Takahashi FSQ-106EDX4 4.2" F/5 Dual ED/Four Element Optical Tube


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This Takahashi FSQ-106EDX4 quadruplet is the ultimate portable no-compromise photo/visual refractor . . .
Our Product #: FSQ106X
Takahashi Product #: TQE10630
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Product Description

The Takahashi FSQ-106EDX4 quadruplet is a redesign of the FSQ-106, the workhorseof the Takahashi imaging refractor line. Its redesigned four-element double ED element modified Petzval optics have been optimized for imaging as well as visual applications. It is measurably the best no-compromise portable photo-visual refractor Takahashi has ever built, and they've built a lot of very good scopes over the years.

The FSQ-106ED is a 4.2" aperture f/5 (530mm focal length) four-lens photo/visual system using two ED (Extra-low Dispersion) glass elements. Based on the classic two-doublet Petzval design, the FSQ-106ED takes full advantage of the latest exotic glass types to produce levels of correction for coma, astigmatism, field curvature, secondary spectrum, spherical aberration, and spherochromatism that are unsurpassed - even better than their legendary fluorite scopes.

This Telescope's Optical System . . .

  • Apochromatic modified Petzval refractor optical system: 4.2" aperture f/5 (530mm focal length) four-lens fully-multicoated system using two ED (Extra-low Dispersion) glass elements. The modified Petzval design uses a true apochromatic doublet objective lens with an ED element to gather the light. For most telescope manufacturers, this would be enough. But Takahashi goes a step further to perfect your observing and imaging experience. There is a second widely air-spaced ED doublet within the focuser drawtube itself. This second doublet optimizes the optical wavefront from the objective lens to eliminate any residual astigmatism. It also acts as a field flattener for wide field astrophotography. The result is a very wide and flat field with high contrast images that are without any hint of lateral color. Color correction has been extended to 1000nm, well into the infrared, to produce non-bloated photographic star images
  • Large Image Circle: At prime focus the 88mm image circle covers a huge swathe of the sky measuring 9.5° in diameter. The large image circle will fully illuminate any 35mm, 645, or 6x7 medium format film camera; any vacuum back roll film holder; or any of the large format commercial grade CCD cameras available now or in the near future. Light fall-off is minor. The field is 90% illuminated at a 53mm diameter (a 35mm negative and the largest currently available SBIG Research Series chip measure only 44mm across their diagonals). It is still 67% illuminated at the edges of the 88mm image circle, an illumination that is easily compensated for with a CCD imager by a simple flat field.
  • Long Back Focus: The generous back focus of 178mm allows the user to attach a variety of imaging packages, binoviewers, 2" star diagonals, and many other visual devices. The 178mm back focus has been designed to handle the ever-larger image trains of CCD imaging experts - electric focusers or temperature compensated focusers, flip mirror systems, filter wheels, adaptive optics systems, etc.
  • Optional Focal Extender: If you need a slower system, an optional 1.6x 2" Extender-QE designed specifically for the new FSQ-106EDX4 converts the f/5 scope to a more high magnification-friendly f/8 system. It provides a 44mmm image circle with a 3° field of view.

This Telescope's Mechanical System . . .

  • Compact Optical Tube: The all-aluminum 125mm diameter scope body is finished in ivory, with black trim, and is very solidly built. Knife-edge baffles within the tube block off-axis light for high contrast and dark sky backgrounds. The tube length of only 16.7" with the dew shield retracted allows the "Q" to be highly airline-transportable. Even when the dew shield is extended the total length is only 20.5". 
  • Focuser: The focuser is a new ultra-duty 4" rack-and-pinion design with both 2" and 1.25" eyepiece adapters. The focuser has a silky-smooth motion and oversize knobs that make it easy to achieve sharp focus, even at very high powers. The focuser includes a 10:1 ratio Micro Edge fine focuser for critical high magnification and photographic focusing.
  • Camera angle adjuster: The focuser includes a new built-in camera angle adjuster/rotator that will carry a 5kg (11 lb.) load to handle the weight of the new large chip CCD cameras and their associated accessories.
  • Dew shield: The optical tube has a retractable self-storing dew shield. A thumbscrew locks the dew shield in place, either when extended or when retracted. The dew shield serves the dual purpose of retarding the formation of dew during long observing sessions and improving the photo/visual contrast, much as a camera lens shade does.

Tech Details

Aperture 4.2"
Focal Length 530mm
Focal Ratio f/5
Highest Useful Magnification 212x
Weight 15 lbs.
Resolution 1.09 arc seconds
Telescope Type Refractor
Visual Limiting Magnitude 11.9
Warranty 5 years


Review by:
I don't have this scope, but i keep dreaming about getting one, i saw enough results to know that this is the one i want to get in future, top class high end quality refractor, nothing less from Takahashi, and this is one of their gems anyway, i hope to get this scope in my life, definitely very highly recommended. (Posted on 10/31/2019)
Review by:
I started imaging a few years back and struggled with reducers and flatteners on my first couple of refractors. Those require exact spacing and are additional lenses that really need to be figured for the scope they will go on to work the best. I also found that my first refractors didn't have the best focusers. The truth is that while they weren't the best for imaging, they worked well enough to learn all the things it takes to get good images. I finally sold those on Cloudy Nights to fund the purchase of the Tak FSQ-106EDX4. You can see and feel the quality of the FSQ-106 from the first time you open it. It has a large, fully corrected image circle that will work with large camera sensors. There is nothing you need to add. The 4" focuser works smoothly and I added a Rigel nSTep auto focuser for auto focusing. There is also a camera angle adjuster that comes with the scope. It makes rotating the whole imaging train easy . This is one of those scopes that I will keep forever. It just works and the optics are excellent.
I want to thank Astronomics for running and supporting the CN site. It is my goto site for equipment and processing information. It is also a great way to buy and sell used astro equipment. We are lucky to have a company like Astronomics that provides this great service to the amateur astronomy community. (Posted on 10/4/2019)
Review by:
Having owned an FSQ-106EDXIII for several years, I can say that it (and the FSQ-106EDXIV) are the ideal imaging scope for large nebulae, galaxies and galaxy chains (e.g., M31, M33, M101, Virgo Cluster). While not cheap by any means, the scope is a tremendous value proposition given the substantial price jump to the recently discontinued FSQ-130. With an enormous imaging circle, you can say goodbye to vignetting. The optics are simply top notch. No more pulling your hair out after long nights imaging when you realize your subs suffer from coma, chromatic aberration, field curvature or any of the other seemingly innumerable problems suffered by sub-par imaging OTAs. A few notes. The native f/5 is the scope's sweet spot. However, there are multiple options, including the 1.6x extender, the 0.73x reducer and the 645 reducer. The backspacing requirements for the reducers and extenders demand precise spacers and adapters so be careful when taking camera manufacturers' specs at face value. The level of exactitude is high and may require some experimentation. The stock focuser is fine for visual use but can benefit greatly with one of the high-end third-party focusers, e.g., the Moonlite of FLI offerings, when imaging. Given that this is an astrograph designed for imaging, keep in mind that consistent, razor-sharp focus may require one of these given the Taks susceptibility to temperature changes throughout the night. You will not be disappointed with the FSQ-106ED. (Posted on 7/22/2019)
Review by:
i remember reading an article in wired magazine a few years back on top astrophotographers. almost every one had some sort of monster aperture RC *and* and FS 106. perfect scope for wide field imaging and of course visual work. (Posted on 8/4/2017)
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