Hello All ,
i need to buy a lens and i dont know which one.
im looking for something in the range between 16 and 50 it can be a bit less or a bit more doesnt matter.
Lenses i have are:
11-16 2.8 Tokina
50mm 1.4 Sigma
100mm macro USM IS L 2.8
100-400mm Canon L
(future upgrade to full frame)
i dont mind third parties as long as they are proven to be better than the canon one. as well i dont like lenses that change the aperture unless is really necessary like in the 100-400 because it will be impossible constructing this lens at that price with constant low aperture.
You didn't say what your budget is, what you're shooting primarily, how important IQ is to you, if you need Image Stabilization, primes or a zoom, but the EF-S 17-55 f/2.8 IS is generally the best option for an APS-C body like the 7D. It is a little pricy but it's worth it, especially if you can find a nice used one. That's what I did and it has proven to be an excellent lens and a great value. I can sell it for what I paid for it, $700, at anytime.
The EF-S 15-85 F/3.5-5.6 is the next obvious choice. Compared to the 17-55 you're gaining 30mm of zoom on the long end, but will have a variable aperture to deal with, which was a deal breaker for me. I, also, much prefer a fast, constant aperature.
The EF 24-70 f/2.8 L and the EF 24-105 F/4 L IS are two great choices, also, especially if the upgrade to a full-frame is imminent. The problem is, on an APS-C body you may miss the 17-24 range that you're losing versus the EF-S lenses, considering that you have the Tokina 11-16, which is a great lens, but has a very narrow zoom range. However, you could sell or trade off the Tokina for the EF-S 10-22 f/3.5-4.5, or maybe the Tamron 10-24. Then the 24-70 or 24-105 won't leave a gap. Then again, zooming with your feet may suffice.
The EF 16-35 f/2.8 L and the EF 17-40 f/4 L are excellent lens, too, but for me they are just bit too short in their range and neither has IS, which is something I need for standard and telephoto zooms
The Tamron 17-50 non-IS is also a good choice for the APS-C bodies and is a bit more affordable than the EF-S 17-55.
The EF-S 18-55 isn't a bad lens by any means either. It's not quite in the same category as the others, but it is very usable.
Keep in mind that all of the Canon lenses mentioned, with the possible exception of the 18-55, all hold their value extremely well. If you can locate nice used copies from someone you trust you can break even, if you buy right.
Gather other opinions here, then compare your choices at www.the-digital-picture.com