dstick Wrote:The second and third are much more difficult..choices..
1. canon 17- 40 f/4 with the 50mm 1.4
2. tamron 28 - 75 f/ 2.8 with canon 20- 3
3 . sigma 18 - 50 f/ 2.8 with 50mm 1.8 or 1.4
DSTICK: Welcome to ST!
You have obviously already done some homework, as you've got some great lens choices.
I have previously owned the 17-40 f/4L, the 50mm f/1.8, and the Tamron 28-75 f/2.8.
I seriously considered the Canon 20mm f/2.8. It's very good, but I like the flexibility of a zoom.
I currently own the 70-200 f4L, the 50mm f1.4, and the Sigma 18-50 f/2.8.
In my opinion, my present selection is the best combination with one caveat: the Sigma will only work on DSLRs with an APS-C sized sensor. If you plan to upgrade to a full-frame camera, this is not the lens for you. If, like me, you actually think the 1.6x crop factor is an advantage, then the Sigma is excellent.
Regarding the 50mm f/1.4 vs. f/1.8: Well the 1.4 with a hood is 4x the price, but is it worth it? In my opinion, yes, for the reasons sited
HERE. Autofocus is notably faster and more accurate in low light, the main reason I disliked the 1.8. Also just try to manually focus the 1.8 with that cheesy little ring on the front. Still, the 1.8 is a GREAT bargain lens, and if your budget is limited you can't do much better.
The Tamron is "very good" in my opinion. It is probably overhyped in some web reviews. I sold mine to someone who previously owned the Canon 28-70 f/2.8L, and he commented that it's not quite as good as the Canon wide open. But it's still excellent for the price. A good "all-around" lens. I have not yet missed the 50-70mm range that I don't have covered with my current lineup.
Now the real dogfight: Canon 17-40 vs. Sigma 18-50. The 17-40 I had was not impressive at all. Terrible AF performance in low light. Not any sharper at f/4 than the Sigma. You can read my comments about it
IN THIS THREAD. For my purposes, the Sigma is much better, especially because it has excellent low-light AF performance. If you need an good
outdoor wide lens, and you plan to eventually upgrade your camera body to one with a full frame (or even 1.3x) sensor, then the Canon may be a better choice.
Then again, a series of primes like the Tokina 17mm ATX Pro, Canon 20mm and 35mm f/2 would be even better ...
All just my opinion, of course.