Takahashi FCT-L 0.8x Focal Reducer
CHF 817.46
Takahashi FC-100DF telescope with a 100 mm fluorite doublet, native focal length of 740 mm at f/7.4, and a 50.8 mm rack. Optical tube only configuration, part number TFK10110.
CHF 2'398.00incl. Swiss VAT
Part Number TFK10110
Will be ordered for you
Delivery time: 5 to 7 business days
Estimated shipping: Between November 23 and 24, 2026
The Takahashi FC-100DF is a 100-mm apochromatic refractor designed for astronomical observation and photography. Its air-spaced doublet features an internal fluorite lens and a hard multi-layer coating. The native focal length of 740 mm corresponds to an f/7.4 ratio.
The 50.8-mm sliding rail allows for the mounting of compatible visual and photographic accessories. The tube measures 785 mm with a fixed anti-fog shield, and its outer diameter is 95 mm.
The 76D-FL corrector, the FC/FS MFL1.04X multi-flattener, and the 76D-RD and FC-35RD reducers are available as options. With the FC-35RD, the focal length increases to 480 mm at f/4.8, resulting in a corrected image circle of 44 mm. Takahashi specifically recommends this reducer for APS-C sensors or larger.
The diagram for the selected corrector specifies the connections and the distance from the sensor that must be maintained for this eyepiece.
Takahashi FC-100DF optical tube, part number TFK10110, with objective lens and focuser. Be sure to select a mount and adapter suitable for the complete assembly, as well as the accessories you need for your specific use.
Takahashi FC-100DF Specifications and 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.
95 mm clamps compatible with the FC-100DF. Check the number of clamps included and make sure to use a mounting plate that fits your mount.
Choose the PrimaLuce PLUS Vixen 240 mm tail if your mount has a Vixen clamp. Use the recommended PrimaLuce PLUS clamps, sold separately. Check the length, spacing, and balance. Also check the clearance for the eyepiece holder and accessories. An alternative to the Losmandy version.
PrimaLuce PLUS Losmandy 240 mm tail—choose this if your mount has a Losmandy clamp. Use with the recommended PrimaLuce PLUS clamps, sold separately. Check the length, spacing, and balance. Also check the clearance for the eyepiece holder and accessories. An alternative to the Vixen version.
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.
