A decent consumer SLR body, usually $600–900, is a big investment for most people. But if you can’t also afford to buy at least one good lens with it, you’ll get better photos by going with a less expensive kit, such as a high-end point-and-shoot or an entry-level mirrorless setup.
I’ll second Marco here, with the caveat that you really can take a great photo with any lens or camera. BUT the overall quality when you try to use that photo later on is where you will really see the trade off and likely find frustration.
- Canon 50mm f/1.4
- Canon 17-40mm f/4
- Canon 80-200mm f/2.8 (This is seriously an old-school lens)
- Canon 100mm f/2
I used to have the Canon 24-70 f/2.8 (affectionately called “The Brick” because it weighs about a ton), but I never used it for anything because the focal range for the weight added was not a good trade off. It is, however, one of the sharpest, and brightest lenses I have used.
The two most used lenses in my setup for my Canon is the 50mm and the 17-40. I use the 50mm for any type of “normal” shooting and the 17-40 for a wide-angle for my day job in real estate.
Prime lenses (those with fixed focal lengths) are amazingly more sharp and less distorted than zooms. If you can, you should own at least one in the 28-50mm range (28 on a APS-C sensor, 50 on full frame — adjust to taste).
Here’s where I will differ with Marco, the 40mm he recommends is excellent, but there is also another really cheap lens, the 50mm 1.8. The build quality is poor, but the lens is sharp and pretty fast. It’s a good entry step, Amazon has it listed at $110, but you can get it cheaper: refurbished for $90, or you can find them from people who have stepped up for cheaper on Craigslist sometimes for as low as $65.
Tip: If you need to test the lens when you go to buy a used one (and you should), back focusing will be a really good test and easy to do on site.
For me the 50mm 1.4 is really all I need for personal photography and the 17-40 is all I need for work. There’s a lot of great lenses for a lot of money out there, but many are not needed. Your best bet is to get one good lens and see what you are lacking from there — also remember that buying a good lens will transfer from body to body with you. That 80-200mm lens I listed above is handed down from my Grandfather, it’s probably from the early 90s and still works fine.