focusing speed comparable at F4?

[ConnorMcLeod]

Want a lens to complement my 17-40 to shoot my daughter on 1.6x crop , indoor & outdoor . Has 430EX flash.

Below all USM. At F4, do they have the same focusing speed?

EF 24-105mm f4L IS USM
EF 28-105mm f4-5.6 USM
EF 28-135mm f3.5-5.6 IS USM

Seen review 28-135 edge is not sharp compared with 28-104 f4-5.6.
Are the 24-105 and 28-105 sharpness comparable?

[cks2k2]

Aperture opening does not affect the focusing speed. With USM it's fast.
Definitely the L lens wins when it comes to sharpness.

[Snoweagle]

Originally Posted by cks2k2 Definitely the L lens wins when it comes to sharpness.

Not exactly. There are many non-Ls that are as sharp as Ls in the same class. What makes Ls different is the contrast.

[ditikolon]

Originally Posted by Snoweagle Not exactly. There are many non-Ls that are as sharp as Ls in the same class. What makes Ls different is the contrast.

Agreed. My Tamron 17-35 gives me pictures that are every bit comparable to the 1740L in terms of sharpness, but color cast and contrast... the 1740L is just beautiful.

[Snoweagle]

Originally Posted by ditikolon Agreed. My Tamron 17-35 gives me pictures that are every bit comparable to the 1740L in terms of sharpness, but color cast and contrast... the 1740L is just beautiful.

That's why sharpness is not a critical characteristic of a L, it's the contrast and elements that makes the difference.