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ZWO FF70-APO 70mm Quadruplet Refractor F/7.0
ZWO FF70-APO 70mm Quadruplet Refractor F/7.0
ZWO FF70-APO 70mm Quadruplet Refractor F/7.0
ZWO FF70-APO 70mm Quadruplet Refractor F/7.0
ZWO FF70-APO 70mm Quadruplet Refractor F/7.0

ZWO FF70-APO 70mm Quadruplet Refractor F/7.0

by ZWO
SKU ZWO-FF70-APO
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$599.00 USD
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$599.00 USD
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  • 70mm Aperture
  • 490mm Focal Length (f/7)
  • 4-Element Quadruplet Apochromatic Optics
  • 44mm Full-Frame Image Circle
  • Native Flat-Field Design
  • 2.4" Dual-Speed 1:10 Rack & Pinion Focuser
  • 5.51 lbs. OTA Weight
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  • Description
  • FAQ
  • Specifications
  • In the Box
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  • ZWO FF70-APO 70mm Quadruplet Refractor F/7.0

    The ZWO FF70-APO 70mm Quadruplet Refractor combines a 490mm focal length (f/7) with a four-element optical design to deliver a flat field across a 44mm image circle. This apochromatic refractor weighs only 5.51 lbs for the optical tube assembly and has a retracted length of just 372.5mm, making it well suited to lightweight, portable mounts. The rigid 2.4" dual-speed rack and pinion focuser offers 1:10 fine focusing, and it delivers sharp star fields with edge-to-edge performance across the frame.

    ZWO FF70-APO: A 70mm Quadruplet for Portable Wide-Field Imaging

    The FF70-APO is engineered as a complete imaging solution for astrophotographers who prioritize portability without sacrificing optical quality. Its 70mm aperture and 490mm focal length provide a wide field of view for large nebulae, entire constellations, and expansive star fields. The integrated design means you spend less time on setup and more time imaging.

    This refractor is designed for both the traveling imager and the backyard astronomer seeking a lightweight, high-quality instrument. Its low weight suits portable equatorial mounts, including harmonic drive mounts. ZWO designed it for both visual observation and astrophotography.

    A 4-Element, Air-Spaced APO Design with ED Glass

    At the core of the FF70-APO is a four-element air-spaced apochromatic optical train. This quadruplet design incorporates one element of Extra-Low Dispersion (ED) glass, which significantly reduces chromatic aberration, the false color fringing that can appear around bright stars. The result is improved color correction and image clarity.

    Rather than relying on a separate field flattener, the FF70-APO uses all four elements together to deliver a flat imaging field. With this self-flattened design there is no back focus to calculate: once the imaging accessories are attached and the telescope is in focus, you can start imaging.

    70mm Aperture and 490mm Focal Length at f/7

    The combination of a 70mm aperture and a 490mm focal length strikes a balance between light-gathering capability and a wide field of view. The f/7 focal ratio works with a wide range of cameras, and this configuration is well suited to large celestial targets.

    With a 490mm focal length, you can frame enormous objects like the Andromeda Galaxy (M31), the North American Nebula (NGC 7000) in a single shot using a full-frame sensor. The FF70-APO also suits mosaics of the Milky Way or capturing the full extent of faint, sprawling hydrogen clouds.

    A Native Flat Field with a 44mm Full-Frame Image Circle

    The FF70-APO is designed to fully illuminate a 44mm image circle, making it compatible with full-frame (36x24mm) DSLR, mirrorless, and dedicated astronomy cameras. It delivers sharp star fields with excellent edge-to-edge performance across the frame.

    The native flat-field design is a significant advantage. There is no need to purchase an external flattener or worry about achieving a precise spacing. Focus can be achieved within a back focus range of 32.5 to 82.5 mm, measured from the M54-M48 interface shoulder. This simplifies your imaging train.

    The 2.4-inch Rack & Pinion Focuser with 1:10 Fine Adjustment

    To support modern imaging payloads, the FF70-APO is equipped with a rigid 2.4" rack and pinion focuser. The dual-speed 1:10 fine adjustment knob allows precise focus control, which is critical for achieving the sharpest possible stars.

    The rear of the focuser includes a 360° rotator, for precise camera angle adjustment when framing a target. This is essential for composing your shot or for creating multi-panel mosaics. The focuser has screw positions for an EAF bracket, so a ZWO EAF (Electronic Automatic Focuser, sold separately) can be fitted for motorized focusing.

    Flexible 32.5mm-82.5mm Back Focus and Extension Tube

    While the FF70-APO does not require a fixed back focus distance for optical correction, it provides a generous focus range to accommodate a wide variety of accessories. The system is designed to achieve focus with cameras and accessories placed within a range of 32.5mm to 82.5mm from the M48x0.75 thread shoulder.

    The included photographic extension tube provides the necessary connections for most cameras and filter wheels. It features standard M48x0.75 and M54x0.75 male threads for direct attachment. A built-in 2" filter thread on the M48 adapter allows you to easily install a light pollution or narrowband filter directly into your imaging train.

    Natively Flat Design: No External Flattener Required

    One of the most significant features of the ZWO FF70-APO is its integrated quadruplet design that produces a flat field natively. This eliminates one of the most common challenges in astrophotography: purchasing, installing, and correctly spacing a separate field flattener or reducer/flattener.

    This design simplifies the entire imaging process. You can connect your camera directly (or with standard extensions) to the rear M48 or M54 threads and focus. No additional optical corrector is needed, which saves time and keeps the imaging train simple.

    Imaging and Visual Use with Full-Frame Cameras or Eyepieces

    ZWO designed the FF70-APO for astrophotography with sensors up to full-frame size and for visual observation. Its apochromatic optics with one ED element reduce chromatic aberration for clear, high-contrast views. The wide field of view makes it an excellent rich-field telescope for sweeping through the Milky Way or observing large open star clusters like the Pleiades (M45).

    To use the FF70-APO visually, you will need to add a 1.25" or 2" star diagonal and an eyepiece. The maximum visual path length is 117 mm from the 1.25" eyepiece holder and 127 mm from the 2" eyepiece holder. The light weight also makes it a practical "grab-and-go" visual scope.

    CNC-Machined Tube with a 93.2mm Retractable Dew Shield

    The entire optical tube of the FF70-APO is crafted using precision CNC machining, and finished with high-quality paint. Inside, the dew shield is covered with matting paint to reduce stray light reflections and improve contrast.

    The retractable dew shield, with an outer diameter of 93.2mm, serves two purposes: it blocks stray light from entering the objective and helps prevent dew from forming on the lens during long nights. When retracted, it reduces the telescope's overall length, making it even more compact for storage and transport. The handle has a finder base slot and two more finder bases sit on either side of the focuser, so a finder scope can be moved without disassembly and other accessories can be mounted.

    A Portable 5.51 lb. OTA Measuring Just 372.5mm

    Weighing only 5.51 lbs for the optical tube alone, and 6.61 lbs with the included handle, tube rings, and 230mm Vixen-style dovetail, the FF70-APO is lightweight. Its retracted length of just 372.5mm makes it easy to pack and transport to dark sky sites. This portability is a key advantage for imagers who travel or those who want a simple, quick setup.

    This low weight suits portable equatorial mounts, including harmonic drive mounts. Add the weight of your camera and accessories and compare the total with your mount's rated payload.

    First Night Out: Getting Started with the FF70-APO

    Setting up the FF70-APO for its first imaging session is straightforward. Start by attaching the included tube rings and the 230mm Vixen dovetail plate. Mount the telescope onto your equatorial mount and balance it in both axes. Attach your camera to the rear M48 or M54 thread, using the photographic extension tube if needed.

    Next, mount your guide scope or finder scope to one of the two findershoe bases. After connecting all your cables, perform your mount's polar alignment routine. Point the telescope to a bright star and use a Bahtinov mask to achieve critical focus with the 1:10 fine-focus knob. Once focused, you can slew to your target, use the 360° rotator to frame it, and begin your imaging sequence.

    ZWO FF70-APO vs. FF90-APO: Portability and Aperture

    Choosing between ZWO's flat-field refractors involves a direct trade-off between light-gathering power and weight. The FF90-APO offers a larger 90mm aperture, which provides greater resolving power for finer details and collects more light for imaging fainter objects. However, this comes at the cost of increased size and weight.

    The FF70-APO's primary advantage is its portability. At a fully equipped weight of 6.61 lbs, it is lighter than its larger sibling and suits more compact mounts. Its wider field of view is also better suited for capturing very large celestial structures. If your priority is a lightweight, grab-and-go rig for wide-field imaging, the FF70-APO is the better fit.

  • Do I need a field flattener for the ZWO FF70-APO?

    No. The ZWO FF70-APO has a 4-element quadruplet optical design with a native flat-field design. You do not need a separate flattener or a back focus calculation: once the imaging accessories are attached and the telescope is in focus, you can start imaging across the 44mm image circle.

    What is the image circle of the ZWO FF70-APO and what cameras does it support?

    The FF70-APO has a 44mm image circle, which supports full-frame sensors (36x24mm) as well as smaller APS-C and Micro Four Thirds sensors. Astronomy cameras connect to the M48x0.75 or M54x0.75 threads, and DSLR or mirrorless cameras connect through a camera adapter (not included).

    How does the ZWO FF70-APO's 490mm focal length frame the Andromeda Galaxy (M31)?

    The 490mm focal length suits framing the Andromeda Galaxy (M31). When paired with a full-frame camera, you can comfortably capture the galaxy's entire bright core and its sprawling spiral arms in a single frame, along with its satellite galaxies M32 and M110. This makes it an excellent choice for capturing one of the sky's largest and most impressive deep-sky objects.

    Is the 6.61 lb. weight of the ZWO FF70-APO suitable for a portable harmonic mount?

    Yes. At 6.61 lbs (3.0 kg) with handle, rings and dovetail, the FF70-APO is light enough for portable mounts, including harmonic drive mounts. Add the weight of your camera and accessories and compare the total with your mount's rated payload.

    What is the purpose of the included photography extension tube with the FF70-APO?

    The photography extension tube serves as an adapter to connect various cameras and accessories. It provides the standard M48x0.75 and M54x0.75 male threads needed for most astronomy cameras and T-rings. It also contains a built-in 2-inch (M48) filter thread, allowing you to place a filter in the optical path easily.

    Can I use 2-inch filters with the ZWO FF70-APO?

    Yes. The included photographic extension tube has a built-in M48x0.75 filter thread, the thread used by 2-inch mounted filters. You can thread a filter directly into the adapter before attaching your camera.

    How do I attach a guide scope to the ZWO FF70-APO?

    The handle has a finder base slot, and there are two finder bases on either side of the focuser. You can mount a finder or guide scope in any of these positions and move it without disassembling anything.

    Can the ZWO FF70-APO be used for visual astronomy?

    Yes. ZWO designed the FF70-APO for both visual observation and astrophotography. Its apochromatic optics reduce chromatic aberration for high-contrast views of stars, planets and deep-sky objects. You will need to supply your own 1.25" or 2" diagonal and eyepieces to use it visually.

    How does the 2.4-inch focuser on the FF70-APO handle heavy imaging trains?

    ZWO fits a rigid 2.4" dual-speed rack and pinion focuser with 1:10 fine adjustment and a 360° rotator. ZWO does not publish a load rating for the focuser.

    Is a focal reducer available for the ZWO FF70-APO?

    No dedicated reducer is named for the FF70-APO. The telescope is designed for use at its native 490mm focal length and f/7 with no extra flattener; the extension tube's M64-to-M54 section carries a built-in reducer attachment thread.

  • SKU ZWO-FF70-APO
    Optical Design Apochromatic Refractor
    Number of Elements 4 (Quadruplet)
    Aperture 70mm (2.8")
    Focal Length 490 mm
    Focal Ratio f/7
    Focuser 2.4" Rack & Pinion
    Focuser Speed Dual Speed 1:10
    OTA Weight 5.51 lbs. (6.61 lbs. with handle, rings and dovetail)
    Telescope Series ZWO Refractors
    Mount Type No Mount - OTA Only
    Electronics OTA Only - No Electronics
    Image circle / fully illuminated field 44 mm (full frame)
    Required back focus (native, with built-in corrector) No fixed requirement; focus range 32.5-82.5 mm from the M48x0.75 thread
    Rear / camera-side connection M48x0.75 male and M54x0.75 male (2" filter thread built in)
    Tube length (retracted) 372.5 mm
    Tube outer diameter 78 mm (dew shield 93.2 mm)

    • ZWO 70 mm APO Refractor OTA

      × 1

    • Mounting Rings

      × 2

    • 230 mm Vixen Dovetail Plate

      × 1

    • Findershoes

      × 2

    • Photography Extension Tube

      × 1

    • Warranty Card

      × 1

    • Inspection Card

      × 1

    • User Manual

      × 1

  • ZWO Warranty