The Takahashi FC-100DF apochromatic refractor is designed around a fluorite doublet at F/7.4. It is equipped with a 50.8 mm rack-and-pinion focuser, larger than that of the FC-100DC, allowing the mounting of heavier cameras. Its use remains very versatile and even a small mount will make it possible to exploit its full potential.
If you want to make astrophotography at the native focal length of the refractor, a field corrector is available. It can also be equipped with a focal reducer : either the 76D-RD model normally intended for the small focuser, or the FC-35RD model, specific to the FC-100DF and its 50.8 mm focuser. The use of the latter is recommended for cameras or APNs equipped with APS-C or higher sensors.
| Characteristic | Takahashi FC-100DF refractor |
| Objective | Fluorite doublet apochromat |
| Lens cell | Air-spaced doublet. Fluorite in the back |
| Coatings | Hard multicoatings |
| Diameter | 100 mm |
| At prime focus | |
| Focal length | 740 mm |
| Focal ratio | F/7.4 |
| Metal Back Distance | 223 mm |
| With 76D-FL field corrector | |
| Focal length | 770 mm |
| Focal ratio | F/7.7 |
| Image circle diameter | 35 mm |
| Metal Back Distance | 56.2 mm |
| With FC/FS MFL1.04X field corrector | |
| Focal length | 757 mm |
| Focal ratio | F/7.6 |
| Image circle diameter | 44 mm |
| Metal Back Distance | 71.2 mm |
| With 76D RD focal reducer | |
| Focal length | 540 mm |
| Focal ratio | F/5.4 |
| Image circle diameter | 30 mm |
| Backfocus | 56.2 mm |
| With FC-35RD focal reducer | |
| Focal length | 480 mm |
| Focal ratio | F/4.8 |
| Image circle diameter | 44 mm |
| Metal Back Distance | 74.1 mm |
| With EX-Q1.6X focal extender | |
| Focal length | 1185 mm |
| Focal ratio | F/11.9 |
| Metal Bck Distance | 157 mm |
| With C2X focal extender | |
| Focal length | 1480 mm |
| Focal ratio | F/D 14,8 |
| Metal Back Distance | 73 mm |
| Characteristic | Takahashi FC-100DF refractor |
| Length of the optical tube | 785 mm (with fixed dew-shield) |
| Diameter of the optical tube | 95 mm |
| Diameter of the dew-shield | 124 mm |
| Weight | 3.6 kg |
| Focuser | Rack-and-pinion |
Spot-diagram of Takahashi FC-100D refractor at prime focus
Spot-diagram of Takahashi FC-100D refractor with 76D FL field corrector
Spot-diagram of Takahashi FC-100D refractor with FC/FS MFL1.04X field corrector
Spot-diagram of Takahashi FC-100D refractor with FC-35RD focal reducer
| System-chart of Takahashi FC-100DF telescope | Télécharger |
| System-chart of Takahashi FC-100DF refractor with FC-35RD | Télécharger |
| System-chart of Takahashi FC-100DF refractor with Extender Q 1.6X | Télécharger |
| System-chart of Takahashi FC-100DF refractor with Extender C2X | Télécharger |
