Takahashi 2" Extension Tube (L)

Product Overview

Takahashi's Extension Tube (L) (50.8), part TKP31112, is a 2-inch sleeve that lengthens a Takahashi imaging or visual train. Takahashi publishes a light path length of 73.5 mm for it — not its physical size, but what it adds once it's in the train — and it's the longer of Takahashi's two 50.8 mm extension tubes; the shorter Extension Tube (50.8) (TKP27112) adds 62 mm instead.

At 73.5 mm it's a substantial step, useful when a shorter extension leaves you short of focus or short of a flattener's specified backfocus.

Who It's For

This is a good match if your setup needs roughly 73.5 mm of additional 2-inch spacing to reach focus or hit a flattener's specified backfocus — on a TOA-130 imaging train, for instance, where Takahashi lists it as a compatible accessory.

Key Features & Design

• 50.8 mm sleeve: accepts standard 2-inch fittings on both ends.
• 73.5 mm light path length: Takahashi's published figure for the spacing this tube adds.
• Black anodized finish: non-reflective inside the light path.

Recommended Uses

• Reaching focus in trains with a long inward-travel requirement.
• Hitting a flattener or reducer's specified backfocus, where the shorter extension tube falls short.
• Extending a TOA-130 imaging or visual train, where Takahashi lists it as a compatible part.

Compatibility and Accessory Notes

• 50.8 mm sleeve fitting on both ends, compatible with Takahashi's 2-inch accessory system.
• Adds 73.5 mm to the optical path — worth working into a full train calculation before you order. Our Takahashi Back Focus Guide lists it alongside the back focus figures for each telescope.
• Purely mechanical — no optical element, no change to focal length or focal ratio.

Good to Know Before You Order

• It's the longer of two similar Takahashi extension tubes. The shorter Extension Tube (50.8) adds 62 mm rather than 73.5 mm — tell us your target spacing and we'll confirm which one you need.

Frequently Asked Questions

Is it difficult to set up?

No — it's a straight sleeve that fits between two 2-inch fittings, with nothing to align.

How much does it add to my optical train?

73.5 mm — send us your full train if you'd like it checked against a flattener's backfocus spec before you order.

Is there a shorter version?

Yes — Takahashi's Extension Tube (50.8) adds 62 mm instead, sold as a separate part.

Does it include any optics?

No. It's a mechanical adapter only.

Bottom Line

In short: Takahashi's 2-inch Extension Tube (L) — a 50.8 mm sleeve adding 73.5 mm of light path, for trains that need the longer of Takahashi's two standard extension steps.