Photoclubalpha

The subject is the sharpness of CZ 24-70mm f/2.8 lens.
My concern is the sharpness on the edges of the picture at focal length 70mm.

My first case is a lens I purchased. I tried it out at 70mm F/2.8 on Sony’s A700.
The lens was not sharp at all on the edges. I returned the lens.

My second case is this picture:
http://a.img-dpreview.com/gallery/sony_ ... 990_dw.jpg
Sony Alpha 900 Preview Sample, 70 mm, ISO 200, 1/640 sec, F8.0, +0.0 EV, Sony 24-70mm f2.8 ZA

The blue and white handrails on the external sides of the towers are not sharp.
The picture must be reduced to a 5”x7” size to get a rather consistent image.
The picture was shot at a rather ideal F8.0 opening!

Can these poor performances of two random lens samples be explained by “bad luck”?

The samples like pretty normal to me for a JPEG. Some residual CA, plus the JPEG effects, can produce this sort of result. I would test using raw and correcting CA in a good converter like DxO, C1 Pro or ACR/Lightroom. I find that all lenses - even the best like Nikon's 24-70mm f2.8 - need some correction for perfect results.

David