Astro-Tech 0.8x reducer/field flattener for f/6 refractors Old Style with 42mm Adapter only.

While this Astro-Tech #ATR8 0.8X reducer/field flattener is designed for prime focus astrophotography with quality f/6 focal ratio apo refractors such as the Astro-Tech AT72EDII and AT130EDT, it will also work well with Astro-Tech and other brand refractors in the f/5.5 to f/7 range that use a 2" focuser.

For example, the fully-multicoated Astro-Tech ATR8 converts the 430mm focal length f/6 Astro-Tech AT72ED refractor into a 344mm f/4.8 lens for faster and wider field astronomical and terrestrial photography, while the 777mm f/7 Astro-Tech AT111EDT converts into a 622mm f/5.6.

In addition to reducing the focal length of the telescope and thereby increasing the photographic speed, the ATR8 flattens the normal field curvature inherent in all refractors to provide images that are sharply focused out to the very corners of a large format DSLR chip. Stars look sharp and point-like all the way across the field in your images. You don't have to worry about photos that are sharp in the center and blurry at the edges.

The Astro-Tech ATR8 reducer/flattener fits 2" focusers. The 2" telescope-side barrel is threaded for standard 2" filters and has a beveled safety groove. The camera side of the reducer has a 42mm T-threads  to connect to a T-ring and camera body. A thread-on metal cover protects the T-threads when the reducer is not in use, while a slip-on dust cover is provided for the 2" scope-side barrel. Back focus is 55mm from the shoulder of the reducer to the image plane, the standard spacing for 35mm and DSLR camera bodies. The image circle at the focal plane is 42mm in diameter.