AstroZap Focusing Cap for ETX 90
This focus cap from Astrozap does two jobs for your telescope. When you want help focusing the image during CCD or DSLR photography sessions, just turn the center knob to the "Open" position to reveal a trio of off-axis masks that will get the job done. This position allows the focusing cap to operate the same as a simple Bahtinov mask. However, the Astrozap Focus Cap doesn't stop working there. Rotate the wheel again to place the cap in the "Closed" position and either take dark frames or use it as you would any dust cap.
Made from lightweight aluminum and powder-coated black, this Astrozap Focusing Cap is both strong and aesthetically pleasing. It will be a helpful accessory for years to come. Three thumbscrews hold the Focusing Cap firmly in place.
The AstroZap Focusing Cap for ETX 90 will fit 90mm-100mm optical tubes.