The Takahashi FC-100DC apochromatic telescope is designed around a fluorite doublet at F/D 7.4. It is equipped with a 31.75 mm compact rack-and-pinion focuser, inherited from the FS-60CB. It is much lighter than its big sister FC-100DF, only 2.8 kg compared to 3.6 kg for the FC-100DF. A small mount will be enough to make the most of it. Designed primarily for observation, it still allows the use of small cameras in astrophotography.
Photography at the native focal length of the refractor requires the 76D field corrector (or the multi-flattener). The FC-100DC can also be equipped with the 76D-RD focal reducer.
The user of large sensors, in APS-C or higher format, will prefer the FC-100DF model and its dedicated focal reducer, the FC-35RD.
| Caharacteristic | Takahashi FC-100DC 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 | 161 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 |
| Metal Back Distance | 56.2 mm |
| With EX-Q1.6X focal extender | |
| Focal length | 1185 mm |
| Focal ratio | F/11.9 |
| Metal Back 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-100DC refractor |
| Length of the optical tube | 815 mm (with fixed dew-shield) |
| Diameter of the optical tube | 95 mm |
| Diameter of the dew shield | 124 mm |
| Weight | 2.8 kg |
| Focuser | Rack-and-pinion |
Spot-diagram with Takahashi FC-100D at prime focus
Spot-diagram with Takahashi FC-100D with 76D FL field corrector
Spot-diagram with Takahashi FC-100D with FC/FS MFL1.04X field corrector
| System-chart of Takahashi FC-100DC refractor | Télécharger |
| System-chart of Takahashi FC-100DC refractor with Extender Q 1.6X | Télécharger |
| System-chart of Takahashi FC-100DC refractor with Extender C2X | Télécharger |
