When I considered purchasing the Takahashi TSA-120 FTF OTA, I realized that the ED1.5X extender I have for the Takahashi FSQ-85EDX is also compatible with it. That was of course great news.
The TSA-120 has a triplet ED apochromatic lens with a diameter of 120 mm and F/7.5 focal ratio. At prime focus, it has a focal length of 900 mm. With the extender, the focal length is 1’350 mm with a focal ratio of F/11.3.
The weight is 6.3 kg and with that still manageable for me. The Starlight Instruments Feather Touch 3.0” rack-and-pinion focuser is the best I have ever worked with. I chose the FTF version because quite frankly although Takahashi are great telescopes, their focusers could be much better.
Below is a picture of the TSA-120FTF with Extender and a DSLR. It’s also a great telescope for visual observation.
Technical Data Takahashi TSA-120 FTF OTA
| 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 |
Takahashi TSA-120FT refractor
| 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 |
Link to the System Chart
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