Takahashi TOA-150 / TSA-120 0.7x TOA-35 Reducer and Camera Ring

Product Overview

The TOA-35 Reducer 150 Set pairs Takahashi's 0.7x TOA-35 reducer with a CA Ring 150 sized for the TOA-150B and TSA-120/TSA-102, cutting these telescopes to a materially faster focal ratio while holding a flat Φ44mm image circle. The reducer is the same 4-element, 3-group optic used across the whole TOA-35 line — this kit's CA Ring 150 is what makes it fit the TOA-150 and TSA-120 mounts specifically, and it's the reason a camera ring is called out explicitly in this listing's title.

Who It's For

This kit suits TOA-150B and TSA-120 (and TSA-102) owners who want a faster imaging focal ratio without leaving the ED apochromat optics those telescopes are built around. On the TOA-150B it lands at f/5.2; on the TSA-120 at f/5.3; on the TSA-102 at f/5.6 — each a substantial step down from the telescope's native focal ratio.

Key Features & Design

• 4 elements in 3 groups: the same optical design used across every TOA-35 reducer kit, with two of the elements in low-dispersion, high-refractive-index glass.
• 0.7x reduction: a 30% cut in focal length on each compatible telescope.
• Φ44mm corrected image circle: flat, sharp field across the reduced focal length — full coverage of APS-C and most 44mm-class sensors.
• Bundled CA Ring 150 ("camera ring"): sized for the TOA-150B and TSA-120/TSA-102 mounts, installed as a matched system rather than sourced separately.

Optical / Mechanical Design

Takahashi builds the TOA-35 as four elements in three groups, two of them in low-dispersion, high-refractive-index glass. It works as a focal reducer and a field corrector at the same time: the 30% reduction in focal length is what makes the telescope faster, and the correction is what keeps a Φ44mm circle flat once it is. Both matter for large-sensor imaging, where the corners are the first place a reducer's limits show.

The reducer threads to the included CA Ring 150. Back focus is 62.5mm on both the TOA-150B and the TSA-120. See the Takahashi Back Focus Guide for the full spacing chain.

Recommended Uses

Faster deep-sky imaging on the TOA-150B, TSA-120 or TSA-102 where exposure time matters — nebulae, galaxies, and clusters that benefit from the reduced focal ratio; general astrophotography where a shorter focal length better frames larger targets.

Compatibility and Accessory Notes

This is the same 0.7x reducer optic used on the TOA-130, but bundled here with the larger CA Ring 150 for the TOA-150 and TSA-120/TSA-102 mounts. TOA-130NS/NFB owners use the sibling kit, the TOA-35 0.7x Reducer for TOA-130, which bundles the identical reducer with CA Ring 130 instead — the two kits are not interchangeable between telescopes even though the optic inside them is the same.

Good to Know Before You Order

Sold as a matched kit: the CA Ring 150 (the "camera ring" in this listing's title) is bundled with the reducer, so there's nothing separate to source for a TOA-150B, TSA-120 or TSA-102.

Back focus is the figure to confirm: the corners are where spacing shows, and the total depends on your camera, filter drawer and any spacers in between. Send us what you are connecting and we will add the chain up with you before you order.

Frequently Asked Questions

Is it difficult to set up?

No — the reducer threads to the included CA Ring 150, sized to install directly on the telescope's mount. The work is in getting the back focus total right, and that is a calculation we are happy to run for you.

What is it best used for?

Deep-sky astrophotography on the TOA-150B, TSA-120 or TSA-102 at a faster focal ratio than the telescope's native configuration.

Is this the same reducer as the TOA-130 kit?

The optic is identical. What differs is the bundled ring — this kit ships with CA Ring 150 for the TOA-150/TSA-120/TSA-102; the TOA-130 kit ships with CA Ring 130 instead.

Will it cover my sensor?

The corrected circle is Φ44mm, which covers APS-C fully and most 44mm-class sensors. Larger full-frame corners fall outside it.

What else do I need with it?

Your camera's own T-ring or adapter to complete the connection at the published back focus figure.

Bottom Line

A matched TOA-35 reducer kit for the TOA-150B and TSA-120/TSA-102, with the CA Ring 150 camera ring included, delivering a flat Φ44mm image circle at f/5.2–f/5.6 depending on the telescope.