Starizona Apex ED 0.65x Reducer / Flattener

Article number: ApexED-XX
Availability: More on the Way to us
Delivery time: Special Order

With the Apex ED reducer, an f/5.5 apo refractor becomes an incredibly fast f/3.6 astrograph. A slower f/9 telescope like an RC becomes a speedy f/5.9 system. The reduction factor provides a 1.5x wider field of view and shortens exposure times by a factor of 2.4x!

The Apex ED reducer features extra-low disperion glass to eliminate chromatic aberration and to provide sharp star images over a 30mm image circle, capable of working with most popular CCD, CMOS and DSLR cameras up to APS-C format.

The Apex ED reducer fits into a standard 2" focuser. It has M42 T-threads on the camera side, and it can accept a standard 2" (M48) filter on the telescope side for easy use of light-pollution or other filters. On Meade ACF telescopes, the Apex can be attached using a 2" visual back.

For select refractors, we make optional threaded adapters to allow direct threaded attachment of the Apex reducer, eliminating the possibility of tilt introduced by the standard focuser clamp ring.

"L" and "S" Versions

To optimize the Apex ED for the best possible performance, there are two versions of the lens. The "L" version is designed for telescopes with focal lengths 500mm and longer. This includes most larger (100mm+) refractors and all RC and ACF telescopes. The "S" version is for telescopes with focal lengths from 300-500mm, including most 60-80mm apo refractors.


The nominal backfocus distance from the Apex ED reducer's T-threads to the image sensor depends slightly on the focal length of the telescope. It is at least 55mm in all configurations. The table below shows the optimum backfocus for various focal lengths. Please contact us for help in choosing the right adapters or spacers necessary for your setup.

Apex Backfocus Chart



  • Reduction Factor: 0.65x
  • Image Circle: 30mm
  • Backfocus: 55-62mm (depending on telescope focal length)
  • Optical Design: 5 elements with ED glass, fully multi-coated
  • Barrel Diameter: 2"
  • Camera Thread: M42 (T-thread)
  • Filter Thread: M48 (2" filter)
  • Overall Length (Apex ED L): 2.97"
  • Weight (Apex ED L): 0.7 lbs
  • Overall Length (Apex ED S): 3.26";
  • Weight (Apex ED S): 0.72 lbs
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