Baader M48 Extension Tube - 5mm

Its primary use is to fine-tune the back focus distance between an optical corrector (like a field flattener or coma corrector) and the camera sensor. Most correctors require a very specific distance, often 55mm, and this 5mm tube helps you achieve that exact spacing when your existing adapters leave a small gap.

Yes, this is a classic symptom of incorrect back focus. If your current spacing is slightly too short, adding this 5mm tube could be the exact correction needed to flatten the field and produce sharp, round stars from corner to corner. You should measure your current optical path to confirm if you need to add 5mm.

Yes. The M48 x 0.75 thread pitch is the standard for 2-inch astronomy filters. You can thread this extension tube directly onto a filter or into any accessory that uses M48 threads, such as a filter drawer or the nosepiece of many cameras.

Absolutely. You can stack multiple tubes to achieve custom lengths. For example, stacking two of these would give you a 10mm extension. This allows for a modular approach to building out the exact spacing your optical system requires.

While variable spacers offer flexibility, they can sometimes introduce optical tilt if not locked down perfectly square. A fixed extension tube like this Baader 5mm provides a more rigid, stable, and perfectly collimated connection, eliminating a potential source of image degradation.

No. The M48 thread standard (also known as a "wide" T-ring) is specifically designed to provide a larger clear aperture than the older T2 (M42) standard. It is intended for use with full-frame (24x36mm) sensors and will not cause additional vignetting.