Skip to content
Price match 30-day returns* Talk to an astronomer before you buy
QHYCCD QHYOAG-L Pro Off-Axis Guider

QHYCCD QHYOAG-L Pro Off-Axis Guider

by QHYCCD
SKU QHY-110171
$280.00 USD - $280.00 USD
$280.00 USD
$280.00 USD - $280.00 USD
$280.00 USD
Price Match Policy!
  • Large 14 x 10mm Prism
  • Only 12mm of Back Focus Used
  • For Full Frame & Medium Format Sensors
  • M62 and M54 Telescope Interfaces
  • 1.25-inch Helical Focuser with Lock
Backordered
Request Stock Alert
Availability Info
Worldwide Shipping
Guiding Calculator

Will it guide your telescope?

Check the scale ratio, PHD2 binning and guide star odds for the QHYCCD QHYOAG-L Pro Off-Axis Guider with your telescope.

Check my guiding setup
  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • QHYCCD QHYOAG-L Pro Off-Axis Guider

    The QHYCCD QHYOAG-L Pro solves the challenge of finding guide stars in long-focal-length systems by using an oversized 14 x 10mm prism to fully illuminate large-format guide sensors. Occupying just 12mm of back focus, it is built for imagers using full frame and medium format CMOS sensors. The OAG-L Pro offers M62/0.75 or M54/0.75 telescope interfaces (with the included spacers) and a precise 1.25-inch helical focuser, creating a solid connection between your telescope, filter wheel, and camera.

    The 14 x 10mm Prism: Illuminating Large Guide Sensors

    At long focal lengths, the field of view shrinks, making guide stars scarce. The solution is a guide camera with a larger sensor, but standard off-axis guiders with small prisms can cause severe vignetting, losing the advantage. The QHYOAG-L Pro incorporates a large 14 x 10mm prism, significantly bigger than typical 8x8mm prisms, to direct ample light to guide cameras with large sensors like the QHY5III174M.

    This ensures you can leverage the full field of your guide sensor to find a suitable star, even in sparse star fields. While a small amount of darkening may occur at the very edges, it does not impact guiding performance.

    Rigid, 12mm Profile for QHY Filter Wheel Integration

    Differential flexure between the guide scope and main telescope is a primary source of guiding errors. An OAG avoids it by using the same light path for both imaging and guiding. The QHYOAG-L Pro achieves this in a slim profile that uses only 12mm of precious back focus.

    • Solid Connection: The body features six 3mm through-holes designed for a direct, bolted connection to QHY filter wheels, giving a solid, parallel and reliable connection.
    • Broad Compatibility: It connects directly to the QHYCFW3XL filter wheel. An included adapter also provides solid connections for the QHYCFW3L and QHYCFW3M.
    • Flexible Interfaces: The included 5mm M62 spacer and 5mm M62-to-M54 spacer let you finish the telescope side in M62 or M54 threads.

    1.25" Helical Focusing and Prism Positioning

    Achieving perfect focus with your guide camera is critical for tight, round stars. The QHYOAG-L Pro is equipped with a 1.25-inch helical focuser that allows for fine, precise adjustments to match the guide camera's focus to your main imaging camera. A lock knob secures the focuser once set, preventing any drift during an imaging session.

    The prism itself is also adjustable. A side-mounted locking knob allows you to slide the prism stalk in or out of the main light path. If the prism shows in your main camera's image, move it further away from the sensor until it no longer obstructs it.

    QHYOAG-L Pro vs. OAG-M Pro: Choosing for Your Sensor Size

    QHY offers two "Pro" models to match different imaging setups. Both share the same 14 x 10mm prism and 12mm thickness; their interfaces differ.

    • QHYOAG-L Pro (This Model): Designed for larger setups. It is the ideal choice for full frame and medium format sensors like the QHY600 or QHY461, pairing perfectly with the large-format QHYCFW3XL filter wheel.
    • QHYOAG-M Pro: M54 telescope side, made for full frame and APS-C cameras with the QHYCFW3L or QHYCFW3M filter wheels.

  • What is the main advantage of the QHYOAG-L Pro's large 14 x 10mm prism?

    The large 14 x 10mm prism prevents vignetting on guide cameras with large sensors (like the QHY5III174M). This allows you to take full advantage of the guide camera's wide field of view to find a suitable guide star, which is especially critical when imaging at long focal lengths where stars are more sparse.

    I'm using a long focal length SCT with a full-frame QHY600 camera. Is the QHYOAG-L Pro the right choice?

    Yes, absolutely. The QHYOAG-L Pro is designed specifically for this type of setup. Its large prism ensures your guide camera is well-illuminated despite the narrow field of view of the SCT, and its six-screw mounting gives a solid connection to the filter wheel and camera.

    How do I focus the guide camera with the QHYOAG-L Pro?

    The QHYOAG-L Pro features a 1.25-inch helical focuser. First, achieve focus with your main imaging camera. Then, loosen the lock knob on the OAG's focuser and rotate the focusing ring until the stars in your guide camera are sharp. Once focused, tighten the lock knob to secure the position for the rest of your imaging session.

    How do I position the prism to avoid shadowing my medium format sensor?

    Loosen the prism position locking knob on the side of the OAG body. While viewing a test image from your main camera, carefully slide the prism stalk outwards, away from the center of the light path, just until its shadow disappears from the corner of your frame. Then, re-tighten the knob. This maximizes the light reaching the guide camera without interfering with your primary image.

    Will the QHYOAG-L Pro connect to my QHYCFW3L filter wheel?

    Yes. While the QHYOAG-L Pro connects directly to the larger QHYCFW3XL, it comes with a dedicated adapter for the QHYCFW3L and QHYCFW3M filter wheels included in the box.

    How much back focus does the QHYOAG-L Pro use?

    The main body of the QHYOAG-L Pro consumes only 12mm of back focus. This does not include the thickness of any adapters used on the telescope side, which must be accounted for separately in your calculations.

  • Prism Size 14 x 10mm
    Back Focus Used 12mm (excluding adapter)
    Suitable Sensor Size Full frame and medium format CMOS
    Telescope Interface M62/0.75 or M54/0.75 (with the matching adapters)
    Guide Camera Interface 1.25 inch, helical focuser with focus lock
    Mounting Six 3mm through holes for QHYCFW3 filter wheels and adapter rings
    Compatible Filter Wheels QHYCFW3XL directly; QHYCFW3L and QHYCFW3M with the included adapter
    Recommended Guide Camera Large-sensor guide cameras such as the QHY5III174M; smaller cameras also compatible
    Weight About 165g

    • QHYOAG-L Pro

      × 1

    • 5mm M62 to M54 (female) spacer

      × 1

    • 5mm M62 (female) spacer

      × 1

    • Adapter for QHYCFW3L and QHYCFW3M

      × 1

    • M3x6mm screws

      × 5

    • M3x18mm screws

      × 8

    • M3x20mm screws

      × 5

    • M3x10mm thumb screws

      × 3

    • 1mm hex key

      × 1

  • QHYCCD 2-Year Warranty