Maximum Apertures
Full-frame image.  See below for close-up comparisons...
Section in blue has been enlarged in the comparisons below

Focal length: 28 mm, 1.8 meters, tripod, MLU, no IS
Frame
Lens
Aperture
Speed
2
EF 28-105/3.5-4.5 USM
3.5
1600
3
EF 28-135/3.5-5.6 IS USM
3.5
1600
1 EF 28-70/2.8L USM 2.8 2000
Focal length: 28 mm, 1.8 meters, tripod, MLU, no IS

Focal length: 50 mm, 3.2 meters, tripod, MLU, no IS
Frame
Lens
Aperture
Speed
5
EF 28-105/3.5-4.5 USM
4.0
1000
6
EF 28-135/3.5-5.6 IS USM
4.5
800
4 EF 28-70/2.8L USM 2.8 2000
Focal length: 50 mm, 3.2 meters, tripod, MLU, no IS

Focal length: 70 mm, 4.5 meters, tripod, MLU, no IS
Frame
Lens
Aperture
Speed
8
EF 28-105/3.5-4.5 USM
4.5
800
9
EF 28-135/3.5-5.6 IS USM
5.0
640
7 EF 28-70/2.8L USM 2.8 2000
Focal length: 70 mm, 4.5 meters, tripod, MLU, no IS

Focal length: 105 mm, 6.7 meters, tripod, MLU, no IS
Frame
Lens
Aperture
Speed
11
EF 28-105/3.5-4.5 USM
4.5
800
12
EF 28-135/3.5-5.6 IS USM
5.6
500
10 EF 70-200/2.8L USM 2.8 2000
Focal length: 105 mm, 6.7 meters, tripod, MLU, no IS

Focal length: 135 mm, 8.6 meters, tripod, MLU, no IS
Frame
Lens
Aperture
Speed
14
EF 70-210/3.5-4.5 USM
4.0
1000
15
EF 28-135/3.5-5.6 IS USM
5.6
500
13 EF 70-200/2.8L USM 2.8 2000
Focal length: 135 mm, 8.6 meters, tripod, MLU, no IS