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IOptron Photron 250mm F/8 Ritchey-Chretien Catadioptric Telescope (OTA Only)(Ioptron Photron 250mm F 8 Ritchey Chretien Catadioptric Telescope Ota Only)

IOptron Photron 250mm F/8 Ritchey-Chretien Catadioptric Telescope (OTA Only)(Ioptron Photron 250mm F 8 Ritchey Chretien Catadioptric Telescope Ota Only)

Original price was: $333.00.Current price is: $97.99.

SKU: DGFUB 62414422032 Categories: Optics, Optics & Surveillance Tags: IOptron 6113, New-arrivals, Optics, Telescopes

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Description
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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.

Optical Tube Assembly

Large 250mm (9.8″) clear aperture provides performance while keeping the OTA portable; 110mm secondary mirror
Long 2000mm focal length provides a high magnification potential and moderate focal ratio for astrophotography
Moderate f/8 focal ratio allows for shorter exposure times for imaging than slower OTAs
Ritchey-Chrétien catadioptric design delivers views free from off-axis comas, or spherical and chromatic aberrations
Low thermal-expansion quartz primary and secondary mirrors limit distortion as the mirrors heat
Highly reflective dielectric mirror coatings transmit more than 99% of incoming light to ensure bright and clear images
Ten internal knife-edge baffles diminish stray light, improving contrast for visual and imaging applications
Fixed-position primary mirror eliminates image-shift common in other catadioptric designs
Three integrated primary mirror cooling fans reduces acclimation time and helps to eliminate distortion due to mirror heating; runs on eight user-supplied AA batteries
Resolution: 0.46 arcsec
10:1 dual-speed linear-bearing Crayford focuser allows for fast coarse and precise fine focus without backlash for tack-sharp focusing; with tension-adjustment knob and drawtube lock-knob
Oversized 3.3″ drawtube ensures complete coverage of imaging sensors to eliminate or limit vignetting; and terminates in a 2″ eyepiece holder that allows the use of larger eyepieces to make viewing easier and more comfortable; with etched scale in inches and millimeters for precise repeatability
Factory-installed mounting plate for user-supplied finder

Mounting

Optical tube assembly only – mount and tripod required for proper use
Long Losmandy-style dovetail plate is compatible with many alt-az, equatorial, and GoTo mounts
Weight: 35 pounds
Secondary upper Vixen-style dovetail plate enables easy mounting of smaller guide-scopes or to piggy-back imaging or DSLR cameras for wide-field astrophotography

Included Accessories

Reducer Adapter:

2″-to-1.25″ reducer allows the use of the smaller, more common-sized accessories and eyepieces in the larger focuser drawtube

Extension Rings:

Three focuser rings allow for increased back-focus distance to ensure the focal plane properly lands on imaging sensors or specialized visual equipment
Rings can be used one at a time, or stacked as needed
Simple screw-together design requires no tools or permanent modification
Includes two (2) 1″ tubes and one (1) 2″ tube

UPC: 813578010629

250mm Ritchey-Chretien Catadioptric OTA
2000mm Focal Length, f/8 Focal Ratio
Low Thermal-Expansion Quartz Mirrors
Dielectric Mirror Coatings
Ten Internal Knife-Edge Baffles
10:1 Dual-Speed Crayford Focuser
Primary Mirror Cooling Fan System
Three Back-Focus Extension Rings
Losmandy-Style Dovetail Mounting Plate
OTA Only – Mount and Tripod Required

In the Box

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

Battery Holder
2″ Extension Ring
2 x 1″ Extension Rings
Limited 1-Year Warranty

Optical Design	Ritchey-Chretien catadioptric
Aperture	250mm
Focal Length	2000mm
Focal Ratio	f/8
Eyepiece Barrel Diameter	2″ 1.25″ with included reducer
Diagonal	None
Finderscope	None
Tripod	None
Mount Type	Losmandy-style dovetail plate
Power Source	8 x AA batteries for cooling fans
Optical Tube Length	28.4″ / 72.1 cm
Weight	35.0 lb / 15.9 kg

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