This unusual lens from ASA (Astro Systeme Austria) makes rich-field telescopes even richer, whilst correcting aberrations. Thus, a wide field telescope is able to grab even more ‘space’ in a single frame. With a reduction ratio of between .75 to .73, the examples quoted are that an f/4.7 becomes f/3.4 and an f/4 is corrected to f/2.9. By interposition of this lens, owners of an already abbreviated f/3 can expect an f/2.2 as a result. As imagers will already know, these reductions mean wider real fields and shorter exposures (or deeper shots with the same exposure).
Allowing comfortable chip coverage of cameras employing Kodak’s 8300 sensors, it can be persuaded to flood almost all of the APS-C (except for the corners). The device fits a two-inch focuser, offering a rear T-thread fitting.
Price: £739
For more information, contact Modern Astronomy www.modernastronomy.com
