Thanks for all of your helps
Reading through some review, I see that the 17-55 is actually sharper than the 24-105. Unbelievable:bigeyes:
However, I shoot in low light but not very often and used to set F5.6(at least)+ flash to get the DOF. I think the 24-105 is more suitable for me as I can get longer range. Moreover, I also intend to upgrade to 5D next year so need a full frame lens.
But really, I still always ask my self why should I go for full frame? Using 1.6X, I can get great lenses with cheaper price like 10-22 or 17-55 (actually sharper than 17-40 and 24-105). Knowing that DOF is different in a full frame cam but how much I can really appreciate it? Moreover, a full frame cam produce more distortion and so require better lens also. Then, after much calculation I see that full frame cam is just a waste of money as I always do things according to phrase "pay for what you can really see".
What do you guys think? Should I buy a full frame later or just stick with 1.6X body and the 17-55 IS? Please correct me if I am wrong at some points.
Thank a lot
Which lens to buy hinges on your decision to go full frame or not. The merits and needs of FF have been discussed elsewhere.
If you are staying with 1.6X then there are few better lenses than the 17-55 at f2.8. In fact you should thank Canon for making this lens because two years back I had to try so many different lenses and brands of lenses and yet I hardly get this image quality. The bokeh of this lens at 2.8 can equal that of some prime lenses. So you have almost all you need in one fast lens. Only problem is price and perhaps build quality for some. The 17-55 goes from 68 to 23 degrees.
If you are going full-frame then there are several options. e.g. 24-70/2.8, 24-105/4. Photoshop cannot turn a picture taken at f4 into f2.8. But photoshop can easily crop a picture taken at 70mm into 105mm with little virtual loss in picture quality as the mpix of FF DSLRs keep rising. The 24-70 goes from 74 to 29 degrees. The 24-105 goes from 74 to 19 but with half the light as the other two lenses.