Περιγραφή
The Takahashi FCT-65D is a three-lens apochromatic refractor telescope with a fluorite crystal (CaF₂) center element, designed to offer maximum optical performance in a minimum footprint. It is an ultra-compact telescope, designed to meet the needs of modern digital astrophotography, particularly with high-resolution sensors up to the full-frame 24×36 mm format.
Precision optics with fluorite lens
The FCT-65D’s optical group is an air-spaced triplet apochromatic lens, composed of three elements, one of which is made of calcium fluorite. This natural crystal has an extremely low dispersion index, which allows for superior color correction compared to traditional special glass.
The result is top-notch image quality: the polychromatic Strehl ratio reaches 97.5% on-axis, with spherical aberration and residual chromatic aberration virtually imperceptible even with very demanding modern sensors. Contrast is extremely high, and stars appear pinpoint-like right to the edges of the field.
Photographic performance: FU 0.65x reducer and Multi-Flattener
The Takahashi FCT-65D is designed to give the best in astrophotography, thanks to the compatibility with two fundamental accessories:
FU 0.65x focal reducer (optional)
- Specially designed for the FCT-65D.
- It screws inside the focal tube.
- It increases the focal length from 400mm to 260mm, with a focal ratio of f/4.
- Full coverage of the 24×36 mm full-frame format.
- Star spots contained within 2–3 microns RMS.
- Edge illumination: up to 70%.
This reducer uses 4 lenses, one of which is fluorite, and is the first of its kind for amateur instruments to offer such optical quality.
Multi-Flattener 1.04x (optional)
- Extends the focal length to 416 mm (f/6.4).
- Corrected image diameter: 44 mm.
- Backfocus: 56.2 mm (from Multi CA Ring 65D).
- Field correction without magnification reduction, ideal for high-resolution imaging.
Advanced mechanical design
The optical tube has a mechanical structure optimized for the integration of the 0.65x FU reducer. The rear section has been deliberately widened to 95 mm to accommodate the reducer internally, while also improving the stability and rigidity of the entire assembly.
Mechanical characteristics:
- Optical tube length: 403 mm
- Tube outer diameter: 95 mm
- Lens hood diameter: 80 mm
- OTA weight: 1.9 kg
- 2″ eyepiece holder with 1.25″ self-centering reducer
- High-precision rack-and-pinion focusing
- CAA camera rotator included as standard
Compatible accessories (optional)
- Pair of 95mm aluminum rings
- Vixen/GP type dovetail bar
- FU 0.65x reducer
- Multi-Flattener 1.04x
