Takahashi TPL-9 Plossl Eyepiece

Product Overview

The TPL-9 is a 9mm eyepiece from Takahashi's TPL Plossl series, the successor to the older Abbe and LE lines. It uses a 4-elements-in-2-groups Plossl design built with high-refraction, low-dispersion glass, giving a 48° apparent field of view and 6.5mm of eye relief. It weighs 70g and uses the standard 31.7mm (1.25”) barrel.

Who It's For

This is a good match if you want a mid-to-high power eyepiece for planetary detail, lunar craters, and closer double stars, with more forgiving eye relief than the shortest focal lengths in the series.

Key Features & Design

• 4-element, 2-group Plossl design: the current evolution of Takahashi's Plossl line, replacing the older Abbe and LE series.
• High-refraction, low-dispersion glass: Takahashi states this cuts chromatic aberration at the center of the field to roughly half the level of the Abbe series and two-thirds that of the LE series.
• Multilayer coatings at 99% transmission: keeps the image bright across the four elements.
• Matte-finished interior: reduces stray light and internal reflections for better contrast.
• 48° apparent field of view and 6.5mm eye relief at this focal length.

Optical / Mechanical Design

Takahashi describes the TPL series as sharp from the center out to roughly halfway across the field, with only mild star distortion at the corners on its own — and notes that pairing a TPL eyepiece with the 2x Ortho Barlow (sold separately) measurably flattens the field, producing close to full-field correction. At 9mm, the TPL-9 sits mid-range in the series, balancing usable magnification against comfortable eye relief.

Recommended Uses

On a Takahashi TSA-120 (900mm, f/7.5) the TPL-9 gives about 100x, a solid all-around planetary magnification. On a Takahashi FS-60CB (355mm, f/5.9) the same eyepiece yields roughly 39x, useful for brighter deep-sky targets on a small travel refractor. Divide any Takahashi tube's focal length by 9mm for the magnification on your own setup.

Compatibility and Accessory Notes

The 31.7mm (1.25”) barrel fits any Takahashi focuser, star diagonal, or 2″-to-1.25” adapter in the current lineup. Takahashi's own literature notes that combining a TPL eyepiece with the 2x Ortho Barlow improves flat-field performance across the whole view — worth considering if you already use a Barlow in your kit or are deciding whether to add one.

Good to Know Before You Order

Not parfocal: a refocus is needed when swapping the TPL-9 in from another eyepiece in your case.

Frequently Asked Questions

Is it difficult to set up?

No — it threads directly into a standard 1.25” focuser or diagonal.

What is it best used for?

Mid-to-high power visual observing — planetary detail, lunar craters, and double stars.

How does it compare to the Starbase OR-9mm?

Both are 9mm, 4-element eyepieces with a 1.25” barrel. The TPL series uses Takahashi's higher-refraction, low-dispersion glass and multilayer coatings rated at 99% transmission, positioning it a step up from the Starbase budget line at a correspondingly higher price.

What telescopes does it fit?

Any Takahashi refractor or reflector with a standard 1.25” focuser or diagonal.

Bottom Line

A 9mm Plossl eyepiece with a 48° field, 6.5mm eye relief, and a 70g weight — a mid-to-high power option in Takahashi's TPL series, built around high-refraction, low-dispersion glass. If you're building a full eyepiece set and want help matching focal lengths to your telescope, send us your setup and we'll work it out with you.