iOptron Photron 250mm f/8 Ritchey-Chrétien Catadioptric GoTo EQ Telescope

iOptron Photron 250mm f/8 Ritchey-Chrétien Catadioptric GoTo EQ Telescope

iOptron Photron 250mm f/8 Ritchey-Chrétien Catadioptric GoTo EQ Telescope

B&H # IOP250RCT MFR # 12250
Special Order
Expected availability: 2-4 weeks

Product Highlights

  • 250mm Ritchey-Chrétien Catadioptric OTA
  • 2000mm Focal Length, f/8 Focal Ratio
  • Precise 10:1 Dual-Speed Crayford Focuser
  • CEM60 Motorized EQ GoTo Mount
  • 358,000+ Object Computer Controller
  • Multiple Alignment Assistance Options
  • 3-Speed Zero-Backlash Electronic Focuser
  • 1.25" Eyepiece and Dielectric Diagonal
  • 8x50 Finderscope with Bracket
  • Portable, Sturdy Tri-Pier Support System
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Options: CEM60 GoTo EQ Mount, Tri-Pier

CEM25P GoTo EQ Mount, 2" Tripod

Not available with current selections

CEM60 GoTo EQ Mount, Tri-Pier OTA Only

Special Order

iEQ45 Pro GoTo EQ Mount, 2" Tripod

Not available with current selections

Aperture: 250mm (10"), f/8

150mm (6"), f/9

Not available with current selections

200mm (8"), f/8

Not available with current selections

250mm (10"), f/8
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iOptron Photron overview

  • 1Description

Combining a precision large-aperture optic with a full-featured GoTo mount and exceptionally sturdy support system, plus a suite of useful accessories, the iOptron Photron 250mm f/8 Ritchey-Chrétien Catadioptric GoTo EQ Telescope (RCT) is a complete system ideally suited to detailed visual observation or all types of astrophotography. Mounting the superior optics of the RCT on a fully motorized equatorial mount allows users to accurately track objects for long periods of time without the field rotation that happens when using alt-azimuth mounts. Without the field rotation, long exposure times of several minutes can be used without star streaking or blurring. Added to the optical tube assembly and the mount is the highly portable and incredibly stable tri-pier hybrid support system. iOptron also includes a precision electronic focuser, an eyepiece and diagonal, a finderscope and bracket, and an additional counterweight to properly balance the entire optical system.

  • Photron 250mm f/8 Ritchey-Chrétien 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-Chrÿtien Catadioptric Telescope (RCT) represents the medium-aperture class in the series and is ideally suited for both stargazing and astrophotography. Despite its larger mirror and long focal length, it delivers views that are free from off-axis comas and 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 optical tube assembly (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 piggyback imaging or DSLR cameras for wide-field photography, a smaller Vixen-style dovetail plate is also pre-installed on the top of the OT

    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 and 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
    • 10 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 reduce acclimation time and help 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
    • Optical tube assembly onlymount 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 piggybacking 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
  • CEM60 Center-Balanced Equatorial Mount

    The CEM60 Center-Balanced Equatorial Mount from iOptron features an innovative weight distribution design coupled with precise extended tracking capabilities to create a mount ideally suited for astrophotography or long-term observation. Its center-balanced design puts the optical tube assembly (OTA) weight directly over the mount's center of gravity, which gives it better stability and a greater payload capacity over other EQ mounts. Additionally, the counterbalance shaft length is adjustable to keep it from interfering with whatever pier or tripod is being used.

    The drive has a peak-to-peak error of ±5 arcsecond, but the Go2Nova hand controller is equipped with periodic error correction (PEC) capabilities that allow you to train out the errors. This precision error correction allows for long-exposure astrophotography or other layering techniques that require shorter exposures with filter or other accessory changes. In addition to astroimaging, the extended tracking accuracy makes long-term observation of specific objects or areas of interest easier.

    For setup and alignment, the CEM60 comes with the AccuAligning Illuminated Polar Scope. The mount is designed so that the declination shaft doesn't block the AccuAligning scope, which makes it accessible at all times for checking or correcting the polar alignment. A built-in 32-channel GPS receiver sends information such as location and local time to the Go2Nova controller for faster and easier setup.

    Included with the mount is the Go2Nova 8407+ controller. This handheld computer guider has a database of over 349,000 objects and is flash updatable from the iOptron website with firmware updates that increase its accuracy and add celestial objects. The database includes the planets, galaxies, star clusters, quasars, and nebulae, as well as seven astronomical catalogs including Messier and NGC IC. It also has stars, comets, asteroids, and constellations and can store up to 60 user-defined objects to easily find and go to favorite objects. The mount has nine slew speeds up to 3.75°/second and can be manually controlled for quick observations.

    A hard carrying case with die-cut custom-fit foam comes with the mount and is designed to hold and protect it during transport or storage.

    • Motorized and computer-guided equatorial mount with 60 lb payload capacity
    • Innovative design puts the payload weight on the mount's center of gravity for greater stability and better counter-balancing
    • Non-contact magnetically loaded gear meshing system
    • Precise azimuth adjustment dials
    • 8" Losmandy/Vixen dual saddle accepts any compatible OTA up to 60 lb
    • AccuAligning polar scope with dark-field illumination for polar alignment
    • Declination shaft doesn't obstruct alignment scope for faster and easier polar alignment
    • Gear switches on both right ascension (RA) and declination (dec) axes for fast movement
    • Built-in 32-channel GPS receiver communicates information to the Go2Nova controller
    Motors and Gears
    • Precision stepper motors with 0.06 arcsecond accuracy for precise GoTo capability and accurate tracking
    • 146mm, 288-tooth aluminum RA and dec worm wheels
    • Screw/worm-type latitude adjuster for precision adjustments
    • Vise-type latitude bearing locks system for solid positioning
    • Permanent Periodic Error Correction (PPEC) removes inaccuracies inherent in gears and allows for more accurate tracking, especially for long-exposure astrophotography
    • Peak-to-peak periodic error of ±5 arcsec
    • Nine slew speeds: 1x, 2x, 8x, 16x, 64x, 128x, 256x, 512x, Max (3.75°/sec)
    • Slew speed and direction controlled via Go2Nova controller
    • 110-240 VAC power adapter included
    Instrument Panel and Input Panel
    Instrument Panel:
    • Two 12 VDC power outlets for powering the CCD camera or electric focuser
    • Four USB 2.0 ports with Type A connector for connecting to accessories
    • 6P6C port that can be used to bridge the guiding port or accessories with a 6P6C/6P4C plug
    • The USB hub is non-powered and will draw power from a source, such as a computer USB port
    • The ports on the instrument panel are connected to the input panel located next to the polar scope
    Input Panel:
    • One 12 VDC power input, 5 A max
    • One USB 2.0 port with Type B connector
    • One 6P6C port


    Counterweight and Shaft
    • Adjustable counterweight shaft reduces or eliminates interference with tripod or other equipment
    • 1.1x17.7" (28x450mm) stainless steel counterweight shaft
    • Included 21 lb (9.5kg) counterweight
    Go2Nova 8407+ Hand Controller
    • 358,000-object database
    • User-friendly menu-driven interface
    • 9-speed slew control with quiet mode
    • Database includes stars, constellations, and seven complete astronomical catalogs including Messier and NCG IC
    • Up to 60 user-defined objects to easily find your favorites
    • Enter specific RA and dec coordinates of objects for immediate GoTo
    • 8-line, 21-character/line, red-light backlit LCD screen
    • One-star, multi-star, polar and SolarSys alignments
    • Periodic Error Correction (PEC) function reduces or eliminates RA tracking errors for long-exposure astrophotography
    • Programmable anti-backlash adjustment for smoother tracking
    • Updatable firmware through built-in serial port
    • Computer control with planetarium software
    • Integrated ST-4 autoguiding port
    • Built-in heater for larger operating temperature range
  • Tri-Pier for GoTo Mounts (White/Black)

    iOptron combined the strength and stability of a pier, with the portability and leveling flexibility of a tripod to produce their Tri-Pier; offered here with white legs and a black center column. Designed to provide a rock-solid platform for their GoTo mounts, the pier and leg tops are made of lightweight and durable aluminum, with stainless steel leg extensions. Its feet have built-in vibration-suspension pads for increased stability and visual clarity. It has a payload capacity of 220 pounds to handle even the largest OTAs and accessories, with an adjustable height from 31.5 to 42.5" and an uneven ground range of 3.35" (8.5cm). It folds up into a relatively compact 26 x 12.8" package, and the legs store inside the pier.

    • CEM60/CEM60EC, iEQ45/iEQ45 Pro, iEQ30/iEQ30 Pro, MiniTower/MiniTower II/MiniTower Pro mounts
  • Electric eFocuser for Photron Ritchey-Chrétien Telescopes

    Eliminate vibrations and achieve finer and more precise focusing on your 6, 8, or 10" Photron Ritchey-Chrétien telescope with iOptron's Electric eFocuser. Once installed on the OTA, the unit plugs into the auxiliary port on compatible mounts for power, and allows it to be controlled using the Go2Nova computer hand controller running the current firmware version. A precise stepper motor with a synchronous drive belt delivers three speeds — low, medium, high — without vibration or noise. While the eFocuser is primarily designed for the iOptron Photron Ritchey-Chrétien series telescopes, it will also fit other RC scopes such as GSO, OPT's TPO, Astronomics' Astro-Tech, and Orion; it may work with other RC scopes that use the similar dual-speed focuser.

    Using an electric focuser eliminates the need to touch knobs which cause vibration and allows a level of precision that hand-focusing is usually unable to achieve. The eFocuser also locks the position when the control button is released to eliminate backlash — a valuable function for astrophotography or when trying to resolve dim or close objects like binary stars or cluster

    Compatible Mounts
    • CEM25/CEM25P/CEM25EC
    • CEM60/CEM60EC
    • iEQ30 Pro
    • iEQ45 Pro
    • May work with other OTAs that use a similar dual-speed focuser
    • May require update to the most current hand controller firmware
    UPC: 813578010711
  • 52° 25mm Plossl Eyepiece (1.25")

    The iOptron 52° 25mm Plossl Eyepiece is designed for comfortable near and deep-space astronomical observation. The relatively long focal length will produce a moderate magnification on most OTAs, making it a versatile addition to any astronomer's kit.

    It is engineered with anti-reflective fully multi-coated optical surfaces to ensure bright and clear high-contrast images with true color transmission across the entire 52° field of view. With a 1.25" diameter barrel, it will fit the most common size drawtubes, visual backs, and accessories. The housing has a textured collar for safe handling in the cold, and a fold-down eyecup makes this eyepiece comfortable when viewing for extended periods with or without eyewear.

    UPC: 813578010698
  • 90° Dielectric Star Diagonal (1.25")

    Use the iOptron 90° Dielectric Star Diagonal to place your head in a comfortable viewing position when your refractor or catadioptric optical tube assembly (OTA) is aimed at or near the zenith. Built with a dielectric hard-coated BK-7 glass mirror, the diagonal transmits more than 99% of the incoming light to ensure clear and bright high-contrast images while maintaining maximum resolution.

    Designed to be lightweight and durable, the diagonal features an aluminum housing with a black anodized finish. The 1.25" barrel and eyepiece holder makes it compatible with the most popular size focusers, drawtubes, and accessories; and the brass compression ring in the eyepiece holder ensures your eyepieces won't get marked or marred when locked into place. An internal integrated safety stop in the eyepiece holder protects the mirror and ensures a long life.

    UPC: 813578010674
  • 8x50mm Finderscope with Bracket (Red)

    The iOptron 8x50mm Finderscope is an ideal finder for deep-sky observers who need additional magnification and aperture to be able to detect smaller and dimmer objects outside our solar system like binary stars, nebulae, or galaxies. It comes with its own bracket that is outfitted with a dovetail mount for compatibility with a wide array of finder saddles, and three thumbscrews that enable precise alignment with the OTA.

    UPC: 813578010667
  • 11 lb Counterweight for iEQ45/CEM60 EQ Mounts

    iOptron's 11 lb Counterweight is designed to provide additional counterbalance for the iEQ45/Pro and CEM60/EC mounts, or any other mount with a counterweight shaft outside diameter of less than 1.11" and the carrying capacity to handle it. The weight uses a brass compression to provide a more secure locking method through distributed surface contact to ensure it won't slip or shift on the counterweight shaft, unlike a traditional single-point-of-contact locking screw and a pin.

In the Box
Bundle Items
  • Battery Holder
  • 2" Extension Ring
  • 2 x 1" Extension Rings
  • Limited 1-Year Warranty
  • AccuAligning Polar Scope
  • Go2Nova 8407 Hand Controller
  • 21 lb (9.5 kg) Counterweight
  • Stainless Steel Counterweight Shaft
  • Power Adapter
  • Hard Aluminum Carrying Case
  • Limited 2-Year Warranty
  • Limited 2-Year Warranty
  • Pulley
  • Control Cable
  • Synchronous Belt
  • Limited 1-Year Warranty
  • 2 x End Caps
  • Limited 1-Year Warranty
  • Limited 1-Year Warranty
  • Mounting Bracket
  • Limited 1-Year Warranty
  • Locking Screw
  • Limited 1-Year Warranty
Table of Contents
  • 1Description
  • Photron 250mm f/8 Ritchey-Chrétien Catadioptric Telescope (OTA Only)
    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
  • CEM60 Center-Balanced Equatorial Mount
    Mount Type Equatorial
    Load Capacity 60 lb (27.2 kg), excluding counterweight
    Mount 8" Losmandy/Vixen dual saddle
    Motor Precision stepper motor
    0.06 arcsec accuracy
    Right Ascension Worm Wheel 146mm, 288 tooth aluminum
    Declination Worm Wheel 146mm, 288 tooth aluminum
    GPS Internal 32-channel GPS receiver
    GoTo Capability Go2Nova 8407+ hand controller
    Altitude / Latitude Adjustment Altitude: ±8°
    Latitude: 0 to 70°
    Polar Axis Scope AccuAligning dark field illuminated
    Includes Tripod/Pier No
    Power Source 12 VDC, 2 A
    100 to 240 VAC, adapter included
    Consumption: 0.6 A (when tracking), 1.1 A (in GoTo mode)
    Operational Temperature -4 to 113°F (-20 to 45°C)
    Mount Size Base: 5.9" (15 cm)
    Weight 27 lb (12.3 kg)
    Packaging Info
    Box Dimensions (LxWxH) 25.2 x 18.0 x 9.5"
  • Tri-Pier for GoTo Mounts (White/Black)
    Payload Capacity 220 lb / 100 kg
    Maximum Leg Spread 48.8" / 124.0 cm
    Dimensions Pier diameter: 5.7" / 14.5 cm
    Adjustable height: 31.5 - 42.5" / 80.0 - 108.0 cm
    Fully folded: 12.8 x 26.0" / 32.5 x 66.0 cm
    Weight 25.8 lb / 11.7 kg
    Packaging Info
    Box Dimensions (LxWxH) 29.3 x 13.8 x 13.3"
  • Electric eFocuser for Photron Ritchey-Chrétien Telescopes
    Motor Stepper with synchronous belt
    Power Via mount
    Dimensions 3.2 x 2.2 x 2.1" / 8.2 x 5.6 x 5.4 cm
    Weight 19.2 oz / 544.3 g
    Packaging Info
    Box Dimensions (LxWxH) 4.0 x 4.0 x 4.0"
  • 52° 25mm Plossl Eyepiece (1.25")
    Focal Length 25mm
    Barrel Diameter 1.25"
    Eye Relief Not specified by manufacturer
    Apparent Field of View 52°
    Dimensions Not specified by manufacturer
    Weight Not specified by manufacturer
  • 11 lb Counterweight for iEQ45/CEM60 EQ Mounts
    Dimensions Height: 1.5" / 3.8 cm
    Diameter: 5.8" / 14.8 cm
    Counterweight shaft hole: 1.1" / 2.9 cm
    Weight 11.0 lb / 5.0 kg
    Packaging Info
    Box Dimensions (LxWxH) 10.0 x 9.6 x 4.5"

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