DARK CLEAR SKIES · IMAGING ACCESSORIES
Add 20 mm.
Keep your T2 connection.
A fixed M42 × 0.75 extension tube with male and female threads, for adding a defined length to a compatible imaging train.
The DCS M42 × 0.75 Extension Tube – 20 mm adds 20 mm of specified back-focus spacing between compatible T2-threaded components. It is a practical spacer when your camera and accessories need additional separation to meet the spacing requirement of an optical corrector, reducer or flattener.
Three details to match
- Thread: M42 × 0.75, also known as T2.
- Connections: male at one end and female at the other.
- Added spacing: 20 mm.
Plan the spacing in your imaging train
Camera sensor distance, filter wheels, off-axis guiders and adapters all contribute to the distance behind an optical corrector. This fixed-length tube provides a 20 mm section within that assembly while retaining the same T2 thread size.
Check the spacing specified for your exact optical accessory, then account for the components already installed. The 20 mm figure is the tube’s specified back-focus contribution, as stated on its product label; use that figure when planning the spacing between the mating components.
Compatibility and fitting
The M42 × 0.75 male end screws into a matching T2 female connection, while the M42 × 0.75 female end accepts a matching T2 male connection. Check both the diameter and pitch on the parts you are joining.
Use matching 0.75 mm-pitch components. Photographic M42 × 1 connections use a different pitch and require a suitable adapter, as do M48 or M54 connections. Check available thread clearance and the total spacing of your assembly before use.
Specifications
| Brand | Dark Clear Skies |
|---|---|
| Product type | Fixed threaded extension tube |
| External connection | M42 × 0.75 male (T2) |
| Internal connection | M42 × 0.75 female (T2) |
| Specified back-focus spacing | 20 mm |
| Finish | Black, with Dark Clear Skies engraving |
| SKU | DCS-M42-EXT-20 |
What’s included
One DCS M42 × 0.75 extension tube with 20 mm specified back-focus spacing. Cameras, optical correctors and additional adapters are sold separately.
Choosing your extension
Browse our telescope adapters and extension tubes for other connections and lengths. If you need help matching a spacer, tell us the exact components you are connecting and the back-focus distance you need to achieve.