M48 M48 Variable Extension 17mm - 22mm
This is a variable M48 adapter/extension with a M48 male thread at one end and M48 female thread at the other end.
It is built from a 5mm and 8.5mm extensions, plus a 2mm wide securing ring with M48 male thread; the 5mm part has got a long male thread (10mm), but other than that the parts could be also used as separate M48 extensions.
It will give you the necessary increased aperture when imaging with a full frame camera.
Optical length can be varied between appr. 16.5mm - 22mm
At 22mm length the two parts are being held by only few turns, so it's recommended to use it at max appr 21mm optical length.
Compatible with the following Skywatcher adapters 20238 Nikon M48 Camera Adapter and 20237 Canon M48 Camera Adapter