings that, when combined with internal knife-edge baffles, limit distortion as the mirrors heat while limiting stray internal light and maximizing light transmission. All this translates to bright and sharp high-contrast images with accurate color fidelity across the entire distortion-free field of view.

Unlike other catadioptric designs, this RCT has a fixed primary mirror to eliminate the image-shift that is common with conventional configurations that move the mirror forward and back to focus the image. With the primary mirror fixed in-place, iOptron installed a precise two-speed Crayford-style focuser with a 10:1 reducer that allows for fast coarse and precise fine focusing without the backlash that occurs in the more common rack-and-pinion design � essential for astrophotography or splitting objects that are close together, like binary stars. To ensure complete coverage of today's imaging sensors, the focuser has a 2" drawtube and comes with three extension rings to help users achieve the proper back-focus distance. The larger drawtube also allows the use of large eyepieces which generally have longer eye reliefs to make visual observations much more comfortable; and comes with a 1.25" reducer to enable the smaller and more common-sized eyepieces and accessories to be easily used.

Intended for those who have a reliable support system, iOptron offers the RCT here as an OTA-only option. A long Losmandy-style dovetail plate is factory-installed to make it compatible with a wide variety of heavier-duty alt-azimuth, equatorial, and GoTo mounts that can carry a minimum payload of at least 35 pounds. To make adding accessories, such as a smaller guide scope, or to piggy-back imaging or DSLR cameras for wide-field photography, a smaller Vixen-style dovetail plate is also pre-installed on the top of the OTA.