These are the posibilities:
 
 

Focal Ratio	Wide Field	High Resolution	Very High Resolution
3.5m- f/10	0.3 "/pixel	0.2 "/pixel	0.1 "/pixel
3.5m -f/25  ( with ALFA)	0.12 "/pixel	0.08"/pixel	0.04 "/pixel

Actually  the optic wheel is fixed  to avoid flexures in the instrument . It's possible to use all the optics, but you have to choose one and then the staff will fix that one. At the moment the option to move it by software is disable.