For Epsilon-180ED users who want to shoot at longer focal lengths than the native 500mm, Takahashi offers a 1.5x extender. The focal length increases to 770mm and the aperture ratio to F/4.3.This extender is specific to the hyperbolic Newtonian optical formula of the Takahashi Epsilon-180ED; it cannot be used on another telescope.
It includes 7 lenses, divided into 5 groups. The coma is fully corrected on an image circle of 44 mm in diameter which covers the full frame. As shown on the spot-diagram, the diffraction spot measures 2 microns in the center of the field and 5 microns on the periphery.
The Takahashi ε-Extender E-180ED can be used for both visual and photographic purposes; refer to the system-chart for assemblies. The input mechanical interface is M68 x 0.75 male thread. The output is M54 x 0.75 female. Mounting a camera is direct, with the addition of a Takahashi wide field T-ring specific to your camera brand. Although possible, the use of 2" filters (with M48 thread) screwed into the extender is not recommended. They can cause unsightly reflections. Also, due to the construction of the extender, it is no longer possible to screw these filters into the wide field T-ring, as is usually allowed. Any filters must therefore be attached either directly to the camera (as a clip to be placed directly in front of the sensor), or in a filter wheel in the case of a camera.
| Characteristic | Takahashi 1.5x ε-Extender E-180ED |
| Focal length | 770 mm |
| Focal ratio | F/4.3 |
| Image circle diameter | 44 mm |
| Metal back distance | 56.2 mm |
| Telescope | Takahashi Epsilon-180ED |
| Caractéristique | Takahashi 1.5x ε-Extender E-180ED |
| Design | 7 lenses (5 groups) |
| Input interface | M68x0.75 male thread |
| Output interface | M54x075 female thread |
| Backfocus length | 45.2 mm |
| Mechanical diameter | 78.5 mm |
| Total length | 105.5 mm |
| Weight | 550 g |
