| This fully-multicoated visual/photographic focal reducer for the Takahashi Mewlon Dall-Kirkham reflectors shortens each telescope’s focal length and effective focal ratio by a factor of 0.8x.
With the reducer in place, the 8.3" Mewlon 210 changes from a 2415mm focal length f/11.5 system to a 1961mm focal length f/9.3. This increases the image circle from 18mm at the focal plane at f/11.5 to 39mm at f/9.3 with the reducer in place. The field of view is 1.2° using the reducer.
By the same token, the 9.8" Mewlon 250 changes from a 3000mm focal length f/12 to a 2307mm f/9.2 system. This increases the image circle from 21mm at the focal plane at f/12 to 42mm at f/9.2, with a 1° field of view.
The 11.8" Mewlon 300 changes from a 3572mm focal length f/11.9 to a 2739mm f/9.1 system, with the image circle increasing from 25mm to 42mm. With the reducer, the field of view is 45 arc minutes in diameter.
In addition to reducing the Mewlon focal length and focal ratio, this reducer also acts as a field flattener and corrector to reduce the coma inherent in the Dall-Kirkham design as well as the curvature of field that put stars at the edge of the field subtly out of focus. Coma is reduced and stars remain focused to the edges of the field with the reducer in use, allowing large photographic blowups that stay sharp all across the print.
The reducer has a 2" barrel that slips into the Mewlon focuser. A safety groove machined into the barrel helps keep the reducer and attached camera from falling should the focuser thumbscrew accidentally loosen during use. The camera side of the reducer has standard 42mm photographic T-threads for connection to your camera.
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