Takahashi FCT-L 0.8x Focal Reducer
CHF 817.46
Takahashi FC-100DF 100-mm telescope, focal length 740 mm at f/7.4, 50.8-mm rack. Part number TFK10100, configuration with finder scope and mount.
CHF 2'709.00incl. Swiss VAT
Part Number TFK10100
Will be ordered for you
Delivery time: 5 to 7 business days
Estimated shipping: Between November 23 and 24, 2026
The Takahashi FC-100DF combines a 100-mm apochromatic objective with a native focal length of 740 mm, for an f/7.4 ratio. The air-spaced doublet features an internal fluorite lens and is coated with a hard multicoating.
The 50.8 mm sliding rail allows you to create a visual or photographic display using the appropriate connectors. The tube measures 785 mm with its fixed anti-fog shield.
The 76D-FL corrector, the FC/FS MFL1.04X multi-flattener, and the 76D-RD and FC-35RD reducers are available as options. Takahashi specifically recommends the FC-35RD for APS-C sensors or larger. The choice of adapter rings and the distance to the sensor depends on the specific telescope and corrector selected.
The researcher helps with alignment, while the collar holds the tube in place on a suitable mount.
Choose a mount that is compatible with your equipment, and check that the assembly is balanced and securely fastened.
Takahashi FC-100DF Documentation
The Takahashi FCT-L 0.8x Focal Reducer allows the FC-100DF to be used at 587 mm and f/5.9, with an image circle of 44 mm.
The Takahashi FCT-L 0.99x Field Corrector flattens the field while maintaining a focal length of 734 mm at f/7.3, with an image circle of 55 mm.
These two accessories are sold separately and use the FCT-L CO 100DF ring, which is compatible with the FC-100DF. The kit also includes the Camera Angle Adjuster M. When using the FCT-L 0.99x corrector, the M72 L52 extension tube is required as an additional accessory for the FC-100DF.
For a CMOS camera, select the M72-M48 or M72-M54 end adapter that matches the camera’s connection. The sensor plane must be located 55 mm from the base of the thread on the camera side of this adapter. Refer to the Takahashi diagram for the selected converter for the order of the parts and the necessary connections.
With the FC-100DF, Takahashi notes a slight residual chromatic halo originating from the lens when using either of the two FCT-L converters.
The Takahashi FC-100DF is a 100-mm-aperture fluorite doublet refractor with a focal length of 740 mm (f/7.4), designed primarily for deep-sky astrophotography. Its focal length is ideal for observing galaxies (M51, M101, the Leo Triplet), planetary nebulae such as M27, and globular clusters, with a good level of detail. At f/7.4, its classic aperture-to-focal-length ratio requires slightly longer exposure times, but in return produces very fine star points.
With an APS-C camera featuring 3.76 µm pixels (Sony IMX571 sensor), you get approximately 1.05″ per pixel for a field of view of 1.8° × 1.2°. With the 0.66× crop factor, this increases to 1.59″ per pixel and a field of view of 2.8° × 1.8°.
Yes, whenever you're using an APS-C or full-frame sensor: like any uncorrected doublet lens, it has a slight field curvature that stretches the stars in the corners. Dedicated correctors: Takahashi TKA00582: 1.04x MFL FC/FS Corrector ; Takahashi 76D RD: Focal Reducer for FC Telescopes ; Takahashi TKA19580 - FC-35 0.66× focal reducer (equivalent focal length of 488 mm, f/4.9); Takahashi FCT-L 0.8x Focal Reducer (equivalent focal length of 592 mm, f/5.9); Takahashi FCT-L 0.99x Field Corrector.
223 mm (metal back); 71.2 mm with MFL 1.04×; 74.1 mm with FC-35RD 0.66×; 55 mm with FCT-L 0.99×/0.8×. This focal length is measured from the thread to the sensor, including rings, filter wheel, and filter drawer: adhering to this measurement down to the millimeter ensures that stars remain round in the corners.
The tube weighs about 3.6 kg; with the camera, filter wheel, and guide scope, expect it to weigh around 5.1 kg: an HEQ5-R Pro-class mount provides plenty of headroom. A refractor requires no collimation: once balanced, it’s ready to use as soon as it reaches operating temperature. At 78.5 cm long, it fits easily in the trunk.
Yes, as a bonus: with an angled mirror and an eyepiece, it provides high-contrast, color-accurate images of the Moon, the planets, and double stars, up to about 200× magnification.
Here are a few accessories we've selected for this model, depending on your needs.
Extender-Q 1.6× to increase the focal length and magnification. Check the connections according to the Takahashi diagram; the 50.8 mm TKA00596 adapter may be required depending on the mount.
120 mm heating strip for a 124 mm defogger. Check its location and clearance; a 12 V power supply or controller with an RCA connector and sufficient power must be provided separately.
Recommended diameter: 125 mm. Check the measurement and the mounting.
Recommended diameter: 150 mm. Check the measurement and the mounting.
