DARK CLEAR SKIES · IMAGING ACCESSORIES
Add 20 mm to your M52 setup.
Complete the spacing in your imaging train without changing thread size. The Dark Clear Skies M52 × 0.75 Extension Tube provides a fixed 20 mm back-focus contribution between compatible threaded components.
A practical link in your imaging train
When your camera and accessories leave a 20 mm gap in the required spacing, this extension provides a straightforward way to make up that distance. It is intended for matching M52 × 0.75 threaded connections, with external and internal threaded ends and Dark Clear Skies branding.
Use it as part of a compatible camera-adapter or accessory arrangement where that extra distance is needed. This is a mechanical extension tube, not a focal reducer, Barlow lens or thread-size converter.
CHECK YOUR CONNECTION
M52 is the diameter. 0.75 is the pitch.
Both measurements matter. M52 × 0.75 specifies a nominal 52 mm thread diameter with a 0.75 mm pitch. Match an external thread to a corresponding internal thread, and check that the parts can seat fully without interference.
Not interchangeable with M48, M54 or M68. This tube retains the M52 connection; a different diameter or pitch requires the appropriate separate adapter.
Account for the full distance to your sensor
Start with the spacing required by your telescope, reducer or field flattener. Subtract the distance already occupied by the camera’s sensor recess and the rest of your assembled accessories. Include any filter-related spacing adjustment specified for your system.
WORKED EXAMPLE · ILLUSTRATIVE ONLY
55 mm − 35 mm = 20 mm
A setup requiring 55 mm, with 35 mm already accounted for, needs another 20 mm. This tube provides that specified extension when the connections match. 55 mm is an example, not a universal requirement.
Use the manufacturer’s reference surface and the distance to the sensor, not simply the outside of the camera body. The stated 20 mm is the spacing contribution; do not add the overlapping engaged threads again.
Specifications at a glance
| Brand | Dark Clear Skies |
|---|---|
| Product type | Fixed-length threaded extension tube |
| Thread specification | M52 × 0.75 mm |
| Specified back-focus length | 20 mm |
| Connections | External and internal threaded ends |
| Finish | Black, with Dark Clear Skies branding |
| SKU | DCS-M52-EXT-20 |
Fit gently. Check the complete assembly.
Confirm the thread diameter, pitch and mating ends before fitting. Keep the components square and start each connection by hand. Stop if the threads bind; do not force a mismatched connection.
Once assembled, check that each joint seats correctly, confirm the spacing and refocus the telescope. Adding an extension does not guarantee that every camera or optical system will reach focus.
What’s included
1 × Dark Clear Skies M52 × 0.75 threaded extension tube, with a specified 20 mm extension. Cameras and other imaging accessories are not included.
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