I recommend that you get a sigma 150-500 os. And wow, what a coincidence, I just happen to have one for sale! I started with a rebel xti, then a 50d, but I pretty much knew I was going to move up to a full-frame when funds allowed, so I refrained from buying any ef-s lenses since they cant be used on full-frame camera. I did follow the advice to buy better lenses before getting a better camera (after i got my 50d), and have not regretted it. I eventually got a 5dII, and though I would like to have the 5dIII(the 1dx is beyond my budget), I am still buying lenses I want first. I am not a Pro, so having a better camera than the 5dII is not as critical to me(And lack of funds). The 135/f2 is an excellent prime lens and is not as costly as some of the other L primes, if you want that focal length (216mm on crop camera). The newer Rebels are really good though, so if you decide to stay with a crop camera that would be a good move up if you are on a limited budget. I just modified my post: I recommended the wonderful 100 macro, but forgot that you already had it. A great prime/macro lens. I have had the zoom ranges covered for awhile, and am becoming more interested in primes also. The Samyang 14mm UWA is a good inexpensive MF lens if you want something that wide. I prefer it @14mm over the Canon 16-35L @ 16mm. The Sigma 35mm Art lens has been getting great reviews everywhere, and is less expensive than the Canon L. I just ordered one. There are quite a few 50mm lenses. I have the Sigma 50/1.4, and it takes decent photos when it focuses correctly. Many users have problems with the focus, so would think twice or 3 times b4 buying it. I also have the Zeiss 50 1.4 p MF lens now and perfer it over the Sigma. Though it is better stopped down to f2 or more, and some dont like the bokeh wide open. It is one the less expensive Zeiss manual focus lens. I am still considering the 50L, and might get it when it on sale @ B&H photo again. I think it has a mail-in rebate for $180 there now along with about 45 other lenses. I have the 85L II, one my favorites, but very expensive. Some like the Sigma 85 at a lower price, and the Zeiss 85.I already have the Zeiss 21, 50p and 100mp, all manual lenses, and very expensive, but I love them all. I also have the Canon 135L and highly recommend that one.