This kit consists of a high performance flattener lens, a high performance focal reducer and a connecing tube ring. It improves image quality of photography by achieving a flat focal plane and reduces the focal length of the FL55SS by 0.79 times. The flattener lens corrects aberration on the periphery of a photographic field of view and it keeps images of stars sharp throughout the photographic field. The focal reducer achieves faster photographic speed of F4.3 by reducing the scope's focal length.
The flattener HD lens improves off-axis image quality greatly with a minimum change of the focal length. The focal reducer HD5.5 reduces the focal ratio of the FL55SS scope from F5.5 to F4.3 (by 0.79 times) while keeping a 44mm image circle that covers imaging sensors of full frame DSLR cameras.
Generally astrophotographers are annoyed with the drop-off of light toward the edge of illuminated field of view when taking faint deep-sky objects with a telephoto lense or dedicated astrophoto instrument. Although this may be corrected by complicated image processing on a PC, it all depends on the image quality of an original photograph. The focal reducer HD5.5 works to keep a large 86% illuminated field of view even at the very edge of a 44mm image circle in combined with the flattener HD lens. Astrophotography of nebulae and star clusters are fun with the focal reducer HD Kit.
86% with use of DSLR cameras with the full frame size of imaging sensors. 97% with use of DSLR cameras with the APS-C size of imaging sensors.
FL55SS with the flattener HD lens plus focal reducer HD5.5
Standard telephoto lens or astrograph
The same anti-reflection AS coatings that are used for our high-end VSD100F3.8 renowned for extremely high light transmission (99.9% per surface) are provided on each of the lens surfaces of the flattener HD lens and focal reducer HD5.5. Besides, elaborate matte-finishes are given to eliminate internal reflections and loss of light completely.
Flattener HD for FL55SS
Flattener HD for FL55SS plus focal reducer HD5.5
Focal reducer HD5.5