Hi Andrew.
To the best of my knowledge NO they carnt be adjusted, (think they are glue fixed in), if i remember gary cooper once answered this. My mamba-lite is usable with the n/v add on to around 8 yds, for close range ratting with the n/v add on i use the jsr 3-9x40 ao (not sold new now) this will focus down to 2 1/2 yds with the n/v, but it front focus, as are just about all close focus scopes.
Dave (warbucks)
Theoben Rapid MK1 177
AA S410 22
Bushnall Scout Range Finder
Hawk 3 x 9 x 40 m.a.p scopes
Deben mini pro lamping system