Takahashi Visual Coupling L Adapter

Product Overview

The Coupling (L) is the long version of the coupling ring Takahashi supplies with several of its refractors — a plain mechanical ring, no lens or mirror, with a published 20 mm light path. That is twice the 10 mm of the Coupling (S) it sits beside on the system charts, where it carries no. 14L.

Who It's For

This is a good match if a visual train comes up short of focus with the standard coupling in place, or if you are building a second train and want the longer of the two from the start.

Key Features & Design

• Coupling (L) — Takahashi part TKP00104: the long member of Takahashi's M55.9 coupling pair, listed as no. 14L.
• 20 mm light path: ten millimetres more than the Coupling (S), which is often enough to push a diagonal and eyepiece out to where they come to focus.
• Solid one-piece construction: nothing to adjust or align.

Recommended Uses

Use it to join a diagonal, extension tube or eyepiece holder into Takahashi's 50.8 mm accessory sleeve system where the shorter Coupling (S) leaves the train sitting too far inside focus.

Compatibility and Accessory Notes

It mates with the same M55.9 accessory chain as the Coupling (S), and the two thread into the same places — choosing between them is a question of how much length your train needs, nothing more. The 20 mm figure is what this ring adds to your optical path rather than something you would take off the part with calipers, and the Takahashi Back Focus Guide lists it alongside the back focus target for each Takahashi telescope.

Frequently Asked Questions

Is it difficult to set up?

No — it threads straight into the accessory chain it was designed for.

How does it differ from the Coupling (S)?

Length, and nothing else. The S is TKP00103 at 10 mm; this one is TKP00104 at 20 mm.

Does it change magnification or add optical power?

No — it is a mechanical spacer, and its only effect on the train is the 20 mm it occupies.

Bottom Line

The 20 mm coupling from Takahashi's M55.9 pair, for visual trains that need more length than the 10 mm Coupling (S) gives them. If you are not certain which of the two your telescope wants, send us the model and the rest of the train and we will work it out with you.