Let's say you PeIm a wall so it becomes invisible. This will reveal whatever is on the other side on the wall. Will this make them within sight range?
I'm inclined to say "yes," because the description for Sight range says "Anything that the magus can see." If this involved Rego, to move the visual species, I would have more of a problem, but simply turning the intervening wall invisible should work.
It's not entirely clear from the RAW, but in this specific case, I guess yes, it will bring into Sight range things obstructed by the wall that you'd be able to see if the wall were not there.
If the example involved seeing stuff at Arcane Connection range through some Intellego Imaginem spell, the answer would be far less clear. I would not allow those things to be treated at targeted at Sight range, though I guess a number of troupes would.
EDIT: Basically, the same answer as Peregrine_Bjornaer's above.
That is what I thought as well.
On a related subject, this spell might prove useful:
Wizard's wandering window
MuIm 20 (1, Sight +3, Sun +2, Part +1, Moving image +1)
You make any one object appear transparent like if it was made of colored glass. You may move the spell anywhere you focus your eyes. For large objects, the area made transparent should not be bigger than a 1 pace circle, and not more than a half pace thick.
Shouldn't it have a requisite for the material?
There's a pure MuTe10 in HoH:TL p141 that does the same thing.
No. You're effectively casting the spell again and again, on a new target every time you move your eyes.
Not possible.
You're also changing an image into something you cannot see (which is the whole point, neh?)
You could make a InFo spell to "make your sight unaffected by (Form)", but that's a very different approach.