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Two threads and one flange distance between camera and sky

The best T-ring adapters for 2026

A T-ring is the piece that lets a camera body sit where an eyepiece would, and it does one job: it converts the proprietary bayonet of a camera into the T2 thread, a standard that almost every telescope accessory maker has settled on. Two things have to match. The camera mount must be the exact bayonet of the body, and mirrorless bodies and reflex bodies of the same brand are not the same fitting. And the flange distance the ring establishes has to be the standard one, because the whole imaging train is measured from the sensor, and a ring that is a millimetre out shifts every calculation made downstream — the spacing of a reducer, the focus reach of a focuser, the field flatness at the corners. That is why an inexpensive ring of unknown tolerance is a poor economy on an otherwise careful setup. Beyond the two threads, read the method of use the adapter is built for. Prime focus, where the telescope acts as the lens and no eyepiece is involved, needs only the ring and a nosepiece or a thread into the focuser. Eyepiece projection, where an eyepiece sits in the path to magnify the image further, needs a longer housing that holds one. Read the internal blackening, and read the material, since an aluminium ring under a heavy body flexes where a steel one does not. We compare camera mount, T2 thread, flange distance, prime focus or projection design, blackening and material.

The parts here, column by column

  1. Bresser T2 camera adapter for 1.25 inch eyepiece projection

    Bresser T2 camera adapter 1.25 in (4940100)

    A projection adapter that takes a 1.25 in eyepiece up to 35 mm in diameter and couples it to a camera through a T2 ring bought separately.

    Camera mount
    T2 — a separate T2 ring for the specific camera is required, as the maker states
    T2 thread
    Not published by the maker.
    Flange distance
    31.7 mm (1.25 in) · 35 mm, as the maker publishes it
    Prime focus or projection design
    Eyepiece-projection adapter — the eyepiece stays in the light path
    Blackening
    Not published by the maker.
    Material
    Not published by the maker.
    Amazon reference
    B001BBE3XW (same reference on 6 Amazon marketplaces)
    EAN
    4007922006604
    • The maker states that a separate T2 ring is required rather than implying it is included
    • Maximum eyepiece diameter is published, which decides whether your eyepiece fits inside
    • Eyepiece projection adds an optic and magnifies more than prime focus does

    Best for: Lunar and planetary photography where extra magnification is wanted

    ≈ £39 / €39
    Check price on Amazon
  2. SVBONY 1.25 inch M42 telescope camera projection adapter

    SVBONY 1.25 in M42 projection adapter

    A 1.25 in projection adapter with an extended 68 mm barrel carrying M42 × 0.75 threads on both the inside and the outside, fully threaded internally against reflections.

    Camera mount
    Canon EOS and Rebel SLR and DSLR with a T2 ring; the maker excludes EOS-M models
    T2 thread
    M42 × 0.75 both male and female
    Flange distance
    68 mm extended, as the maker publishes it
    Prime focus or projection design
    Projection adapter with an extension barrel · 1.25 in
    Blackening
    Fully threaded inside to minimise reflections, per the maker
    Material
    All metal aluminium
    Amazon reference
    B01LWJ2Z3Y (same reference on 5 Amazon marketplaces)
    EAN
    0608560842070
    • Publishes the barrel length, which is what enters the back focus calculation
    • Fully threaded inside, which is a stronger anti-reflection measure than matt paint
    • A 68 mm barrel consumes a great deal of focuser travel

    Best for: Eyepiece projection on a telescope with generous focuser travel

    ≈ £17 / €20
    Check price on Amazon
  3. EBTOOLS Canon EOS T-ring with 1.25 inch telescope coupling

    EBTOOLS T-ring and 1.25 in coupling for Canon EOS

    A set containing a Canon EOS T-ring and a 1.25 in to M42 coupling, with an inner ring that rotates to orient the camera.

    Camera mount
    A long list of Canon EOS and Rebel models is given in the first bullet
    T2 thread
    Not published by the maker.
    Flange distance
    Not published by the maker.
    Prime focus or projection design
    A T-ring for Canon EOS and a 1.25 in to M42 coupling, per the maker · 1.25 in (31.7 mm)
    Blackening
    Not published by the maker.
    Material
    Anodised aluminium
    Amazon reference
    B07JNSHWX7 (same reference on 5 Amazon marketplaces)
    EAN
    0757686467206
    • Both halves of the chain are supplied together, which is rarer than it should be
    • A rotating inner ring lets the camera be squared to the subject without unthreading
    • The compatibility list contains model names that do not resolve, such as “T4ki” and “Rebeliii1”

    Best for: A Canon EOS owner who wants both halves of the coupling in one purchase

    ≈ £15 / €16
    Check price on Amazon
  4. VBESTLIFE 2 inch T2 telescope adapter ring

    VBESTLIFE T2 adapter ring, 2 in

    A 2 in T2 adapter ring in all-metal construction, with an internal surface pattern intended to cut reflections.

    Camera mount
    Not published by the maker.
    T2 thread
    Not stated
    Flange distance
    Not published by the maker.
    Prime focus or projection design
    T2 adapter with a 2 in telescope fitting · 2 in eyepiece diameter, per the maker
    Blackening
    A pattern inside the ring to reduce reflection, per the maker
    Material
    All-metal precision, per the maker
    Amazon reference
    B0824YGXF1 (same reference on 5 Amazon marketplaces)
    EAN
    0738586139776
    • A 2 in fitting rather than 1.25 in, which suits larger focusers and sensors
    • The internal anti-reflection pattern is mentioned rather than ignored
    • No thread pitch, no length, no weight and no clear aperture

    Best for: A 2 in focuser and a T2-threaded camera, where the details will be measured on arrival

    ≈ £13 / €25
    Check price on Amazon
  5. Your Day Mate T2 adapter ring for Canon EF and EF-S in black aluminium

    Your Day Mate T2 adapter ring for Canon EF/EF-S (YODM1-1094)

    A slim CNC-machined T2 ring for Canon EF and EF-S bayonets, with the incompatible Canon systems named outright.

    Camera mount
    Canon EOS with EF and EF-S bayonets
    T2 thread
    T2, named by the maker as M42 × 0.75
    Flange distance
    Not published by the maker.
    Prime focus or projection design
    T-ring — converts the T2 thread to a camera bayonet
    Blackening
    Not published by the maker.
    Material
    CNC-machined black anodised aluminium
    Amazon reference
    B0FR59P92W (same reference on 6 Amazon marketplaces)
    EAN
    4252009210942
    • Names the thread precisely as M42 × 0.75 rather than only as “T2”
    • States which Canon systems it does not fit, which prevents the commonest mistake
    • A T-ring alone does not connect a telescope: a nosepiece or adapter is still needed

    Best for: A Canon DSLR with an EF or EF-S bayonet, at the camera end of an imaging train

    ≈ €10
    Check price on Amazon
  6. YINETTECH T2 to Canon RF mount adapter

    YINETTECH T2 to Canon RF adapter (290-EB)

    An alloy adapter converting the T2 thread to the Canon RF mount, with no glass inside, for EOS R series mirrorless cameras.

    Camera mount
    Canon RF — the EOS R series
    T2 thread
    T2, named by the maker as M42 × 0.75
    Flange distance
    Not published by the maker.
    Prime focus or projection design
    T-ring for a mirrorless mount
    Blackening
    None, stated outright by the maker
    Material
    Alloy
    Amazon reference
    B0G672S7CN (same reference on 6 Amazon marketplaces)
    EAN
    4894833259447
    • States explicitly that it contains no optics, which is the right claim for a mount adapter
    • Covers the RF mount that the EF-only rings on this shelf exclude
    • No thickness figure, which is part of the flange distance arithmetic

    Best for: A Canon EOS R body at the camera end of a telescope imaging train

    ≈ $14 / £14 / €16
    Check price on Amazon
  7. Walimex pro T2 to M42 mount adapter ring

    Walimex pro T2 adapter for M42 mount (23367)

    A mechanical transition ring letting T2-threaded telescopes and accessories be fitted to a camera with an M42 screw mount, with manual focus only.

    Camera mount
    T2 equipment onto an M42-mount camera — the reverse of a standard astronomy T-ring
    T2 thread
    The pitches of the two threads are not published
    Flange distance
    Not published by the maker.
    Prime focus or projection design
    Purely mechanical transition ring, per the maker
    Blackening
    Not published by the maker.
    Material
    Not published by the maker.
    Amazon reference
    B0C6DYVMGG (same reference on 6 Amazon marketplaces)
    EAN
    4056929233674
    • The maker is explicit that it carries no contacts and gives manual focus only
    • Names bellows and microscope adapters as well as telescopes
    • It goes the opposite way from a normal astronomy T-ring, which is easy to misread

    Best for: An M42 screw-mount camera body used with T2 astronomical or laboratory equipment

    ≈ £27 / €20
    Check price on Amazon

Any figure written into the body of this page was true on the day it was written. The amount shown next to each instrument is requested from the retailer as the page loads, and it is that amount, not the text, that stands.