Takahashi - Mewlon 300 Dall-Kirkham Telescope

Takahashi - Mewlon 300 Dall-Kirkham OTA

• The Mewlon combines refractor-like performance in a larger folded optic reflector design.


• The 300 optical tube assembly has 11.8" of aperture and a focal ratio of 11.9.


• Comes with Fraulhaber German electric focus motor for secondary (no image shift!)


• OTA includes 11X70 finder, double finder bracket and tube weight.


• Photo shows optional mount and pier not included.

The Mewlon Series of Dall-Kirkham Telescopes by Takahashi© combines refractor-like performance in a larger folded optic reflector design.

The optional NJP mount provides a stable, accurate platform for the M-300. The integral polar alignment telescope and R.A. axis level make accurate polar alignment to within 2 arc minutes of the celestial pole quick and easy. The reticle is designed to be used in either Hemisphere until the year 2030. No other manufacturer uses such a highly accurate polar telescope.

The Mewlon series of Dall-Kirkham Cassegrain telescopes from Takahashi offer the experienced observer a level of performance and portability not found in other Cassegrain telescopes mass produced for amateurs. Classical Cassegrain telescopes offer excellent performance but they are extremely expensive to produce at large apertures. By concentrating on the Dall-Kirkham Cassegrains, the Mewlon offers a professional level of performance within reach of most amateurs.

The Mewlons use an ellipsoidal figure on the primary mirror and a spherical figure on the secondary. By focusing on very tight tolerances for these surfaces, Takahashi is able to deliver a compact telescope with reasonable aperture and high resolution. Where fast F/ratios are not required, the F/12 Mewlons provide excellent contrast by utilizing a smaller secondary mirror than comparable Cassegrain designs. Secondary obstruction as a percentage of diameter is 29-31% on the Mewlons. Classical Cassegrain telescopes usually have secondary obstruction of 32% or greater. Commercial Schmidt-Cassegrains have secondary obstructions of approximately 38% for F/10 systems. Ritchey-Chretien Cassegrains have even more secondary obstruction making them less suitable for visual, high contrast applications.

Takahashi uses extensive knife-edge baffling to minimize stray reflections as well as a specially designed tube that also acts as a light baffle. The result is an instrument that rivals an excellent long-focus Newtonian or refractor for contrast and sharpness. Some opticians have criticized the Dall-Kirkham design as having unacceptable coma. With most eyepieces (including Panoptics & Naglers) the coma is negligible and well outside the field of view. Stars are much smaller and sharper than in commercial Schmidt-Cassegrains. Coma may be a problem for wide-field astro-imaging, but these instruments were not designed for such tasks. With Takahashi's field flattener/reducer, these instruments offer superb off-axis images at F/9.

The 250mm and 300mm models have electronic focusing accomplished by moving the secondary mirror. This eliminates the image-shift problem inherent to commercial Schmidt-Cassegrains with moving primary mirrors. Because of the loose tolerances required in moving large and heavy mirrors on a baffle tube, most SCT's will not maintain perfect collimation. Image quality is then compromised in such optical systems. The large Mewlons also have removable covers for their primary mirror cells, this aids in rapid mirror cooling so that the observer can take advantage of favorable seeing conditions more quickly. These features make the large Mewlons ideal for high-resolution CCD imagery.

Mewlon - 300 Dall-Kirkham OTA Specifications

• Effective aperture: 300mm


• Focal length: 3572mm / 2739mm w/ reducer


• Focal ratio: f/11.9 - f/9.1 w/ reducer


• Resolution: 0.40"


• Limiting magnitude: 14.2


• Light grasp: 1837x


• Image circle: 25mm / 40mm w/ reducer


• Photographic field: 45' w/ reducer


• Total length of main tube: 1094mm


• Diameter of main tube: 324mm


• Primary mirror: 310mm f/3


• Seondary mirror: 95mm / x4


• Finder scope: 11x70 6.3 degree


• Gross wt. of main tube assembly: 26kg (52.7lb)
  

  [UPDATED 03/14/11]
           CAMERA ADAPTERS                            CONFIGURATION

  CANON EOS DIGITAL SLR**	TMW0004 EOS WIDE MOUNT T-RING ADAPTER + CAMERA
  NIKON DIGITAL SLR	TMW0001 NIKON WIDE MOUNT-T-RING ADAPTER + CAMERA
  SBIG CFW-8/9 + ST CAMERA	TCD0012 + CAMERA
  SBIG CFW-10 + ST CAMERA	TCD0012L+ CAMERA
  SBIG  ST SERIES W/O FILTER WHEEL/ST-2000 SBIG ST-402ME, 1603, 3200	TCD0327 + CAMERA   TCD0385 + CAMERA
  SBIG STL CAMERA SBIG STL + FW8-STL SBIG ST8300 SBIG ST8300 + FW5 OR FW8	TCD0012STL + CAMERA TCD0012S + CAMERA TCD0385 + CAMERA TCD0165 + CAMERA
  FLI CFW 1,2 PROLINE SERIES FLI CFW 1,2 MICROLINE SERIES	TCD0012FLI-1 + CAMERA TCD0012FLI-2 + CAMERA
  STARLIGHT XPRESS + TRUE TECH FILTER BOX	TCD0075 + CAMERA
  STARLIGHT XPRESS SXVF H9C OR M25C OR M26C	TCDO385 + CAMERA
  QSI 500 SERIES WS & WSI	TCD0204 + CAMERA
  QSI 500 SERIES WSG 2.156” QSI 500 SERIES WSG T-MOUNT	TCD0774 + CAMERA TCD0001 + CAMERA
  LUMENERA SKY nyx	TCD0385 + CAMERA
  QHY-8	TCD0350 + CAMERA
  ORION STARSHOOT	TCD0327 +  CAMERA

   

   * ADAPTERS AVAILABLE FOR OTHER DIGITAL SLR’s QSI 500

  56mm* BACK FOCUS: FS-60C FLATTENER AND .73x REDUCER

   

  *THE 56mm BACK FOCUS IS MEASURED FROM THE REAR OF THE THREADED END            OF THE REDUCER /FLATTENER RATHER THAN FROM THE SHOULDER

   

  SBIG CFW-8/9 + ST CAMERA	TCD0023 + CAMERA
  SBIG CFW-10 + ST CAMERA	TCD0025 + CAMERA
  ATIK 383L	TCD0385 + CAMERA