This 8mm extension ring is useful for achieving the correct back focus required for astrophotography, where a few millimetres are critical.
The extension ring has an M48 x 0.75 male thread on one side and an M48 x 0.75 female thread on the other side. The optical thickness is 8mm.
|Connection (side a)
||M48 x 0.75 male
|Connection (side b)||M48 x 0.75 female|
|Optical thickness||8mm (without male thread)|
|Outer diameter||50.9 mm|