Will this 4" Extender help me reach focus with a filter wheel on my William Optics FLT 132?
Yes, this is its primary purpose. The 67 mm of extension is designed to push the focal point outward, providing the necessary back focus to accommodate accessories like filter wheels and off-axis guiders that would otherwise prevent you from reaching focus.
What are the thread specifications for the William Optics 4" Extender?
The extender uses M92 threads. It features an M92 male thread on the light-in (telescope) side and an M92 female thread on the light-out (camera) side for a direct, secure connection.
Is the William Optics 4" Extender compatible with telescopes other than the FLT 110 and FLT 132?
While it is specifically engineered for the William Optics FLT 110 and FLT 132, it may work with other telescopes that feature a 4" focuser with a female M92 thread. You must verify your telescope's specific thread size and back focus requirements before purchasing.
Why is it called a "4" Extender" if it only provides 67 mm of extension?
The "4"" designation refers to the size of the focuser it is designed to mate with, such as the 4" focusers found on the FLT 110 and FLT 132 telescopes. The actual optical length it adds to the light path is 67 mm.
I am trying to do prime focus imaging with a DSLR on my FLT 110 and can't reach focus. Is this extender the solution?
It depends on which way you need to move the focuser. If you cannot reach focus because the focuser is racked all the way out, this 67 mm extender will provide the additional length needed to achieve a sharp image. If your focuser is racked all the way in, you need less back focus, and this extender will not help.
Does the William Optics 4" Extender have any optical elements?
No, this is a purely mechanical extender. It is a hollow tube designed only to increase the distance between the focuser and the camera. It contains no lenses and does not alter the focal length or focal ratio of your telescope.
