[graham.hobart (Graham stevens)]

my FS 106 came with the extender which increases focal length and reduces the fov. This doesn't matter to me that much as I have on it currently a APS sensor so 44mm image circle would be fine.
My question- it seems to be a lens unit with 2 other removable? extension tubes on the back, do I use both of these or are they for adjusting focus position?
Graz