I have question regarding the aperture setting when taking some landscape shots with an ultra wide angle lens, the Sigma 8-16mm in my case.
I have seen many people on Flickr shooting with a small aperture, at f/11 or f/16. I wonder if it really makes sense with this lens? Actually, this lens have a huge depth of field, so I don't see improvement in sharpness in that respect. Can my picture get sharper when shooting at f/16? Of course, not good idea to shoot wide open, so I thought of shooting at 1 or 2 stops lower than the wide open, especially when hand-holding the camera.
Regardless of f/#, I feel disappointed with the dynamic range this lens can achieve, when comparing even to some Nikon kit-lens. For example, when shooting a subject like tree leaves with a very bright background, e.g. the sky, I can't capture both background and foreground with reasonable exposure. Worse yet, at the interface between the tree leaves and the bright background I typically see a lot of chromatic aberration or other artifacts, so it is not always possible to lower the background exposure in software. Please have a look at the image below. Are these issues related to the ultra wide angle lens? Are there single-exposure techniques to address this issue?