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Takahashi - Mewlon 250 Dall-Kirkham Optical Tube Assembly - DISCONTINUED

Model#: TLK2500

Discontinued Product

Manufactured by: Takahashi

Details

This is a discontinued item. We recommend the AG Optical 12.5" Dall Kirkham Telescope as a replacement.

Takahashi - Mewlon 250 Dall-Kirkham OTA

 

  • The Mewlon combines refractor-like performance in a larger folded optic reflector design.
  • The 250 optical tube assembly has 9.8" of aperture and a focal ratio of 12.
  • Comes with Fraulhaber German electric focus motor for secondary (no image shift!)
  • OTA includes 7X50 finder, dovetail holder, and tube weight.
  • Photo shows optional mount and tripod not included

 

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

The EM-200 mount (sold separately or in the Mewlon-250 US System Package) provides a stable, accurate platform for the M-210. 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 aides 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.

With the Mewlon series, one doesn't have to sacrifice optical performance for high portability. The Mewlon 250 weighs only 28lbs (12.7kg) and is remarkably compact for a 10" Cassegrain. This instrument is highly portable and offers deep sky views that are exceptional. On the planets, many observers have reported seeing details they thought impossible with telescopes of this aperture. With the exception of a few diffraction spikes around bright stars, on might believe they were observing with a large apochromatic refractor. The advantage, though, is a greater amount of light grasp and resolution than a comparably priced refractor. Indeed, the Mewlons offer an exceptional value in their aperture class.

So if you desire a professional grade instrument in a compact, lightweight package or are tired of compromising light grasp for crisp detail and contrast, check out the Mewlon Cassegrains by Takahashi. You will be pleasantly surprised by their performance.

 


    • [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

       

       

Product Series

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 aides 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.

With the Mewlon series, one doesn't have to sacrifice optical performance for high portability. The 8.3" Mewlon 210 weighs just 18lbs (8.2kg) with a 7x50 finder attached. The Mewlon 250 weighs only 28lbs (12.7kg) and is remarkably compact for a 10" Cassegrain. Both of these instruments are highly portable and offer deep sky views that are exceptional. On the planets, many observers have reported seeing details they thought impossible with telescopes of this aperture. With the exception of a few diffraction spikes around bright stars, on might believe they were observing with a large apochromatic refractor. The advantage, though, is a greater amount of light grasp and resolution than a comparably priced refractor. Indeed, the Mewlons offer an exceptional value in their aperture class.

So if you desire a professional grade instrument in a compact, lightweight package or are tired of compromising light grasp for crisp detail and contrast, check out the Mewlon Cassegrains by Takahashi. You will be pleasantly surprised by their performance. For further analysis of the Takahashi Mewlon Series of Dall-Kirkham Cassegrains, please read Jean Dragesco's review in his book High Resolution Astrophotography, Cambridge University Press, 1995.

Additional Information

Name Takahashi - Mewlon 250 Dall-Kirkham Optical Tube Assembly - DISCONTINUED
Manufacturer Takahashi
Model TLK2500
Discountinued Yes
Aperture 250mm
Diameter 280mm
Finderscope 7x50 6.3 degree
Focal Length 3000mm / 2307mm w/ reducer
Focal Ratio f/12-f/9.2 w/ reducer
Image circle 21mm / 42mm w/ reducer
Light Gathering Power 1275x
Limiting Stellar Magnitude 13.8
Optical Tube Length 850mm
Optical Tube Weight 27.5 Ibs
Photographic field 1.0 degree w/ reducer
Primary Mirror 260mm f/3