Takahashi 2" Adapter for FSQ85-ED

Product Overview

Takahashi's 50.8 Adapter for the FSQ-106EDX4 and FSQ-85EDX (TKP27110S) slides inside the existing focuser drawtube on these two telescopes to accept 2-inch eyepieces and diagonals. It's also required on the FSQ-106EDX4 when the 1.6x Extender is fitted, where it supplies the same 2-inch step for that configuration.

Takahashi publishes a light path length of 30 mm for it — shorter than the equivalent adapter for the FS-102/128/130/152 series (40 mm), tuned instead to how these two telescopes are spaced. It's still worth factoring into a backfocus calculation if your train is already close to its limit.

Who It's For

This is a good match if you own an FSQ-85EDX or FSQ-106EDX4 and want to run 2-inch eyepieces or a diagonal directly, or if you're running the 1.6x Extender on the FSQ-106EDX4 and need the matching 2-inch step.

It isn't the same part as the FSQ85 2" Visual Adapter (TKT37110) sold alongside it — that one is built for the Extender-QE 1.6x 2" field flattener system rather than the bare focuser drawtube. See its own listing if that's your setup.

Key Features & Design

• M72 x 1.0 male telescope-side thread: slides inside the FSQ-85EDX / FSQ-106EDX4 focuser drawtube.
• 2-inch (50.8 mm) accessory side: accepts standard 2-inch eyepieces and diagonals.
• Purely mechanical: no optical element, no change to focal length or focal ratio.

Recommended Uses

• Visual observing with 2-inch eyepieces on the FSQ-85EDX or FSQ-106EDX4.
• Fitting a 2-inch diagonal for wide-field visual use.
• Running the FSQ-106EDX4 with its 1.6x Extender, where this adapter supplies the required 2-inch step.

Compatibility and Accessory Notes

• Built for the FSQ-85EDX and FSQ-106EDX4 specifically. The M72 thread is shared with other Takahashi refractors, but the 30 mm light path is tuned to these two.
• Adds 30 mm to the optical path — enough to matter against a flattener's backfocus spec or a tight focuser travel. Our Takahashi Back Focus Guide lists this figure alongside the back focus each telescope needs.

Good to Know Before You Order

• It isn't interchangeable with the Normal Refractors version of this adapter, which runs a longer 40 mm light path built for the FS-102/128/130/152 drawtube. Tell us your telescope model and we'll confirm the right one.

Frequently Asked Questions

Is it difficult to set up?

No — it slides into the existing drawtube and the 2-inch accessory fits straight in.

Which telescopes does it fit?

The FSQ-85EDX, and the FSQ-106EDX4 both on its own and with the 1.6x Extender fitted.

Is this the same part as the FSQ85 2" Visual Adapter?

No — that one is built for the Extender-QE 1.6x 2" field flattener system, a different point in the train with its own listing.

How much does it add to my optical train?

30 mm. Send us your full setup if you want to check it against your backfocus target.

Bottom Line

In short: a 2-inch adapter for the FSQ-85EDX and FSQ-106EDX4's focuser drawtube, adding 30 mm of light path — on its own or with the 1.6x Extender fitted.