Updated link, made a few changes:
Observation scope zoom is the same as attack periscope (1.54->1.5 and 6.1->6).
Reworked mask to incorporate the reticule which disappeared after changing zoom. Purely cosmetic though, at least it looks the part.
Added a version integrating the colour filter from OPCF; 4 versions in all:
MRP
MRP+Freecam zoom
MRP+OPCF
MRP+OPCF+Freecam zoom
Credit for the freecam tweaks go to Elanaiba.
Striving for realistic optics, much like the ones Hitman did for SH3. For the moment, other similar projects are underway and I have my own as well, so I'll leave it at this for now. If the others don't work out or something, or other projects are complete, I'll pick this back up.
Previews in post #2 updated.