This extension tube is used to mount the extender-Q1.6x on the Takahashi FS-60 refractor (and SKY-90 or old FSQ-106 refractors). It provides the necessary extension to obtain the 1.6x ratio behind the extender. It has M42x0.75 threads (female to male) and the net spacing distance is 40 mm.
The inlet and outlet reference surfaces are shown on the schematic half-section of the Characteristics section.
| Characteristic | Takahashi Vari-tube (L) 61-A |
| Item number | TKA00586 |
| Input mechanical interface | M42x0.75 thread (T-mount), female |
| Output mechanical interface | M42x0.75 thread (T-mount), male |
| Spacing distance | 40 mm |
| Size | Length 45 mm, diameter 47 mm |
| Weight | 45 g |
