{"id":20305,"date":"2026-10-23T16:32:16","date_gmt":"2026-10-23T14:32:16","guid":{"rendered":"https:\/\/deep-space-astronomy.ch\/?post_type=product&p=20305"},"modified":"2026-10-28T20:40:04","modified_gmt":"2026-10-28T19:40:04","slug":"reducteur-focale-takahashi-fct-l-08x","status":"publish","type":"product","link":"https:\/\/deep-space-astronomy.ch\/en\/product\/reducteur-focale-takahashi-fct-l-08x\/","title":{"rendered":"Takahashi FCT-L 0.8x Focal Reducer"},"content":{"rendered":"

The Takahashi FCT-L 0.8x focal reducer is designed for astrophotography with the FCT-114DF, FCT-114DS, FC-100DZ, and FC-100DF refractors. Its three-element, two-group optical design shortens the focal length while correcting stellar images within a 44-mm image circle. It allows for a more open photographic system, with particular attention paid to star shape and field illumination.<\/p>\n

A configuration tailored to each pair of glasses<\/h3>\n

With the FCT-114DF and FCT-114DS, Takahashi announces a focal length of 639 mm at f\/5.6. The FC-100DZ reaches 636 mm at f\/6.4, while the FC-100DF operates at 587 mm at f\/5.9. These values correspond to the specifications provided by the manufacturer. Compatibility depends on the entire mounting assembly, including the CO ring designed for the telescope and the adapter for the camera.<\/p>\n

Choosing the right ring is essential: the FCT-L CO 114D is compatible with the FCT-114DF, FCT-114DS, and FC-100DZ, while the FCT-L CO 100DF is designed for the FC-100DF. These rings, sold separately, have different optical path lengths. The adapter uses an M72 male thread with a 1 mm pitch on each side. Installation also requires the M-series camera rotator, in accordance with the Takahashi diagram.<\/p>\n

Stellar Luminosity and Quality<\/h3>\n

At the edge of full format, the reported relative illumination is approximately 92 % with the FCT-114DF, 83 % with the FCT-114DS and the FC-100DZ, and 82 % with the FC-100DF. For the FCT-114D models, the RMS spot diameter is 4.4 \u00b5m on-axis and 6.6 \u00b5m at the edge of the full-frame area. The FC-100DF retains a slight chromatic halo from its lens; the reducer therefore does not completely eliminate this optical characteristic.<\/p>\n

Connecting the Camera<\/h3>\n

For a CMOS camera, select the M72-to-M48 or M72-to-M54 adapter that matches its connection. The sensor must be positioned 55 mm from the base of the thread on the camera side of this adapter. For a Canon EF or Nikon F camera body, the setup uses the M72 WR adapter and the appropriate DX-WR ring. These components are separate from the step-down adapter. The diagram also calls for the use of filters, with a caveat from the manufacturer: they may cause unwanted reflections and vignetting.<\/p>\n

Technical specifications<\/h3>\n
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Function<\/th>\n0.8x focal length reduction<\/td>\n<\/tr>\n
Compatible glasses<\/th>\nFCT-114DF, FCT-114DS, FC-100DZ, FC-100DF<\/td>\n<\/tr>\n
FCT-114DF \/ FCT-114DS<\/th>\n639 mm, f\/5.6<\/td>\n<\/tr>\n
FC-100DZ<\/th>\n636 mm, f\/6.4<\/td>\n<\/tr>\n
FC-100DF<\/th>\n587 mm, f\/5.9<\/td>\n<\/tr>\n
Image circle<\/th>\n44 mm<\/td>\n<\/tr>\n
Optical package<\/th>\n3 lenses in 2 groups<\/td>\n<\/tr>\n
Fittings<\/th>\nM72 \u00d7 1 male on both the eyepiece side and the camera side<\/td>\n<\/tr>\n
Dimensions<\/th>\n\u00d8 78 \u00d7 59.5 mm<\/td>\n<\/tr>\n
Mass<\/th>\nAbout 560 g<\/td>\n<\/tr>\n
CO Ring, Separate<\/th>\nCO 114D: FCT-114DF \/ FCT-114DS \/ FC-100DZ; CO 100DF: FC-100DF<\/td>\n<\/tr>\n
CMOS Print<\/th>\n55 mm from the base of the thread on the camera side of the M72-M48 or M72-M54 adapter<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

Compatible glasses in the catalog<\/h3>\n