Takahashi FC-76DCU 76mm f/7.5 Fluorite Doublet Refractor OTA

Product Overview

The FC-76DCU is Takahashi's 76 mm fluorite doublet apochromat — a step up in aperture from the FS-60 line, in a tube with a fixed 80 mm barrel and a retractable dew shield that extends to 95 mm. At 570 mm focal length and f/7.5 it runs 656 mm long and weighs 1.7 kg, and it ships with a working set of visual couplings and adapters rather than a bare tube.

Who It's For

This is a good match if you want more aperture and focal length than a 60 mm refractor offers, in a tube that still packs down for travel with its retractable dew shield. It suits visual observers who want brighter, higher-resolution views of the moon and planets than a 60 mm scope delivers, and imagers who want a mid-aperture apochromat that reduces and flattens cleanly for deep-sky framing.

Key Features & Design

• Air-spaced fluorite doublet: two elements in two groups, the same fluorite-crystal design language as the rest of Takahashi's FC/FS range, scaled to 76 mm.
• 570 mm at f/7.5: more aperture and reach than the FS-60 line, still a compact travel-length tube.
• 159 mm of back focus: enough room for a diagonal, filter wheel or imaging train.
• Retractable dew shield: extends to 95 mm over an 80 mm tube, and collapses for transport.
• 30 mm drawtube extension on a rack-and-pinion focuser.
• Included couplings: ships with a visual adapter, aux ring, eyepiece adapter and camera couplings — a working visual train out of the box.
• 1.7 kg: light enough for mid-sized equatorial and travel mounts.

Optical / Mechanical Design

The objective is a two-element, air-spaced fluorite doublet, the same design family as the FS-60 and FS-60Q but built to a 76 mm aperture. Fluorite's anomalous partial dispersion keeps the red, green and blue focal points close enough together that the two-element design controls colour the way a more complex triplet would at this size, and hard multicoatings on the fluorite surface protect it and cut internal reflections.

The 159 mm of back focus is what makes the FC/FS MFL 1.04x flattener and the 76D RD NC 0.85x reducer usable on this tube — both reach focus within the published spacing, turning the same objective into either a flat 590 mm f/7.8 imaging setup or a faster 486 mm f/6.4 wide-field configuration.

Recommended Uses

• Visual observing: lunar, planetary and double-star work at 570 mm and f/7.5, with more resolution than a 60 mm aperture.
• Flat-field deep-sky imaging: with the FC/FS MFL 1.04x flattener at 590 mm and f/7.8, corrected to a 44 mm circle.
• Wide-field imaging: with the 76D RD NC 0.85x reducer at 486 mm and f/6.4.
• Travel and eclipse observing: the retractable dew shield keeps the packed length manageable.

Compatibility and Accessory Notes

The FC-76DCU's system chart, plus its Extender-C2X and Extender-Q charts, are in the Downloads tab and list every adapter and distance for each configuration. Our Takahashi Back Focus Guide collects the same figures for the whole range.

• Back focus: 159 mm at prime focus.
• Field flattener: FC/FS MFL 1.04x — 590 mm, f/7.8, 44 mm circle, 75.0 mm back focus.
• Focal reducer: 76D RD NC 0.85x — 486 mm, f/6.4, 44 mm circle, 56.0 mm back focus.
• Included in the box: Visual Adapter (TKP20005), Coupling L (TKP00104), Aux Ring (TKP20001), Eyepiece Adapter (TKP00101) and Coupling DT (TKP20006B) — a visual train ready to accept a 1.25-inch diagonal and eyepiece.
• Mount: sold as an OTA — no mount, rings or dovetail included. At 1.7 kg it suits mid-sized equatorial and travel mounts.

If you are planning an imaging train and want to confirm spacing before ordering, send us your camera and filter setup and we will work it out with you.

Good to Know Before You Order

• This is an optical tube assembly. Mount, tripod, rings and dovetail are sold separately, though the visual couplings needed for an eyepiece are included.
• A flat field for imaging needs the flattener or reducer. At prime focus the field curves, as on any doublet refractor.
• The FURD 0.64x reducer is built for the longer-tube FC-76DP, not this one. The DCU uses the 76D RD NC 0.85x reducer instead.

Frequently Asked Questions

Is it difficult to set up?

No — it ships with the visual couplings needed for a diagonal and eyepiece, and the system chart in the Downloads tab lists every part and distance for imaging configurations.

What is it best used for?

Visual observing of the moon and planets at 76 mm aperture, and deep-sky imaging once the flattener or reducer is fitted.

What is the difference between the FC-76DCU and FC-76DP?

Same 76 mm objective and 570 mm native focal length, different tube. The DCU has a shorter, retractable-dew-shield tube at 159 mm back focus; the DP is a longer fixed tube with 207.1 mm of back focus for its own dedicated FURD reducer.

Does it need a flattener for astrophotography?

At prime focus, yes, for a flat field to the edge — the MFL 1.04x flattener or the 0.85x reducer each correct it.

What comes in the box besides the tube?

A visual adapter, aux ring, eyepiece adapter and two couplings — enough to attach a 1.25-inch diagonal and eyepiece without buying additional adapters.

Bottom Line

In short: a 76 mm fluorite doublet apochromat at 570 mm and f/7.5, with 159 mm of back focus, a retractable dew shield, and the couplings needed for visual use included — ready to flatten or reduce for imaging when you add the matching corrector.