is my lens faulty ?

hi iv got a 38-135is lens that i think could be faulty. when i take a group of people say about six in the group the mid point of the image is sharp but the image at the ends looks to me to be way to soft or out of focus even using a f stop of f8 wich i thought would be enough to give me more than enough dof. please look at the link to the images on my site the wide shot shows the hole image and the other two show the out side edge of the image. i know iv been going on about groups but did not have a group of people handy so did the best i could to show you what i m going on about.


http://www.chrisjonesi​mages.com/gallery_3277​1.html

thanks chris

at what setting 38mm, 135mm?? , Both ends of the group? in the top and bottom at all?

the trouble is on the wide setting the images on the web site were taken at the 35 mil range and at f8 hope this helps

It would help if you uploaded the shot with full exif.