Test my lens and solution required

[Yisehaq]

hey all,

After experiencing alot of problem on sharpness, I have decided to test my equipments. For now, I am testing my lens.

I used the following technique suggested by jlabel.

lens sharpness-how to test

The best way to check technical focus is using your camera on a tripod and focusing and shooting a ruler, chose a number and shoot it if the focus is misplaced it may be a lens problem, some newer cameras have the option to configure this kind of problem, also you will be able to see if your lens is sharp enought for you, you should also use f/5.6 or f/8 for this test.

Additional info.

I used a tripod, mirror was locked up and all shots were taken using a cable release. The focus point was [20] on all the shots.
No PP what so ever.

My lens is Sigma APO 70-300mm F4-5.6 DG MACRO
My camera is Canon 350D

what do you think?