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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.

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Omegon 2“ Extension tube, 35mm optical path
Omegon
2“ Extension tube, 35mm optical path
$ 29.90
ready for shipping in 24 h
Omegon 1.25'', 30mm extension tube
Omegon
1.25'', 30mm extension tube
$ 19.90
ready for shipping in 24 h
Omegon 2'' - 1.25'' Twist-lock adapter
Omegon
2'' - 1.25'' Twist-lock adapter
( 5 / 5 )
$ 79.00
ready for shipping in 24 h
Omegon 2'' extension tube with 50mm optical path
Omegon
2'' extension tube with 50mm optical path
$ 39.90
ready for shipping in 24 h
ASToptics M54 (Female) to M48 (Male) adapter
ASToptics
M54 (Female) to M48 (Male) adapter
$ 30.90
ready for shipping in 24 h
Explore Scientific Extension tube M48 set
Explore Scientific
Extension tube M48 set
$ 57.00
ready for shipping in 24 h
Omegon T2 to 1.25'' adapter
Omegon
T2 to 1.25'' adapter
$ 29.90
ready for shipping in 24 h
Omegon 2'' extension tube, 80mm optical path
Omegon
2'' extension tube, 80mm optical path
$ 49.90
ready for shipping in 24 h
Omegon 2'' Twist-lock adapter
Omegon
2'' Twist-lock adapter
$ 99.00
ready for shipping in 24 h
Omegon T-Adapter M54(m)/T2(m)
Omegon
T-Adapter M54(m)/T2(m)
$ 24.90
ready for shipping in 24 h
Artesky Adapter Twist Lock 2" (Skywatcher Newton)
Artesky
Adapter Twist Lock 2" (Skywatcher Newton)
$ 103.00
Product can be shipped as of 01.02.2025
Baader ClickLock 2" to 1.25" reducer adapter
Baader
ClickLock 2" to 1.25" reducer adapter
( 5 / 5 )
$ 86.00
ready for shipping in 24 h
ASToptics Extension tube M48 Fine tuning Kit - 0.5mm; 0.8mm; 1mm
ASToptics
Extension tube M48 Fine tuning Kit - 0.5mm; 0.8mm; 1mm
$ 25.90
ready for shipping in 24 h
Omegon 40mm T2i/T2a T2 extension ring
Omegon
40mm T2i/T2a T2 extension ring
$ 24.90
ready for shipping in 24 h
PegasusAstro Adapter M54 Male - M54 Male
PegasusAstro
Adapter M54 Male - M54 Male
$ 30.90
ready for shipping in 1-2 weeks
ZWO T2 / C mount adapter
ZWO
T2 / C mount adapter
$ 25.90
ready for shipping in 24 h
Baader Extension tube Hypoerion Finetuning ring 28mm
Baader
Extension tube Hypoerion Finetuning ring 28mm
$ 20.90
ready for shipping in 1-2 weeks
ASToptics M42 (FEMALE) TO M42 (FEMALE) adapter, 10MM
ASToptics
M42 (FEMALE) TO M42 (FEMALE) adapter, 10MM
$ 25.90
ready for shipping in 24 h
Omegon 7.5 mm T2i/T2a T2 extension ring
Omegon
7.5 mm T2i/T2a T2 extension ring
$ 19.90
ready for shipping in 24 h
Baader Adapter Focusing T-2 eyepiece clamp 1 1/4 "
Baader
Adapter Focusing T-2 eyepiece clamp 1 1/4 "
$ 47.90
ready for shipping in 1-2 weeks
ASToptics Extension tube T2 Fine tuning Kit - 0.5mm; 0.8mm; 1mm
ASToptics
Extension tube T2 Fine tuning Kit - 0.5mm; 0.8mm; 1mm
$ 25.90
ready for shipping in 24 h
ASToptics Extension Tube M48 Filter thread - 4mm Length
ASToptics
Extension Tube M48 Filter thread - 4mm Length
$ 20.90
ready for shipping in 24 h
ASToptics Extension tube M48 - Filter thread - 5mm long
ASToptics
Extension tube M48 - Filter thread - 5mm long
$ 20.90
ready for shipping in 24 h
Baader T2/1.25" ultrashort adapter
Baader
T2/1.25" ultrashort adapter
$ 31.90
ready for shipping in 1-2 weeks
ASToptics T2 ADAPTER FOR TELEVUE POWERMATE 2.5X/5X
ASToptics
T2 ADAPTER FOR TELEVUE POWERMATE 2.5X/5X
$ 52.00
ready for shipping in 24 h
Baader Extension tube Hyperion Finetuning ring 14mm
Baader
Extension tube Hyperion Finetuning ring 14mm
RRP:  $ 17.90
Our price:
$ 15.90
ready for shipping in 1-2 weeks
ASToptics 72mm to M48 adapter, 2"
ASToptics
72mm to M48 adapter, 2"
$ 15.90
ready for shipping in 24 h
ASToptics M48(M) to 1.25" filter(F) adapter
ASToptics
M48(M) to 1.25" filter(F) adapter
$ 15.90
ready for shipping in 24 h
Omegon 15mm T2i/T2a T2 extension ring
Omegon
15mm T2i/T2a T2 extension ring
$ 24.90
ready for shipping in 24 h
Omegon Extension tube Extender 30 mm T- thread
Omegon
Extension tube Extender 30 mm T- thread
$ 29.90
ready for shipping in 24 h
ASToptics 1.25" eyepiece to 0.965 focuser adapter
ASToptics
1.25" eyepiece to 0.965 focuser adapter
$ 35.90
ready for shipping in 24 h
ASToptics M56x0.75 (F) to M48x0.75 (M) adapter
ASToptics
M56x0.75 (F) to M48x0.75 (M) adapter
$ 30.90
ready for shipping in 24 h
ASToptics M54*0.75 - 5MM extension ring
ASToptics
M54*0.75 - 5MM extension ring
$ 30.90
ready for shipping in 24 h
ASToptics M56(M) to M48(F) adapter
ASToptics
M56(M) to M48(F) adapter
$ 30.90
ready for shipping in 24 h
ASToptics T2 extension tube - 7mm long
ASToptics
T2 extension tube - 7mm long
$ 20.90
ready for shipping in 24 h
ASToptics T2 extension tube - 6mm long
ASToptics
T2 extension tube - 6mm long
$ 25.90
ready for shipping in 24 h