The world of adapters is diverse and not easy to understand. This is due to the wide variety of thread and plug sizes that optics and accessories may have.
In astronomy, two plug sizes have become established, which are often indicated in the old unit inches ("):
- 1.25" corresponds to 31.8 millimetre
- 2" corresponds to 50.8 millimetres
Many eyepieces, but also cameras, have connectors in one of these two sizes, which can be inserted into the telescope’s focuser.
If a 1.25" connector is to be inserted in a focuser with a 2" connector, a 1.25"/2" adapter is required. This is an example of a reducer adapter: where a connection is reduced from a larger size to a smaller one. The reverse is called an extension adapter.
Another very important category of adapters is camera adapters. These are used to connect cameras to optics or to accessories. The T2 thread (M42x0.75), which enables a screw connection, is very well established for this purpose. Lighter cameras without many accessories can also be easily connected to the telescope via a socket.
For astrophotography it is important that the aperture is large enough to illuminate the sensor (no vignetting) and the optical length matches the focal point.

Omegon
2“ Extension tube, 35mm optical path
$ 29.90

Omegon
Camera adaptor T2-Ring compatible with Canon EOS
$ 19.90

Omegon
Adaptors T-2 to 1.25 nosepiece
$ 19.90

Omegon
2'' - 1.25'' Twist-lock adapter
$ 79.00

Omegon
Camera adaptor T2-Ring für Nikon
$ 19.90

Omegon
2'' extension tube with 50mm optical path
$ 39.90

Omegon
1.25'', 30mm extension tube
$ 19.90

Omegon
2'' extension tube, 80mm optical path
$ 49.90

Omegon
Syncfocus flip-mirror (for planetary cameras)
$ 69.00

Omegon
Camera adapter 1.25"
$ 24.90

Explore Scientific
Extension tube M48 set
$ 63.00

ASToptics
M54 (Female) to M48 (Male) adapter
$ 34.90

Omegon
Adaptors Adapter of 2'' on T2, optical path only 3 mm
$ 34.90

Omegon
2'' Twist-lock adapter
$ 99.00

Omegon
M43 / T2 T-adapter
$ 19.90

Omegon
T2 to 1.25'' adapter
$ 29.90

Omegon
Extension tube 45mm Extender 2''
$ 29.90

Omegon
40mm T2i/T2a T2 extension ring
$ 24.90

ASToptics
Extension tube M48 Fine tuning Kit - 0.5mm; 0.8mm; 1mm
$ 28.90

Omegon
flip mirror
$ 119.00

ASToptics
Extension Tube M48 Filter thread - 4mm Length
$ 22.90

Omegon
2'' to 1.25" reducer adapter
$ 39.90

Omegon
Adaptors 1.25'', 30mm extension tube
$ 24.90

Omegon
Adapter T-Adaptors M54(m)/T2(m)
$ 24.90

Baader
ClickLock 2" to 1.25" reducer adapter
$ 95.00

Artesky
Adapter Twist Lock 2" (Skywatcher Newton)
$ 113.00

Celestron
T-adapter for C5, 6, 8, 9.25, 11, 14
$ 32.90

Omegon
2'' adapters with reducer 1.25 ''
$ 29.90

PegasusAstro
Adapter M54 Male - M54 Male
$ 34.90

Omegon
Nosepiece 2" ver 2 (M48 to 2")
$ 24.90

Omegon
T2 extension tube - 30mm
$ 19.90

Omegon
Cronus T2 Adapter
$ 24.90

Baader
T2/1.25" ultrashort adapter
$ 36.90

Omegon
Adapter 2'' T2 Adaptors with 1.25'' Reducer
RRP:
$ 64.80
Our price:
$ 49.90

Omegon
7.5 mm T2i/T2a T2 extension ring
$ 19.90
