PrimaLuceLab 9mm T2 Extension

It is primarily used to add a precise 9mm of distance within an astrophotography imaging train. This is crucial for achieving the correct backfocus distance specified by a focal reducer, field flattener, or coma corrector to ensure sharp stars across the entire field of view.

Yes. These extensions are designed to be screwed together to create longer spacing. For example, two 9mm extensions can be combined to create an 18mm extension. For finer adjustments, you can also add PrimaLuceLab's 0.5mm and 1mm T2 spacers.

To achieve a custom spacing like 10.5mm, you would combine this 9mm T2 Extension with other available spacers. The combination would be:

• One 9mm T2 Extension
• One 1mm T2 Spacer
• One 0.5mm T2 Spacer

This modularity allows you to build virtually any backfocus distance you need in 0.5mm steps.

The 105mm backfocus for the EdgeHD 8" reducer is a common requirement. The PrimaLuceLab 9mm T2 Extension is one of the building blocks you would use to reach that total distance. You would measure the existing distance provided by your camera, off-axis guider, and filter wheel, and then use a combination of extensions, including this 9mm piece, to make up the remaining difference to hit exactly 105mm.

The extension uses the standard T2 thread, which is also known as M42x0.75. It features male T2 threads on one side and female T2 threads on the other, allowing it to be inserted between any two T2-threaded components like a camera nosepiece and a corrector.

The knurled (grooved) texture on the outside of the extension provides a secure gripping surface. This makes it much easier to screw and unscrew the extension by hand, especially in cold or dark conditions where getting a firm grip on a smooth metal surface can be difficult.