Lunar souther region by Dominique Dierick
Dall-Kirkham Mewlon series reflectors are long focal length telescopes with high F/D focal ratio. The primary mirror is ellipsoidal while the secondary mirror is spherical. The surface accuracy of the optics is at least λ/20.
The CRS models incorporate a field corrector with ED glass lenses that provides a F/10 focal ratio but above all a higher corrected field than on conventional Mewlon telescope. The motorized focusing, ASCOM compatible, is done by translating the secondary mirror. The fans responsible for heating the primary mirror are managed by 3 temperature sensors located inside and outside the tube.
The Mewlon-250CRS is perfectly suited for planetary observation and imaging, due to its long focal length. It is also ideal for deep sky applications; equipped with the F/7.3 reducer it will allow the imaging of compact objects such as planetary nebulae or galaxies. The integrated 7x50 finder scope is adjustable and serves as a handle for transport.
The optical tube assembly is delivered with a pair of rings connected by a massive plate located under the tube.
| Characteristic | Takahashi Mewlon-250CRS reflector |
| Optical design | Modified Dall-Kirkham |
| Combination | Concave elliptical primary mirror + convex spherical secondary mirror + field corrector |
| Diameter | 250 mm |
| At prime focus | |
| Focal length | 2500 mm |
| Focal ratio | F/10 |
| Image circle diameter | 40 mm |
| Metal Back Distance | 147.9 mm |
| With RD CR0.73X focal reducer | |
| Focal length | 1825 mm |
| Focal ratio | F/7.3 |
| Image circle diameter | 35 mm |
| Metal Back Distance | 72.2 mm |
| With EX CR1.5X focal extender | |
| Focal length | 3780 mm |
| Focal ratio | F/15.1 |
| Image circle diameter | 44 mm |
| Metal Back Distance | 117.5 mm |
| Characteristic | Takahashi Mewlon-250CRS reflector |
| Length of the optical tube assembly | 945 mm |
| Diameter of the optical tube assembly | 280 mm |
| Weight | 12 kg |
Spot-diagram of Takahashi Mewlon-250CRS reflector at prime focus
Spot-diagram of Takahashi Mewlon-250CRS reflector with RD CR0.73X focal reducer
| System-chart of Takahashi Mewlon-250CRS reflector | Download |
| System-chart of Takahashi Mewlon-250CRS reflector with EX CR1.5X | Download |
| ASCOM ActiveFocuser Driver | Download |
| INDI ActiveFocuser Driver | Download |
| Instruction manual of Takahashi Mewlon-250CRS reflector | Dowload |
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Lunar souther region by Dominique Dierick
NGC 4565 by Dominique Dierick
Saturn by Jean-Luc Dauvergne