Common Equipment Standards
This page is intended to hold information about commonly used standards for equipment used by amateur astronomers.
Eyepiece Formats
There are three common formats for eyepieces based on the diameter of the eyepiece's barrel flange and the focuser's receptacle. These are typically described using imperial standard measures.
0.965 inch
1.25 inch
2 inch
Threads
| Common Name | Specification* | Common Uses | Notes |
|---|---|---|---|
| T2 | M42x0.75 | (Need info here) | |
| SCT Thread | 2"x1/24" (50.8x1.058 mm) | SCT visual backs | Typically found on the back of Schmidt-Cassegrain telescopes for attaching a visual back. |
| C-Mount | 1"x1/32" (25.4x0.794 mm) | Camera lens mounts | Often used to attach lenses to cameras where a proprietary connection is not used (e.g. Nikon or Canon lens mounts). Usually has a back-focus distance of 17.526 mm. |
| CS-Mount | 1"x1/32" (25.4x0.794 mm) | Camera lens mounts | Similar to C-Mount, but usually has a back-focus distance of 12.526 mm. |
| 1.25" Filter Thread | M28.5x0.5 | Commonly used for attaching filters to 1.25" eyepieces. | Some manufacturers use a 0.6 thread pitch. |
| 2" Filter Thread | M48x0.6 | Commonly used for attaching filters to 2" eyepieces. | Some manufacturers use a 0.75 thread pitch. |
| Camera Tripod Thread | 1/4"x20 (6.35x1.27 mm) | Attaching cameras to tripods | Found on most DSLR and other consumer cameras as well as many small telescopes and other items. |
| Larger Camera Tripod Thread | 3/8"x16 (9.53x1.5875 mm) | Attaching larger cameras to tripod | Commonly found on medium and large format cameras. Also used by the ZWO SeeStar Smart Telescopes. |
- If the specification is not normally given in metric, metric is included in parentheses.
