Starizona Threaded Focuser Adapter

A threaded adapter creates a rigid, secure connection that prevents tilt and sag. A 2" nosepiece held by a thumbscrew or compression ring can easily shift as the telescope slews, throwing off collimation and resulting in elongated stars. For imaging, a fully threaded connection like the Starizona adapter is always the superior choice for maintaining perfect optical alignment.

The choice depends on your camera's sensor size and your other accessories.

• M42 (T-thread): Best for cameras with smaller sensors (like the ASI533MC) or if your existing spacers and filter wheels are all M42.
• M48 (2" Filter Thread): Recommended for cameras with APS-C or full-frame sensors (like the ASI2600MC or ASI6200MM) to prevent vignetting, which is the darkening of the corners of your image.

You need to know the specific thread size and gender (male or female) on your focuser's drawtube. This is often listed in your telescope's manual or on the manufacturer's website. For example, many Takahashi focusers use an M72 female thread, while some Explore Scientific focusers use an M68 female thread. Carefully measure or verify your focuser's thread before ordering.

Yes, all adapters consume some amount of backfocus. The exact amount is different for the M42 and M48 versions of the adapter. Starizona includes spacers with each adapter to give you more flexibility in achieving the precise spacing required by your flattener or reducer.

For that setup, you would select the Starizona adapter with "M72 x 1mm Female (Takahashi)" threads on the focuser side. Because you are using a full-frame camera, you should choose the M48 version for the camera side to minimize vignetting and ensure your sensor is fully illuminated.

The 2.5" Hex focuser typically has M68 x 0.75mm female threads. By selecting the corresponding Starizona adapter, you can thread your entire imaging train—reducer, filter wheel, and camera—directly onto the focuser drawtube. This creates a single solid unit, preventing any part of your camera setup from flexing or tilting as the telescope moves across the sky.