Sigma Macro 50mm f/2.8 EX DG Lens Canon $274.95

Canon Zoom Telephoto EF 70-200mm f/4.0L USM $580.00

Hi,

I'm not going to make overly specific lens recommendations.

Each of us is so different in our needs and lens choices, which are actually much more important determining how our photos will end up looking than the camera model we buy.

I'd suggest you consider several things...

First, use the lens you already have a lot. Experiment with it, find out how it limits your shooting and then you will have a much better idea what to buy next, or if one is even needed.

Second, don't scrimp on lenses. You will very likely be using them on future cameras, long after the camera you just bought has been replaced by another "latest and greatest" model. My lens kit has gradually grown over the years, but I am still using many that have been on at least seven different camera bodies so far (in seven years). I'm only now considering replacing one lens, out of the thirteen total that I presently use in my Canon system. There's another I use so much I wouldn't mind having a backup for it.

Now, if you wish, talk with the instructor in advance of taking the course you have planned. They may have some specific advice for you, or prefer that you use a certain type of lens for the class.

Also, you might want to get a current copy of Canon's "Lens Work", which discusses all the different lenses available and some ways they are used. I downloaded a set of PDFs of this book that one of the Canon websites (Europe?). It can also sometimes be found in a hard copy. The Canon lens system is the most extensive one currently available, so this book can be a very valuable resource. The current version might lack some of the very latest lenses, like the 55-250, 200/2 and 800/5.6.

There are also some great books around about choosing and using lenses in general, not specific to Canon but the same basic principles apply to all.

Other good reading, the Magic Lantern Guide Book series (for your specific camera model) and similar have at least a full chapter devoted to choosing and using various lenses.

You are probably aware, there are several third party manufacturers also offering lenses to fit Canon. Tokina, Sigma and Tamron are the main ones. Some of their offerings do a good job filling in particular gaps in the Canon system or are simply excellent alternatives. However, be a little cautious. Canon pretty much guarantees their lenses will fit and work on their cameras now and in the future. There are no similar guarantees with third party lenses. This has become a lot more important issue today with auto focus and electronic lens-to-camera communication and computerized controls. There have been some incompatibilities, for example, between some older Sigma lenses and newer Canon bodies. To their credit, at the time Sigma would re-chip and upgrade the lens to correct the problems, at no cost.

It would probably be best to supplement what you have now with other lenses, rather than duplicate too much. For example, since you have an 18-55, you may want a wider angle lens like the Canon 10-22 or a more telephoto lens like the 70-200, depending upon what appeals to you. But, whatever you do now probably won't be the last lens you ever buy. So, think of it as building a system a little at a time, rather than jumping into the whole thing all at once. Eventually you might want to upgrade the kit lens to something better, just be sure to give it a good workout and find your limits with it, before deciding.

Besides focal lengths, there are other important factors to consider. For example, if portraiture were an important thing to you, a larger aperture lens that allows nice background blurs might be a good choice, such as the Canon 50/1.8 or 50/1.4.

Or, if you need to shoot small subjects up close and personal, then you might want to look at Canon's EF-S 60/2.8 Macro or EF 100/2.8 USM Macro lenses that can focus close enough to go to 1:1 (full life size) magnification all on their own, without any accessories.

There's also the option of renting before you buy. This is particularly helpful to try out more expensive lenses, to see if they truly meet your needs, before committing to a purchase.

Another way to "check out" lenses before you buy is to join a local photo club. Some are likely to be Canon users who have key lenses that you might be considering, and willing to let you try them out. I'm a member of a Photo Meetup group locally that now has nearly 700 members. One member was considering a 70-200 lens, but unsure whether she wanted the f4 or the f2.8 version. I lent her my 70-200/2.8 to try just briefly and she quickly was able to decide it was larger and heavier than she was willing to carry around, so opted for the f4 version instead. She also decided to buy the IS version, when she saw how helpful that was getting sharp, hand held shots with a telephoto zoom.
(check photo.meetup.com for groups in your area, if you wish)