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Askar 1x Field Flattener for 140APO

Askar 1x Field Flattener for 140APO

by Askar
SKU ASK-ASKAR140FL
CA$461.00 - CA$461.00
CA$461.00
CA$461.00 - CA$461.00
CA$461.00
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  • Engineered for the Askar 140APO Triplet Refractor
  • 1x Flattener Preserves Native f/7 Focal Ratio
  • Corrects a 44mm Full-Frame Image Circle
  • Standard 55mm Back Focus Requirement
  • Triplet Optical Design for Sharp, Coma-Free Stars
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Askar 1x Field Flattener for 140APO

    The Askar 1x Field Flattener is engineered specifically for the Askar 140APO refractor, maintaining the native 980mm focal length and f/7 focal ratio of the telescope. Its triplet optical design corrects for field curvature across a 44mm full-frame image circle and establishes a standard 55mm back focus for seamless integration with your existing imaging train.

    Triplet Optics for a 44mm Corrected Image Circle

    Refractor optics naturally produce a curved focal plane, resulting in elongated stars at the corners of an image. This 1x flattener uses a three-element, air-spaced triplet lens system to counteract this effect, ensuring pinpoint stars across the entire field of a full-frame sensor. By supporting a 44mm image circle, you can leverage large-format CMOS and CCD cameras without significant vignetting or distortion at the edges.

    55mm Back Focus and Flexible Camera Connections

    Designed for straightforward integration, this flattener requires a standard 55mm back focus from the base of its M48 male thread. This spacing is compatible with most ZWO, QHY, and other dedicated astronomy cameras when used with their stock adapters, as well as with standard DSLR/mirrorless T-rings. The 0.79kg unit provides multiple camera-side connections, including M68×1, M54×0.75, and M48×0.75 threads, and features internal M48 threads for mounting 2-inch filters within the optical path.

  • What is the purpose of the Askar 1x Field Flattener for the 140APO?

    Its primary purpose is to correct the natural field curvature of the Askar 140APO refractor. This correction ensures that stars are sharp and round not just in the center of your image, but all the way to the corners, which is essential for astrophotography with modern large-format sensors.

    Does this Askar flattener change the focal length of my 140APO?

    No. This is a 1x flattener, meaning it does not reduce or extend the focal length. When attached to the Askar 140APO, the telescope's focal length remains 980mm and the focal ratio stays at f/7.

    How does the Askar 1x flattener improve images of the Andromeda Galaxy (M31) with the 140APO?

    A large target like the Andromeda Galaxy (M31) will fill the frame of a full-frame sensor on the 140APO. Without the flattener, stars in the outer arms and surrounding the galaxy would appear stretched. With the flattener's 44mm corrected circle, the entire galaxy and its surrounding starfield will be rendered with sharp, pinpoint stars from edge to edge.

    How do I achieve the correct 55mm back focus with the Askar 1x Flattener?

    The 55mm distance is measured from the base of the flattener's M48 male thread to your camera's sensor. Most dedicated astronomy cameras and DSLR/mirrorless cameras with a T-ring are designed to meet this 55mm standard using a combination of included extension rings. You must ensure your total imaging train (off-axis guider, filter wheel, etc.) adds up to exactly 55mm for optimal performance.

    Can I use 2" filters with the Askar 140APO flattener?

    Yes. The flattener has a built-in M48×0.75 filter thread on the telescope side of the camera adapters. This allows you to directly screw in any standard 2-inch astronomy filter for light pollution reduction or narrowband imaging.

    Will the Askar 1x flattener work on telescopes other than the 140APO?

    No, this flattener is optically matched specifically for the Askar 140APO triplet refractor. Using it with other telescopes will likely result in poor field correction and degraded image quality. For other telescopes, you should use the flattener designed for that specific optical system.

  • Optical Design 3-Element Triplet
    Magnification 1x
    Compatible Telescope Askar 140APO
    Focal Length (with 140APO) 980mm
    Focal Ratio (with 140APO) f/7
    Corrected Image Circle 44mm
    Back Focus 55mm (from base of M48 male thread)
    Camera Connections M68×1, M54×0.75, M48×0.75
    Filter Thread Internal M48×0.75 (for 2" filters)
    Weight 0.79kg
  • Askar 1-Year Warranty