Decision between Canon EF 17-40 mm / F4L and Canon EF 35 mm / F2 USM

gukejing wrote:

I own now following gear:

• Canon 500D body
• Canon EF-S 18-55 mm / f3.5-5.6
• Canon EF 50 mm / f1.8

the kit lens is rather useful to walk around and I start to practice to use some focal length like 35, 50, 85 after multiplying the crop factor to simulate the viewing angle and depth of field on full frame (not sure whether the method is correct).
I found the way works fine for me as some focal lengths are close to human view angle.

But the image quality of kit lens is not as good as a fixed focal length I have, the cheap 50 mm. Therefore I would like to improve my pictures quality by upgrading my gears by following either of two approaches:

• Use the luxury lens
• Use prime fixed focal length lens

Due to limited budget, I found two lens:

• 17-40 mm / f4L to cover the range of 18-55 mm
• 35 mm / f2 to cover 50 mm by considering the crop factor

Price would be slightly different, can anyone who ever tried two lens on APS-C body tell me the feeling or some picture examples to let me have some ideas which one to choose.

Your comment is welcomed to help me understand the pros / cons of the products.

Of course, the 3rd party lens are also welcomed as long as the price is not more than $800.

Thanks a lot.

Kejing

...for a crop DSLR, given the better options that are out there for the money (e.g. Sigma 17-50 / 2.8 OS, Canon 15-85 / 3.5-5.6 IS, etc.).

The 35 / 2 IS is excellent, however, but, were it me, I'd definitely pony up a bit more money and get the Sigma 18-35 / 1.8, unless IS was really important.