APM Coma correcting 1 1/4" ED Barlow Element 2.7 x
Designed by Gerd Düring / Germany
Due to Forum discussions, Gerd Düring in Germany designed this new, improved coma correcting ED Barlow lens, optimized for parabolic mirrors with f-ratio f/4.
Our totally new photo-visual apochromatic Barlow with real ED glass, calculated for the correction of Off-Axis Coma in Newtonian telescopes. This Barlow allows you to observe planets and deep sky objects at the edge of the field of view with the same quality as on axis. Dobsonian users will benefit greatly as many times the objects are not exactly centered on axis.
The photographic coma corrected field is perfect for APS-C. Because of its unique qualities, this barlow can also be used with refractors, SCT etc. with an image quality no other Barlow of equal price can reach.
This Barlow uses as the ED element the Chinese ED glass FK61 (similar to Ohara FPL51) The lenses are soft cemented and applied with a broadband multicoating on both sides with over 99 % transmission of wavelengths 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.
- 1 1/4" ED-Barlow Element with 28.4 mm Filter thread