Like the TSA-120, which has exactly the same optics, the TSA-120FT is equipped with an triplet ED apochromatic lens with a diameter of 120 mm and F/7.5 focal ratio, mounted in a 3-group cell. The latter ensures good stability of the optomechanical chain in the face of the usual constraints of transport and in the face of significant variations in temperature of use. It is equipped with a retractable dew shield.
The lens has been designed to achieve a very high level of performance in observation and photography. The chromatic aberration in short wavelengths (blue and violet) is reduced by one third compared to the old FS-102/FS-128 with Fluorite lens. The Strehl ratio at optimal wavelengths of human vision is almost perfect, at 99.2%, equivalent to that of the TOA series.
The TSA-120 is therefore a lightweight, compact and economical refractor, whose performance is similar to that of the TOA, Takahashi's flagship models and recognized as among the best in the world.
On this TSA-120FT version, the original focuser is replaced by a Starlight Instruments Feather Touch 3.0" model engraved "Made for Takahashi", equipped with a 1/10 microfocuser. The adaptation has been optimised so that the accessory mounts remain identical to the original version. The oversized focuser allows for robust assemblies with large cameras and filter wheels.
The addition of the optional field corrector allows native focus imaging. The TOA-35 reducer (F/5.25) makes it more comfortable in deep sky photography. All assemblies meet the rigidity and flexibility requirements of new imaging devices, such as digital cameras and the latest generation of CCD cameras.
Characteristic | Takahashi TSA-120FT refractor |
Optical design | ED Triplet Super ApochromatD |
Lens cell | Air-spaced triplet. 3 lenses/3 groups. 1 S-FPL53 ED lens in the middle. |
Coatings | Hard multicoatings |
Diameter | 120 mm |
At prime focus | |
Focal length | 900 mm |
Focal ratio | F/7.5 |
Metal back distance | 227.5 mm |
With TOA-35FL field corrector | |
Focal length | 882 mm |
Focal ratio | F/7.3 |
Image circle diameter | 40 mm |
Metal back distance | 117.5 mm |
With TOA-35RD focal reducer | |
Focal length | 672 mm |
Focal ratio | F/5.6 |
Image circle diameter | 40 mm |
Metal back distance | 62.5 mm |
With EXT-ED1.5X focal extender | |
Focal length | 1350 mm |
Focal ratio | F/11.3 |
Image circle diameter | 44 mm |
Metal back distance | 117.5 mm |
Characteristic | Takahashi TSA-120FT refractor |
Length of the optical tube | - |
Diameter of the optical tube | 125 mm |
Diameter of the dew shield | 160 mm |
Weight | 6.7 kg |
Focuser | Starlight Instruments Feather Touch 3.0'' rack-and-pinion focuser |
System-chart of Takahashi TSA-120FT refractor | Télécharger |
Instruction manual of Takahashi TSA-120FT refractor | Télécharger |