What is the advantage of using this Starlight Instruments 3.5" threaded end cap over a standard compression ring adapter?
A threaded connection provides a much more secure and rigid attachment for your camera and filter wheel. Unlike compression rings that can allow for slight misalignment or sag under heavy loads, the 3.0"x24tpi thread on this end cap ensures your entire imaging train is held perfectly orthogonal to the focuser drawtube, eliminating a common source of tilt and elongated stars.
Will this end cap fit my Starlight Instruments 2.5" or 3.0" focuser?
No, this end cap is specifically designed to thread onto the drawtube of a Starlight Instruments 3.5" Feather Touch focuser. It will not fit the smaller 2.0", 2.5", or 3.0" models.
How does this 3.0"x24tpi end cap prevent tilt with my SBIG STX16803?
The SBIG STX16803 is a substantial camera. By threading it directly to this end cap, you create a single, solid assembly with the focuser drawtube. This direct-thread path distributes the load evenly and prevents the camera from sagging or tilting, which is critical for maintaining a flat field and round stars, especially in the corners of the large sensor.
Is this the correct adapter for attaching an FLI 5 Series filter wheel to my 3.5" Feather Touch focuser?
Yes, this end cap is designed to provide the correct 3.0"x24tpi male thread required to connect to FLI 5 Series (CFW 5-7) filter wheels. This ensures a direct, secure fit without the need for intermediate adapters.
Does this Starlight Instruments end cap have collimation screws?
Starlight does not say for this end cap. Its 3.5" focuser manual notes that most of its end caps have 3 set screws on the face that allow collimation (tilt) adjustment with a 1/16 hex key.
What tools are needed to install this 3.5" end cap on my Feather Touch focuser?
Most Starlight end caps are locked by 3 set screws on the face: loosen them with a 1/16 hex key, unthread the existing end cap (such as a 2" compression ring adapter) from the drawtube, and thread this end cap in its place.
