Our photo-visual apochromatic Barlow element is made with real ED glass and offers the correction of the off-axis coma in Newtonian telescopes. This Barlow enables the observation of planets and deep sky objects at the edge of the 1¼" eyepiece field with a quality similar to axis quality. Dobson owners in particular will appreciate this.

The photographically coma-corrected field is designed for the APS-C format (100% illumination at 105mm focus distance). Due to its unique quality, this APO Barlow lens also is usable on telescope systems such as refractors, SC’s and others. An image quality that hardly any other Barlow lens on the market can match, no matter how expensive it is.

The optics, calculated by Gerd Düring from Germany, have been optimized to an aperture ratio of f/4 for systems with a parabolic mirror. This Barlow uses the ED glass FK61 (comparable to Ohara FPL51) as an ED element, it is cemented and equipped with a broadband multicoating on both sides, the transmission is better than 99% in the spectrum from 400nm to 700nm.

The optimal back focus is 105mm from the middle of the last lens. The focal length is - 62.9mm, the free aperture is 22mm.

This coma-correcting Barlow works with a focus distance of 105mm 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 common with Newton / Dobsonian telescopes.

Characteristics:

• Modern optic calculation
• FK61 ED glass
• Visually and photographically usable
• High-quality MC coatings
• Excellent image quality
• Thread 28,4mm for filters 1¼"
• focus shift outwards 60.65 mm
  

Delivery:

• APM coma-correcting barlow element 1¼" 2.7x
• 1.25" Body  with thread 28,4mm
• Packaging