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Dall Kirkham telescope is one of the Cassegrain optical systems, with a concave elliptical mirror for the primary and with a convex spherical mirror for the secondary. The Mewlon is a new concept telescope that is made in mass production by virtue of Takahashi's high polishing technology in having made a great number of various non-spherical reflecting optical systems.


* Designing concept

The Mewlon-210 is designed mainly based on the visual performance that is the basic function of an astronomical telescope. Therefore, this optical system can be used better for visual observations than for taking deep-sky astrophotograph which requires sharp images over the wide photo field. In the view field, this optical system can produce so good images as a Newtonian can do. Therefore, this can be said to be an ideal telescope to do the planetary observations as well as to the lunar observation. Thus, the Mewlon-210 has been developed as a very compact and highly easy-to-use telescope by simplifying the aim of the use.


* Performance

The Dall Kirkham telescope is a well known and excellent optical system from the old times. However, it has been hardly produced as a commercial telescope because of difficulty of making its primary mirror of a concave elliptical surface. The image focused in the center is a very sharp without any aberration like as in a Newtonian telescope. The images toward the edge are generally fine within the view field, although it is sometimes said that some amount of coma aberration is visible.

In the astrophotography, especially in highly magnified lunar and planetary photography, you can expect a good result with your Mewlon-210. When it is compared with a traditional Cassegrain telescope, the Dall Kirkham telescope can be easily assembled and aligned in the process of production. This optical system as a highly precision telescope can maintain stable performance. As mentioned before, it is so suitable especially for lunar and planetary observations because its long focal length by a spherical convex secondary mirror (a parabolic convex mirror in a Cassegrain) can easily produce high magnification.


* Operation

The handling of your Mewlon is so simple. At first, set the devo-tail plate under the main tube into the devo-tail adapter attached on the equatorial mount. The finder is so firmly attached on the tube that you can hold the tube by the finder when you set the tube into de devo-tail adapter.

Your Mewlon-210 is a Cassegrain type so that the length of the tube is far shorter than that of a Newtonian telescope with the same aperture and the same focal length. Moreover, it is a very compact and light-weighted, which permits you to use a relatively smaller equatorial mount. Because of this, the whole system becomes totally compact and easy-to-use.

The optical axis alignment can be made with the three screws provided in the secondary mirror section. Once aligned, the optical axis will become hardly out of order except when a great shock is given to the telescope.

Focusing is made by the mirror shifting method, turning the focusing knob clockwise or counter-clockwise. This system will permit you to focus smoothly with your fingers when a camera is attached on the visual back, without giving an extra load of a camera as in the rack and pinion focusing system.

From Takahashi Seisakusho Ltd. product manual (1993)







7th in being manufactured










Focal Length



mm (%)



diameter (mm)

f Ratio Lt Grasp Resolution





Tube OD





length mm






Image  Circle



180 2160 / 1763 59 (33%) 54 12 / 9.8 621 0.64 13.0 210 640 6.3 16 / 36


210 2415 / 1961 70 (33%) 65 11.5 / 9.3 900 0.55 13.4 244 700 8.1 18 / 39


250 3000 / 2307 75 (30%) 70 12 / 9.2 1276 0.46 13.8 280 895 12.5 21 / 42


250 2500 / 1825 / 3780 75 (30%) 70 10 / 7.3 / 15.1 1276 0.46 13.8 280 945 12 40 / 35 /44


300 3572 / 2739 100 (33%) 95 11.9 / 9.1 1837 0.39 14.2 324 1094 23.3 25 / 42


300 2960 / 2160 / 4475 100 (33%) 95 9.9 / 7.2 / 14.9 1837 0.39 14.2 324 1045 27 40 / 35 / 44


System charts





1990/3: New product Mewlon-180 Dall Kirkham announcement (180-2160).

1991/11: New product Mewlon-250 Dall Kirkham announcement (250-3000).

1992/7/18-19: Mewlon-300T at JTB show'92 exhibition.

1986/9/16-22: Mewlon-300/EM-2000 at Photokina/Cologne exhibition.

1993/7/18-19: Mewlon-210 at JTB show'93 exhibition.

1993/11: New product Mewlon-210 Dall Kirkham announcement (210-2415).

1994/5: New product Mewlon-300 Dall Kirkham announcement (300-3572).

1994/7: Mewlon-300 at JTB show'94 exhibition.

2009/12/10: New product Mewlon CR corrector, CR0.73X reducer and CR1.5X extender units for Mewlon-250 / Mewlon-300.

2010/12/4: New product Mewlon-250CRS corrected Dall Kirkham announcement (250-2500).

2011/6/1: New product Mewlon-300CRS corrected Dall Kirkham announcement (300-2960).

2016/9/9: New product Mewlon-180C announcement (180-2160).









Mewlon-180 System Chart
Mewlon-180 50.8 System Chart
Mewlon-180 R&P System Chart
Mewlon-180C System Chart
Mewlon-180C R&P System Chart
Mewlon-210 System Chart
Mewlon-210 R&P System Chart
Mewlon-250 System Chart
CR instruction manual for Mewlon-250
Mewlon-250CR System Chart
Mewlon-250CR EXT-1.5X System Chart
Mewlon-250CRS System Chart
Mewlon-250CRS EXT-1.5X System Chart
Mewlon-300 System Chart
CR instruction manual for Mewlon-300
Mewlon-300CR System Chart
Mewlon-300CR EXT-1.5X System Chart
Mewlon-300CRS System Chart
Mewlon-300CRS EXT-1.5X System Chart




Takahashi Seisakusho Ltd






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