Takahashi FS-60CP (OTA)

With the FS-60CP, Takahashi offers an image-oriented variant of its FS-60 compact telescope. The objective remains unchanged (the fluorite doublet of the FS-60CB), but a very high performance focal reducer, called FU RD 0.65x, is proposed to transform the instrument into a true very short focal length astrograph (230 mm, F /D 3.8.) ). The optical and mechanical designs of the latter forced the Japanese manufacturer to completely overhaul the focusing system of the FS-60 and to change the sight output from the 31.75 mm slide to the 50.8 mm slide.

An innovative reducer

The FU 0.65x reducer is an optical innovation. It is composed of 4 lenses, one of which is made of fluorite, a novelty in this type of amateur instrument. It eliminates residual chromatism that could persist with the 0.72X C reducer; chromatic aberration is further reduced by half compared to the previous model. The field is perfectly flat and covers the surface of a 24x36 full frame sensor. The spot radius, 3 µm RMS, is homogeneous from the center of the field to the periphery. The size of the lenses and the change of position of the reducer on the telescope increase the field illumination in focus by about 80%, even at the periphery.

Spotting scope dot diagram Takahashi FS-60CP with FU RD focal reducer 0.65X. Top, RMS radius in mm from spot to focus, from the optical axis to the edge of the field (22 mm from the center), calculated at 11 wavelengths (436 nm to 656 nm). Below, appearance of the spot at the same wavelengths in a 100 µm side box.

Renewed mechanics

The installation of this extraordinary reducer forced Takahashi to significantly rework the mechanical output of the FS-60. The original FS-60 tube is not compatible with this type of accessory which requires the use of a larger and more robust focusing system. In addition, the end of the tube has been replaced by a wider model to which the SKY-90 focuser is attached. This assembly offers the possibility to screw on the reducer (with M64 thread) and natively adapt an eyepiece holder to the 2" (50.8 mm) slide, which was not possible with the FS-60CB.

This change of rear configuration thus gives access to new assemblies, either with 2" slide or with the classic M56 thread. Adapting certain existing accessories sometimes requires modifying an assembly: for example, viewing with the standard FC/FS MFL1 .04X (Multi Flattener) field corrector requires the installation of an L30 extension tube [TKA18006].

The rack and pinion focusing system of the Takahashi FS-60CP scope is oversized. The output integrates a rotating collar for framing photographs (CAA-S) and a 50.8 mm focuser (with 31.75 mm reducer).

The optical tube attachment has also been revised. Double collars and a dovetail type Vixen (optional) replace the one-piece collar. The mounting is made on the wide part of the optical tube. The dovetail is equipped with numerous holes to facilitate balancing, regardless of the imaging train installed at the focus.

The Takahashi FS-60CP telescope with dedicated dovetail and collars (optional).

A high-end astrograph

With the FS-60CP equipped with the FU RD 0.65X reducer, Takahashi offers a high-end alternative to Chinese wide-field astrographs . As usual, the prestigious Japanese brand manages to combine optical performance and impeccable mechanics without compromise.

The telescope is sold in tube only, without accessories. No collars or dovetails are supplied. The FU RD 0.65X field reducer is sold separately.