On page 256 of the rulebook it mentions that security mages can use the Magesight fiberoptic system. Obviously, there are no mentions of whether or not mages can use Magesight to target spells, so I'm wondering if it's possible or not.

IIRC, mages can target through magesight goggles, endoscopes, etc - basically, anything that does not electronically alter/transmit the image.

So I suppose you could argue that a fiber optic system would allow the same kind of thing

That section refers you to page 326, but that page number is wrong. On page 324 it talks about optical devices, and states that spellcasting targeted through optics suffer a -3 dice pool modifier. So the mages can use the Magesight system to target spells (which is the whole point of it), but suffer a penalty. Even with the penalty, it is a substantial advantage to be able to attack from relative safety.

Glyph you are my new personal hero, dude... I've been wanting to have a downside to magesight goggles in my game for some time now. Excellant find!

Yeah, now all I have to do is figure out the addition cost and Essense loss from impanting a cybereye into a Mage's palm.

ANY non-electronic sight enhancement can be used as a spotting device for magic-users?

So, theoretically, nothing hampers a mage (aside from that -3 penalty) from using say, binoculars or, if you're old fashioned, a telescope?

Color me surprised!

on top of that, nothing prevents a mage from using a mirror, periscope, one-way bulletproof glass shield, etc to cast spells either =P

There used to be rules that prevented casting via mirror, I don't see them in SR4, I may have missed them.

And, yes, you can use binoculars, periscopes, or any other form of non-electronic imaging (excluding cyber eyes, which are paid for with Essence). In 2nd Edition, there was this great piece of artwork (Laubenstein?) in the magic section of a mage happily about to blast someone while holding binoculars up to his eyes. I miss that picture.

i cannot remember any rules that forbid using a mirror for spellcasting. the only problem (with combat spells) where elemental manipulations (or for SR4: indirect combat spells). thos nasty beast have the habit of traveling the direct way towards the target. if you where using a mirror to cast around an edge, the wall would be in the direct line of the fireball, e.g.

when using stuff like stunbolt, that apwll would still go the direct way (through the wall), but as the wall isn't a problem an the astral plane, the spell would hit.

that's how i remember the stuff about mirrors etc.

Old corporate security handbook (2nd ed) had rules for using fiber optic system laced throughout building to cast through. Penalties based on range....-1 per 200 meters? ( my numbers are pure guess dont have books with me at moment.