Comparisons at f/8.0
Full-frame image.  See below for close-up comparisons...
Sections above are enlarged below: red (28mm), pink (50mm), cyan (70mm), green (105mm) and yellow (135mm)

28mm, f/8.0, 1/250, 8.6 meters, tripod, MLU
Frame
Lens
Focal Length
16
EF 28-105/3.5-4.5 USM
28
21
EF 28-135/3.5-5.6 IS USM
28
26
EF 28-70/2.8L USM
28
28mm, f/8.0, 1/250, 8.6 meters, tripod, MLU

50mm, f/8.0, 1/250, 8.6 meters, tripod, MLU
Frame
Lens
Focal Length
17
EF 28-105/3.5-4.5 USM
50
22
EF 28-135/3.5-5.6 IS USM
50
27
EF 28-70/2.8L USM
50
Note: frame 22 may have suffered from bad focus???????
50mm, f/8.0, 1/250, 8.6 meters, tripod, MLU

70mm, f/8.0, 1/250, 8.6 meters, tripod, MLU
Frame
Lens
Focal Length
18
EF 28-105/3.5-4.5 USM
70
23
EF 28-135/3.5-5.6 IS USM
70
28
EF 28-70/2.8L USM
70
70mm, f/8.0, 1/250, 8.6 meters, tripod, MLU

105mm, f/8.0, 1/250, 8.6 meters, tripod, MLU
Frame
Lens
Focal Length
19
EF 28-105/3.5-4.5 USM
105
24
EF 28-135/3.5-5.6 IS USM
105
29
EF 70-200/2.8L USM
105
105mm, f/8.0, 1/250, 8.6 meters, tripod, MLU

135mm, f/8.0, 1/250, 8.6 meters, tripod, MLU
Frame
Lens
Focal Length
20
EF 70-210/3.5-4.5 USM
135
25
EF 28-135/3.5-5.6 IS USM
135
30
EF 70-200/2.8L USM
135
135mm, f/8.0, 1/250, 8.6 meters, tripod, MLU