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APM 1.25 Inch Coma Corrector ED 6.25x Double Barlow Lens

|, APM, Telescope Accessories, Barlow Lenses, Coma Correctors, and Focal Extenders|APM 1.25 Inch Coma Corrector ED 6.25x Double Barlow Lens

APM 1.25 Inch Coma Corrector ED 6.25x Double Barlow Lens

$276.00

Out of stock

APM 1.25 Inch Coma Corrector ED 6.25x Double Barlow Lens is a unique photo-visual apochromatic 2.7x Barlow with real ED glass that be combined with a second APM 2.7x Barlow to increase the magnification factor to 6.25x.

Out of stock

Description

APM 1.25 Inch Coma Corrector ED 6.25x Double Barlow Lens

APM 1.25 Inch Coma Corrector ED 6.25x Double Barlow Lens is a unique photo-visual apochromatic 2.7x Barlow with real ED glass, designed by Gerd Düring in Germany.  This lens is calculated for the coma correction in Newtonian telescopes and can now be combined with a second APM 2.7x Barlow (sold separately) at a specific distance to increase the magnification factor to 6.25x. Coma correction is retained, as is the corrected flat field.

On its own, this single barlow lens cell has a magnification factor of 2.7x and will provide a fully illuminated imaging field of 26mm at a back focus of 104.1mm (measured from the shoulder of the lens cell). It is optimized for F/4 Newtonian type telescopes and when used with such also offers coma correction. This is particularly useful for manual Alt-Az Dobsonian users who can enjoy a coma free view of objects as they drift across the field of view.

To use the Barlow in a 6.25x configuration, simply add a second 2.7x lens cell to the other end of the extension so there is a lens at each end. This configuration yields a corrected field of 14mm at a distance of 83.1mm from the shoulder of the lens cell (84mm from the center of the last element).

The double Barlow permits very high magnification with Newtonian telescopes for planetary imaging while still retaining a respectably low F ratio needed for high frame rates. Simply set your camera sensor back 83.1mm from the shoulder of the last lens cell to have the correct back focus for imaging.

Features a double lens group using Chinese ED glass FK61 (similar to Ohara FPL51). The lenses are soft cemented and applied on both sides with a broadband multi-coating with over 99% transmission for wavelength from 400 nm to 700 nm.

The design of each single Barlow element follows APM’s principles of outstanding optical quality.

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Package Includes:

  • Two 1.25″ ED Barlow Elements
  • One 1.25″ Extension Tube

Product Specifications:

Coating: Broadband Multi-coating
Material: Aluminium
Magnification: 6.25x
Lenses: 2 x 2 Lenses
Optical design: Cemented Doublet
Connecting thread: M 28.4 mm Filter thread both sides
Back focus: 84 mm (from the center of the last element)
Made for: Newtonian telescopes (optimized for f/4)
Fully corrected field: 14mm
Fully illuminated field: 14mm

APM Double Barlow

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