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

Designed by Gerd Düring / Germany

Our totally new photo-visual apochromatic Barlow with real ED glass, calculated for the correction of Off-Axis Coma at 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. Especially Dobsonian user will profit because most time 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, no other Barlow will reach, equal of its price.

Due Forum discussions pushed, Gerd Düring in Germany designed this new, improved coma correcting ED Barlowlens, optimized for parabolic mirrors with f-ratio f/4.

This Barlow uses as ED-element the Chinese ED glas FK61 (similar to Ohara FPL51), the lenses are soft cemented and applied on both sides with a broadband multicoating with over 99 % transmission for wavelength from 400 nm to 700 nm.

The optimal backfocus is 105 mm from center of the last lens. The focal length of the barlow is - 62.9 mm, the clear aperture 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 backfocus.

First results with the ED-Barlow have been amazing!

Delivery contains:
  • 1 1/4" ED-Barlow Element with 28.4 mm Fiterthread


mechanical path:
18.5 mm
Broadband Multicoating
Housing material:
Unobstructed diameter:
22 mm
2.7 x
2 Lenses
Optical design:
Cemented Doublet
M 28.4 mm Filterthread both sides
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
ca. 2 oz.