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](/Produktbilder/normal/54437_1/Omegon-2l-Extension-tube-35mm-optical-path.jpg)
Omegon
2“ Extension tube, 35mm optical path
$ 29.90
![Omegon 2'' extension tube with 50mm optical path](/Produktbilder/normal/55072_1/Omegon-2-extension-tube-with-50mm-optical-path.jpg)
Omegon
2'' extension tube with 50mm optical path
$ 39.90
![Omegon 1.25'', 30mm extension tube](/Produktbilder/normal/33231_1/Omegon-1-25-30mm-extension-tube.jpg)
Omegon
1.25'', 30mm extension tube
$ 19.90
![Omegon 2'' adapters with reducer 1.25 ''](/Produktbilder/normal/1044_1/Omegon-2-adapters-with-reducer-1-25-.jpg)
Omegon
2'' adapters with reducer 1.25 ''
$ 29.90
![Omegon extension tube 45mm 2''](/Produktbilder/normal/81073_1/Omegon-extension-tube-45mm-2-.jpg)
Omegon
extension tube 45mm 2''
$ 29.90
![ASToptics Extension Tube - M48 - Filter thread - 10mm Length](/Produktbilder/normal/57633_1/ASToptics-Extension-Tube-M48-Filter-thread-10mm-Length.jpg)
ASToptics
Extension Tube - M48 - Filter thread - 10mm Length
$ 27.90
![ASToptics 2" adapter for 55mm to M48](/Produktbilder/normal/57818_1/ASToptics-2-adapter-for-55mm-to-M48.jpg)
ASToptics
2" adapter for 55mm to M48
$ 16.90
![ASToptics 82mm to M48 adapter (2")](/Produktbilder/normal/57937_1/ASToptics-82mm-to-M48-adapter-2-.jpg)
ASToptics
82mm to M48 adapter (2")
$ 16.90
![William Optics SCT connection for WO Diagonals](/Produktbilder/normal/65327_2/William-Optics-SCT-connection-for-WO-Diagonals.jpg)
William Optics
SCT connection for WO Diagonals
$ 66.00
![ASToptics Easy-Grip Twist-Lock Adapter (2" to 1.25")](/Produktbilder/normal/57894_1/ASToptics-Easy-Grip-Twist-Lock-Adapter-2-to-1-25-.jpg)
ASToptics
Easy-Grip Twist-Lock Adapter (2" to 1.25")
$ 77.00
![Omegon 2'' to 1.25" reducer adapter](/Produktbilder/normal/33229_1/Omegon-2-to-1-25-reducer-adapter.jpg)
Omegon
2'' to 1.25" reducer adapter
$ 39.90
![TeleVue 0.50" Length Accessory Tube for 2.4"](/Produktbilder/normal/19093_1/TeleVue-0-50-Length-Accessory-Tube-for-2-4-.jpg)
TeleVue
0.50" Length Accessory Tube for 2.4"
$ 66.00
![William Optics M63 Adapter für Flattener Flat6AIII](/Produktbilder/normal/72296_1/William-Optics-M63-Adapter-fuer-Flattener-Flat6AIII.jpg)
William Optics
M63 Adapter für Flattener Flat6AIII
$ 66.00
![ASToptics M54 (Female) to M48 (Male) adapter](/Produktbilder/normal/57906_1/ASToptics-M54-Female-to-M48-Male-adapter.jpg)
ASToptics
M54 (Female) to M48 (Male) adapter
$ 33.90
![ASToptics Extension tube M48 Fine tuning Kit - 0.5mm; 0.8mm; 1mm](/Produktbilder/normal/57846_1/ASToptics-Extension-tube-M48-Fine-tuning-Kit-0-5mm-0-8mm-1mm.jpg)
ASToptics
Extension tube M48 Fine tuning Kit - 0.5mm; 0.8mm; 1mm
$ 27.90
![Omegon 2'' extension tube, 80mm optical path](/Produktbilder/normal/54438_1/Omegon-2-extension-tube-80mm-optical-path.jpg)
Omegon
2'' extension tube, 80mm optical path
$ 49.90
![Explore Scientific M48/T2 adapter](/Produktbilder/normal/68621_1/Explore-Scientific-M48-T2-adapter.jpg)
Explore Scientific
M48/T2 adapter
$ 27.90
![Omegon 2'' - 1.25'' Twist-lock adapter](/Produktbilder/normal/45633_1/Omegon-2-1-25-Twist-lock-adapter.jpg)
Omegon
2'' - 1.25'' Twist-lock adapter
$ 79.00
![ASToptics Extension tube Variable M48 extender, 23-29mm](/Produktbilder/normal/57790_1/ASToptics-Extension-tube-Variable-M48-extender-23-29mm.jpg)
ASToptics
Extension tube Variable M48 extender, 23-29mm
$ 77.00
![ASToptics Extension tube M48 - Filter thread - 5mm long](/Produktbilder/normal/57637_1/ASToptics-Extension-tube-M48-Filter-thread-5mm-long.jpg)
ASToptics
Extension tube M48 - Filter thread - 5mm long
$ 22.90
![ASToptics T2 extension tube - 9mm in length](/Produktbilder/normal/57641_1/ASToptics-T2-extension-tube-9mm-in-length.jpg)
ASToptics
T2 extension tube - 9mm in length
$ 27.90
![ASToptics T2 extension tube - 7mm long](/Produktbilder/normal/57672_1/ASToptics-T2-extension-tube-7mm-long.jpg)
ASToptics
T2 extension tube - 7mm long
$ 27.90
![ASToptics T2 extension tube - 30mm](/Produktbilder/normal/57673_1/ASToptics-T2-extension-tube-30mm.jpg)
ASToptics
T2 extension tube - 30mm
$ 33.90
![ASToptics Extension Tube M48 Filter thread - 4mm Length](/Produktbilder/normal/57776_1/ASToptics-Extension-Tube-M48-Filter-thread-4mm-Length.jpg)
ASToptics
Extension Tube M48 Filter thread - 4mm Length
$ 22.90
![ASToptics Extension Tube M48 Filter thread - 7.5 mm Length](/Produktbilder/normal/57777_1/ASToptics-Extension-Tube-M48-Filter-thread-7-5-mm-Length.jpg)
ASToptics
Extension Tube M48 Filter thread - 7.5 mm Length
$ 27.90
![ASToptics Extension Tube M48 Filter thread - 11mm Length](/Produktbilder/normal/57784_1/ASToptics-Extension-Tube-M48-Filter-thread-11mm-Length.jpg)
ASToptics
Extension Tube M48 Filter thread - 11mm Length
$ 33.90
![ASToptics Extension tube T2 Fine tuning Kit - 0.5mm; 0.8mm; 1mm](/Produktbilder/normal/57846_1/ASToptics-Extension-tube-T2-Fine-tuning-Kit-0-5mm-0-8mm-1mm.jpg)
ASToptics
Extension tube T2 Fine tuning Kit - 0.5mm; 0.8mm; 1mm
$ 27.90
![ASToptics Extension Tube M48 - 2" - Filter thread - 16mm Length](/Produktbilder/normal/57843_1/ASToptics-Extension-Tube-M48-2-Filter-thread-16mm-Length.jpg)
ASToptics
Extension Tube M48 - 2" - Filter thread - 16mm Length
$ 38.90
![ASToptics T2 extension tube - 4mm long](/Produktbilder/normal/57864_1/ASToptics-T2-extension-tube-4mm-long.jpg)
ASToptics
T2 extension tube - 4mm long
$ 22.90
![ASToptics T2 extension tube - 6mm long](/Produktbilder/normal/57865_1/ASToptics-T2-extension-tube-6mm-long.jpg)
ASToptics
T2 extension tube - 6mm long
$ 27.90
![ASToptics M54*0.75 - 5MM extension ring](/Produktbilder/normal/57936_1/ASToptics-M54%2A0-75-5MM-extension-ring.jpg)
ASToptics
M54*0.75 - 5MM extension ring
$ 33.90
![Paton Hawksley Extension tube Spacer SA](/Produktbilder/normal/54302_1/Paton-Hawksley-Extension-tube-Spacer-SA.jpg)
Paton Hawksley
Extension tube Spacer SA
$ 22.90
![ASToptics M48(M) to 1.25" filter(F) adapter](/Produktbilder/normal/57665_1/ASToptics-M48-M-to-1-25-filter-F-adapter.jpg)
ASToptics
M48(M) to 1.25" filter(F) adapter
$ 16.90
![ASToptics M56x0.75 (F) to M48x0.75 (M) adapter](/Produktbilder/normal/57885_1/ASToptics-M56x0-75-F-to-M48x0-75-M-adapter.jpg)
ASToptics
M56x0.75 (F) to M48x0.75 (M) adapter
$ 33.90
![ASToptics M42 (FEMALE) TO M42 (FEMALE) adapter, 10MM](/Produktbilder/normal/57912_1/ASToptics-M42-FEMALE-TO-M42-FEMALE-adapter-10MM.jpg)
ASToptics
M42 (FEMALE) TO M42 (FEMALE) adapter, 10MM
$ 27.90
![ASToptics 1.25" eyepiece to 0.965 focuser adapter](/Produktbilder/normal/57678_1/ASToptics-1-25-eyepiece-to-0-965-focuser-adapter.jpg)