Lens Advice: 2 Mid-Level Primes or 1 L-Series Wide Angle Zoom

YardYeti wrote:

Will the image from the EF-S 15-85mm f/3.5-5.6 IS USM be that much better then my kit lens (EF-S 18-135mm f/3.5-5.6 IS)? Also, can you explain better why the EF 17-40mm f/4L USM would not be good for cropped. i thought it would give a good range for 1.6 like a 28-60. Are you saying I would want something that allows for a wider picture? You mention that it is not a crop lens, what specifies that it is not. This will be my first lens purchase, and I cant afford to choose incorectly.

Yes, the 15-85 will give you a noticeably sharper image than your kit lens. See here.

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=678&Camera=736&Sample=0&FLI=0&API=0&LensComp=675&CameraComp=736&SampleComp=0&FLIComp=0&APIComp=0

And it's also 3mm wider on the wide end, which is a more significant difference than you might think.

It's also a better choice on a crop than the 17-40L for the following reasons:  equal or better IQ; much wider zoom range, and 4-stops of IS (vs. none on the 17-40).

Will the EF-S 17-55mm f/2.8 IS USM offer that much better of a picture then my kit lens? If so, i will just need to save up some more cash and go this route. Would I want to keep my kit lense with this? I cant afford the 10-22 and 17-55 now.

Yes, the 17-55 will also give you noticeably better IQ than your kit lens.

IMO, if you're going to go with a zoom, the EF-S 15-85 and EF-17-55 are your best choices on a crop.  Go with the 17-55 if you need or want its faster aperture.  Go with the 15-85 if you want its wider zoom range.

Finally, although primes can be sharper than zooms, this isn't as true as it used to be.  Modern zooms are quite sharp.  The primary reason to go with primes, IMO, is that they tend to be faster--i.e., have wider max apertures.  So if you need a very fast lens (faster than f/2.8) for lowlight shooting, or to give you very shallow depth of field, then a prime is probably the way to go.  Bear in mind, though, that many of the more inexpensive primes aren't particularly sharp wide open and need to be stopped down some to give you a crisp image.

Good luck with your decision.