During 1-50 you get exp if you're within 5 levels (above or below). For veteran levels I believe they changed it to where it doesn't matter, though I may be wrong.
(NA) Anlaemar with 750+ Champion Points Member Since April 15, 2014
(EP)AlrikVadason - Nord Dragonknight
Tank
(EP)MatdasiHlarrobar - Breton Mageblade
Formerly known as Ra'darAhdhari - Main DPS 40k Self Buffed
(EP)MarrecVadason - Breton Templar Healer
(EP)Nameless - Altmer Sorcerer - Secondary DPS
- The only sovereign you can allow to rule you is reason -
You can be no more than 5 levels above the party leader to get XP/loot from the mobs.
If you are completing the dungeon for the first time, you will get XP for turning in any associated quests regardless of your level. You will also get the achievement for completing the dungeon regardless of level.
If you're more than 5 levels BELOW the Group leader, I would suggest either many, many soul gems and repair kits or hiding
because the dungeon will be levelled to the Group leader.
However, as long as you get a whack or two in on the boss, between deaths that is, you'll get stuff plus XP plus the achievement.
I also doff my hat to you for going in with a Group Leader that many levels above you! In fact, after you've done it, put up a post to say how it went because, I dare say, a lot of people would be interested.
Alternatively, if you're playing with a mate several levels above you, YOU be the Group leader and save on the soul gems!