The Mewlon 250CRS currently has an extensive lead time. Prices and specifications may vary. Contact us for more information.
The Takahashi Mewlon 250CRS is a Dall-Kirkham reflector designed for planetary imaging and observation. The optical design combines an ellipsoidal primary mirror and spherical secondary mirror, with the surface quality of the optics being extremely accurate at λ/20.
The Mewlon CRS models have an integrated field corrector with ED glass lenses which provide a much higher corrected field than the smaller Mewlon models. This makes the 250CRS suitable for imaging of deep sky objects such as planetary nebulae and galaxies with an image circle of 40mm at prime focus.
The Mewlon 250CRS has a native focal length of 2500mm and a focal ratio of f/10, making it the ideal instrument for planetary use. The motorized secondary mirror allows precise focusing with either the included hand controller or over ASCOM. Additionally, the tube features three cooling fans for the primary mirror with temperature sensors both inside and outside the tube.
A 0.73x focal reducer is available (sold separately), reducing the focal length to 1825mm and focal ratio to f/7.3 for wider views and faster exposure times. A 1.5x focal extender is also available.
Spot diagram of Takahashi Mewlon 250CRS at prime focus.
Spot diagram of Takahashi Mewlon 250CRS with RD CR 0.73x focal reducer.
|Optical design||Modified Dall-Kirkham reflector
||Concave elliptical primary + convex spherical secondary + field corrector
||Motorized secondary mirror focuser|
|Primary mirror diameter
|Focal length at prime focus
|Focal ratio at prime focus
|Backfocus distance at prime focus
|Tube diameter||280 mm|
|Tube length||945 mm|
|Tube weight||12 kg|
|Prime focus focal length||2500 mm
|Prime focus focal ratio
|Prime focus backfocus distance
|Prime focus image circle||40 mm|
|RD CR 0.8x reducer focal length
RD CR 0.8x reducer focal ratio
RD CR 0.8x reducer backfocus distance
RD CR 0.8x reducer image circle
|EX CR 1.5x extender focal length||3780 mm|
|EX CR 1.5x extender focal ratio||F/15.1|
|EX CR 1.5x extender backfocus distance||117.5 mm|
|EX CR 1.5x extender image circle||44 mm|