Hello,
3 months back or so, I was reading an article about the Tamron 28-75mm XR Di in a french canadian magazine downthere (that was before I decided to get the lense) and the reviewer pointed out the fact that the lense give it's very best arround f/10.
2 weeks ago, this came back to my mind and I have tried the following close up of a daisy. The picture by itself as little value (flat artificial lightning) but I was frankly surprised with what I have gotten. Keep in mind that this come straight from the camera. No sharpening was applied in the camera or later on in post processing.
52mm 1/80 sec f/9 iso 250
Seb