APM 1 1/4″ Coma Correcting ED 2.7x Barlow Element




Delivery contains:

  • 1 1/4″ ED-Barlow Element with 28.4 mm Fiter thread



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APM Comacorrecting 1 1/4″ ED Barlow Element 2.7 x

Designed by Gerd Düring / Germany

APM’s new photo-visual apochromatic Barlow is made with real ED glass, and is calculated for the correction of Off-Axis Coma with Newtonian telescopes. This Barlow allows you to observe planets and deep sky objects at the edge from the 1.25″ field of view with the same quality as on axis.  Dobsonian users especially will find this advantageous as during most views the objects are not exactly centered on axis.

The photographic coma corrected field is perfect for APS-C. Because of its unique quality this barlow can also be used with refractors, SC etc. with a image quality that no other Barlow’s in the same price range will achieve.

Gerd Düring in Germany designed this new, improved coma correcting ED Barlow lens, which is optimized for parabolic mirrors with an f-ratio  off/4.

This Barlow uses as ED-element 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 optimal back focus is 105 mm from center of the last lens. The focal length of the barlow is – 62.9 mm, with the clear aperture at 22 mm.

This barlow offers with its 22 mm aperture in secondary focus a 100 % illuminated  photo-visual field for APS-C when used with 105 mm back focus.

First results with the ED-Barlow have been amazing!



mechanical path: 18.5 mm
Coating: Broadband Multi-coating
Housing material: Aluminium
Unobstructed diameter: 22 mm
Magnification: 2.7 x
Lenses: 2 Lenses
Optical design: Cemented Doublet
Connecting thread: M 28.4 mm Filter thread both sides
Backfocus: 105 mm from Center last Lens
Made for: Newtonian Telescopes (optimized for f/4)
Fully illuminated field: minimum 30 mm
Resulting focal length: – 62.9 mm
Weight: ca. 2 oz.


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