Review - Takahashi FSQ-85ED/EDX/EDP

The Takahashi FSQ-85ED is a Modified Petzval quadruplet apochromat refractor [Image Credit: Takahashi].

Specifications

Aperture:  3.3 in. [85mm]

Focal Length @ Prime Focus:  17.7 in. [450mm]

Focal Ratio @ Prime Focus:  f/5.3

Image Circle @ Prime Focus:  44mm

Photographic Field @ Prime Focus :  5.6°

Focal Length w/ Reducer:  12.9 in. [328mm]

Focal Ratio w/ Reducer:  f/3.86

Image Circle w/ Reducer:  44mm

Photographic Field w/ Reducer:  7.0°

Focal Length w/ Extender:  26.6 in. [675mm]

Focal Ratio w/ Extender:  f/8.0

Image Circle w/ Extender:  44mm

Limiting Magnitude:  ~ 11.8

Resolving Power:  1.36 arc seconds

Lowest Useful Magnification:  12x

Highest Useful Magnification:  170x

Tube Diameter:  3.7 in. [95mm]

Tube Length:  14.5 in. [368mm]

Weight:  8.6 lb. [3.9 kg]

Field of View and Magnification

Monoviewing:

TeleVue 41mm Panoptic: 5.9° @ 11x

TeleVue 31mm Nagler: 5.3° @ 15x

TeleVue 22mm Nagler: 4.0° @ 21x

TeleVue 17mm Nagler: 3.1° @ 27x

TeleVue 12mm Nagler: 2.2° @ 38x

TeleVue 11mm DeLite x Baader Planetarium 1.25″ 2x Carl Zeiss Abbe Barlow x 2: 0.4° @ 164x

Binoviewing:

TeleVue 24mm Panoptic x 2: 2.8° @ 23x

TeleVue 18.2mm DeLite x 2: 1.9° @ 31x

TeleVue 13mm DeLite x 2: 1.4° @ 43x

TeleVue 11mm DeLite x 2: 1.2° @ 51x

Introduction

In 1998, I purchased what I then believed to be the finest compact 3" apochromatic refractor available - the Takahashi FCT-76. At the time, it had almost every feature that I desired in a high-quality portable telescope: a beautifully crafted Optical Tube Assembly [OTA] that was light in weight and machined with top notch fit and finish, incredibly well-corrected optics, a diverse assortment of observing and photographic configurations, and an affordable price [~ $1,650 USD while available].

Fast forward a decade, and there have been very few telescopes of similar size that have come close to rivaling this excellent refractor - until now. Meet the finest 3" apochromatic refractor available today, the Takahashi FSQ-85ED.

Design

The simplest way to explain what makes the Takahashi FSQ-85ED the best 3" refractor around is this - it is a fundamental redesign and improvement of what was lacking in the FCT-76.

For starters, the FCT-76 was not very easy to use with 2" eyepieces right out of the box. This was a function of the telescope's tube length being longer than what was required to bring 2" eyepieces to focus without additional visual adapters. By contrast, the FSQ-85ED tube is over 4" shorter, allowing all 2" eyepieces and binoviewers to be paired with its generous 200mm of available back focus.

Another FCT-76 drawback that has now been corrected in the FSQ-85ED was the length of its dew shield, which was quite short and allowed in stray light interference from nearby homes and street lights. With the FSQ-85ED, this is no longer a problem. The sliding dew shield equals the size of those found on the discontinued FCL-90 and FS-78 models, adequately blocking out light from unwanted sources. When retracted, the overall length of the telescope is just under 15 inches.

A design similarity between the FCT-76 and the FSQ-85ED that really makes for more enjoyable observing or photographic sessions is that both are equipped with large rack-and-pinion focusers to provide greater stability with heavier loads. The FCT-76 focuser is actually more similar to the original FSQ-106ED than the FSQ-85ED, in that the entire focuser rotates.  With the FSQ-85ED, the focuser is fixed but comes with a Camera Angle Adjuster [CAA] to provide for the optimal placement of eyepieces and cameras. Additionally, the FSQ-85ED utilizes a 1:7 ratio micro focuser knob on the right side that assists in dialing in the precise focal point.

Optically, the extra-low dispersion [ED] quadruplet Petzval design offers a fast focal ratio with a very corrected flat field of view. It's difficult to say which telescope performs better at canceling out chromatic aberrations as both are outstanding at doing so. And like the FCT-76, the FSQ-85ED offers high-contrast, razor-sharp views of objects assisted by it's well-baffled OTA.

A Pelican 1510 Protector Case will provide the proper protection for road and air travel.

Modifications

I'm foregoing the use of the Takahashi 2" Ocular Adapter [# TKP27110S] that shipped with the telescope in favor of Baader Planetarium's assortment of 1.25" and 2" adapters.

One such adapter is the 2" Clicklock Eyepiece Clamp [# 2956272]. Designed for Takahashi focusers with 72mm female threaded couplings, the 2" Clicklock Eyepiece Clamp has an innovative rotating locking collar that holds eyepieces and accessories firmly without marring their barrels from thumbscrews or leaving grease impressions from traditional brass locking rings.

A second option to pair optical accessories with the Baby-Q, is the use of a newer silver metal version of the Takahashi Camera Angle Adjuster [CAA-M / TKA23200N]. Included with the purchase of FSQ-85EDX/EDP models, the CAA-M / TKA23200N can be used with the Baader Planetarium 2" Clicklock Eyepiece Clamp when attached on the eyepiece side of the adapter [which is also threaded for 72mm couplings].

Initially, I decided to remove the original green painted Camera Angle Adjuster [CAA / TKA23200] that came with my 2013 FSQ-85ED to help reduce back-end weight when using heavier 2" eyepieces on the Takahashi Teegul Mount v2 w/ Lapides Modification [an altitude-azimuth mount]. The TKA23200 weighs in at about a pound, and its absence helps to transfer the center of balance forward toward the objective lens. You can still reach focus with 2" eyepieces if you use the Baader Planetarium 2" Clicklock Eyepiece Clamp attached to either the CCA / TKA23200 or CAA-M / TKA23200N, but the accessory chain gets a bit long for my taste.

Instead of ditching a Camera Angle Adjuster altogether, I've opted for substituting the Baader Takahashi Adapter M72/M68 (Zeiss) [# 2558230] and the Baader Ultrashort 2" Eyepiece Clamp [# 2458196] for use with the CAA-M / TKA23200N. This shortens things a bit and makes reaching focus with the largest 2" TeleVue Panoptic, Nagler or Ethos eyepieces hassle-free.

In this configuration, it's possible to use the Baader Planetarium 2″ 90° Astro Amici-Prism Diagonal [# 2456120] for correct-image monoviewing with low-to-medium power eyepieces. At higher powers, this diagonal can struggle with maintaining image integrity depending on the quality of your telescope's optics. With the FSQ-85ED, I see a slight drop-off in contrast above 60x. Below that, it's pretty fantastic observing objects as nature intended - especially with this telescope.

For higher power monoviewing, I switch to the Baader Planetarium 2″ Clicklock Dielectric Mirror Diagonal [# 2956100], which provides a traditional image-reversed view. This diagonal is comparable to the Astro-Physics 2" MaxBright Dielectric Mirror Diagonal in optical quality, except that it's lighter and has the Clicklock clamping mechanism. Since the FSQ-85ED has a short focal length of 450mm, you'll need to come up with a way to reach the maximum usable magnification of around 170x [equivalent to 20x per centimeter of aperture or 20 x 8.5cm].

I do this by stacking barlows; specifically, by adding two Baader Planetarium 1.25″ 2x Carl Zeiss Abbe Barlows [CZAB] in front of a TeleVue 11mm DeLite Type 1, which produces 164x magnification. The nice thing about the CZAB is that it happens to be one of the best [if not the best] 1.25" barlows to ever be produced. It's also very short when compared to other high-quality barlows, so there isn't a lot protruding up from the eyepiece side of the diagonal.

When using the Baader Planetarium MaxBright II Binoviewer and a T-2 / 90° 1.25" Amici-Prism with BBHS coating, additional in-focus travel is required and the Camera Angle Adjuster must be removed. In this configuration, standard use of 1.25" eyepieces with the MaxBright II's 1.25x Glasspath Corrector or by adding the Baader Planetarium 1.25″ 2x Carl Zeiss Abbe Barlow [CZAB] at 2.5x magnification comes into play. The latter is accomplished by placing one CZAB directly into the MaxBright II Binoviewer in front of each of the eyepieces.

Imaging

Takahashi uses a 1.01x Field Flattener for the FSQ-85ED to reduce field curvature when using full frame DSLR, CCD, and CMOS cameras.

The QB 0.73x Reducer for full frame imaging yields a 7.0° field of view at f/3.86.

On the flip side, Takahashi also makes an Extender ED 1.50x to increase the focal length of the telescope, which is used to assist in framing smaller celestial objects.

Observing

Unfortunately, a detailed report from West Texas has been delayed again.  I've observed with the FSQ-85ED from the McDonald Observatory on three occasions since 2013, but need to do a methodical review. My next trip is scheduled for late May 2025.

Alternatives

Is it unfair to say that there is no real competition for the FSQ-85ED in the market place today? Well, no it isn't. There are several manufacturers that make excellent 3"apochromatic refractors that do some of the things the FSQ-85ED can; however, none produce all of the outstanding features that Takahashi does.

A caveat to this statement would be the newly released and already sold out of production Astro-Physics 92mm f/6.65 Stowaway. I actually placed my name on the contact list for the telescope 10 years ago and had the opportunity to buy one, but passed due to it's longer f-ratio.

While not quite the bang-for-buck value that the FCT-76 was in 1998 - if you're used to having the best, this is it.

Priced ~ $4,280 USD.

FSQ-85ED System Chart.pdf

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FSQ-85ED Instruction Manual.pdf

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