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APM Comacorrecting 1 1/4" ED Barlow 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 coma-correcting 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 coma-correcting 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.

This coma-correcting Barlow works with a focus distance of 105 as a perfect optical glass path corrector with integrated coma correction and thus allows the use of normal binocular approaches on telescopes with a short back focus, as is usual with Newton / Dobsonian telescopes.

The 2-part adapter is photo-visual optimized, visual with the optimal backfocus of 105 mm with the new APM-Deluxe Centering Brass-Clamp. This top Deluxe adapter has a length of 55 mm and can be unscrewed, than you get a photographic T2 thread (M42 x 0.75 mm) for use with DSLR with T2 adapter ring.

First results with the ED-Barlow has been amazing!

Delivery contains:
  • 1 1/4" ED-Barlow Element
  • 2-part Adapter


Connection to camera:
T2 thread
Connection to eyepiece:
1 1/4"
Connection to telescope:
1 1/4" and 2"
Brass Clamp
mechanical path:
ca. 120 mm
Broadband Multicoating
Housing material:
Unobstructed diameter:
22 mm
2.7 x
2 Lenses
Optical design:
Cemented Doublet
Made for:
Newtonian Telescopes (optimized for f/4)
Fully illuminated field:
minimum 30 mm
Resulting focal length:
- 62.9 mm
ca. 7 oz