William RedCat 91WIFD - 91 mm f/4.9 Flatfield Refractor for Astrophotography

William Optics REDCAT 91 mm f/4.9 WIFD Travel Apochromat and Astrograph

The William RecdCat 51 is a successful model and has found its following. It was supplemented by the more powerful sister models RedCat 61 and RedCat 71. William Optics now also offers all these telescopes with a - rack and pinion-based - internal focusing system; they are designed for mobile astrophotography and are supported by smaller mounts, in some cases even by stable star trackers.

The logical extension of these models is the RedCat 91 WIFD, which combines internal focusing with a particularly large aperture. Due to 6.3 kg weight, however, the mount should be somewhat more stable.

This apochromatic refractor is aimed at all astrophotographers and nature photographers who are looking for a portable and tack-sharp telephoto lens. Due to the 5-element Petzval design, a fully corrected image field of 50 mm diameter without chromatic aberration is achieved. This means that even full-frame cameras can be used. In fact, the correction is very good even over a 55 mm diameter field, so the telescope can also be used for medium format astro cameras. Focusing works internally, as with many telephoto lenses, but via knobs with an additional fine focus knob (dual speed), as with telescopes.

The application areas of the RedCat 91 apo:

Astrophotography: With 448 mm focal length and fast f/4.9, short exposure times are possible. The working distance of 55 mm allows using all popular astro cameras. mirrorless system cameras and DSLR/SLR cameras. The fine focusing allows a precise focus, the rotation the selection of the suitable image section. The supplied Bahtinov mask helps with focusing and is integrated in the objective cap.

Countryside photography and animal photography: The RedCat 91 is also perfect for, for example photographing animals. Internal focusing allows you to focus without shifting the weight, and therefore also without changing the position. The image field is thus not altered. The image quality will impress you. A photo tripod is necessary for use.

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