Complete the "Revealing the Unseen" quest, which is the fifth quest in the College of Winterhold quest line.
*possible spoilers* i will try to keep them to a minimum.
This dungeon contains Falmers, Chaurus' and Dwarven Automatons. Which are fairly strong so take plenty of potions with you.
Make your way through the dungeon, it may take a while(did me). Once you get to the Oculory place the focus crystal in it.
To focus the Oculory you need to equip your flames and frostbite spells. (If you dont have them you can find the 2 tomes up the little set of stairs behind the Oculory, rather handy aye?) Now Shoot the spells at the focusing lense, this should make the beams of light hit the middle of moving panels with the circular mirrors on. The frostbite spell moves the beams down, the fire spell moves them up. If you haven't been messing around with shooting spells at it, you only need to hit it with the frostbite spell 3 time and they will be in the correct place. Now move back up the stairs and push the buttons until the mirrors move into the beams of light. Do this so all 3 beams of light bounce off to the ceiling.
Talk to Paratus, then head back to the college. The rest of the quest is straight forward from there.
If your having trouble with the Dwarven Spheres i found it helped to shoot them with sparks and when they get close jump past them before they hit you, turn round and shoot them again. Repeat till they die.
The Chaurus' have a mean poison attack, so be sure to keep an eye on your health, and if you can improve your resistance to poison then do it, when facing them.
All the Dwarven Automatons appear to be resistant to frost.
Sorry about the video quality, was taken on my phone but you get the gist of it. Hope this helps you all :D