Takahashi FSQ 106n Refractor

John A. Blackwell
johnb@regulusastro.com

The Takahashi FSQ106n

Arrival:

The telescope was ordered from Anacortes Telescope & Wild Bird and was received within three days. It was well packed in heavy, double layered cardboard with styrofoam endpieces. Unfortunately, the unit had been jostled enough to cause the styrofoam to break down a bit and scatter throughout the box, including regions internal to the tube assembly itself. This was easily cleaned off with a light touch and a wisp of air from a lens bulb.

People often say that first impressions matter a lot. This was such a case. The scope is smaller than I thought, though really tough looking. Indeed, it is only 20" long when shipped with its retractable dewshield in the retracted state. The telescope comes with adapters for a straight through 1.25" eyepiece. There is no star diagonal, no finderscope, no photo equipment, no mounting rings. All of that is extra, in the long tradition of Takahashi equipment.

Upon closer inspection, the first real noticeable difference between this scope and other more traditional refractors is the focuser. It is a huge 4" diameter! That is a lot of light output over a large area. This scope was built with medium format astrophotography in mind. Also integral to the focuser is a heavy duty focus lock and a 360 degree rotating head. The last item allows for precise rotational alignment of a CCD imager or camera.

The Four Inch Focuser

The design of the telescope is of a modified Petzval Refractor. There are two sets of doublets, one for the objective and another very close to the focuser end of the system. Users should beware of possibly scratching this back lens assembly with attempts to use barlows with long tubes. Takahashi does make a lot of available extra equipment for the FSQ106n, including what they call an "Extender-Q" set. This is an inline barlow assembly to make the scope reach an f/8 ratio. This is very useful when observing smaller galaxies and planets.

Stats:

Aperture	106mm
Focal Length	530mm
Focal Ratio	f/5
Lens Elements	Two pairs, Flourite Apochromat modified Petzval design.
Tube Length, Dew Shield Retracted	20"
Tube Length, Dew Shield Extended	24"

The scope has an interesting and well designed retractible dew shield. It slides smoothly from its stored position out to a 4.25" distance away from the objective. This makes the FSQ-106n an ideal scope for travel. All internal surfaces and surfaces coming into contact with the optical path are painted matt black. The tube is knife-edge baffled as one would expect. All optics are multicoated. In fact, when looking down the tube, there are angles one can choose which prevent the lenses from even being seen!

The Objective Lens

Not included in the OTA package is a finder scope, nor the various accessories used to mount cameras and imagers. There is a 1.25" visual back. That is all. Available are a 1.25" star diagonal, a dedicated 2" star diagonal, a various rings and adapters for common cameras and CCD imagers. You will need to order all of these separately. By the time you are done, expect to pay an additional $400 or more on the final purchase, easily. As a minimum, plan to obtain mounting rings for the scope as required by your mount. I used a pair of Parallax rings which mount to the Losmandy Universal Dovetail Plate.

On the G11 mount

First Light:

First Light with this telescope was a magnificent event. Many times I have encountered new equipment and was just satisfied. Rarely am I truly surprised. The Losmandy G-11 and the Van Slyke Slider are two other examples of extraordinary equipment. This Takahashi is the third really remarkable piece of equipment I have bought.

Star images are pinpoints with a remarkable amount of contrast. Side by side with a well-collimated Celestron 8 (which others have also noted as an exceptional model), the FSQ-106n was sharper in focus and had better, rounder and more defined diffraction rings. Splitting Epsilon Lyra was not an issue. I used the Extender Q (1.6x) and a 3mm TeleVue Radian. The stars showed a clearly split pair of double stars with blackness between them. But this was not intended as a visual scope only. Its true power is in astrophotography and CCD imaging. I bought it for the latter, understanding that I would probably never use it to its full potential with a medium format film camera.

The Results:

The following images were taken the first night I attempted imaging with the FSQ 106n. Focus was easily achieved and locked into place. Only minor adjustments were needed throughout the night to compensate for temperature changes. Click on the image to see a full-sized version with exposure data.

M-20, The Triffid Nebula, LRGB image. SBIG ST-7, CFW-8. L:8min R:4min G:4min B:8min.

M-16, The Eagle Nebula, Monochrome image. SBIG ST-7. 6 minutes.

M-8, The Lagoon Nebula, LRGB image. SBIG ST-7, CFW-8. L:10min R:4min G:4min B:8min.

M-17, The Swan Nebula, Monochrome image. SBIG ST-7. 5 minutes.

NGC 6522 and HII 200, Globular Clusters in Sagittarius, Monochrome image. SBIG ST-7. 3 minutes.

Contents	What's Up	Feature	Papers	Photos
	Links	Observations	Spectra	Sketches

	M-20, The Triffid Nebula, LRGB image. SBIG ST-7, CFW-8. L:8min R:4min G:4min B:8min.
	M-16, The Eagle Nebula, Monochrome image. SBIG ST-7. 6 minutes.
	M-8, The Lagoon Nebula, LRGB image. SBIG ST-7, CFW-8. L:10min R:4min G:4min B:8min.
	M-17, The Swan Nebula, Monochrome image. SBIG ST-7. 5 minutes.
	NGC 6522 and HII 200, Globular Clusters in Sagittarius, Monochrome image. SBIG ST-7. 3 minutes.