The one noteworthy point was between the 20-40 and Tamron 28-75 at 28mm. Exposure data is shown as identical but the Tamron is darker by a notch; it is clear in the leaves against the tree trunk and especially in the skyline clouds. The other images look like the LimiZoom, only the Tamron has cloud detail. These all were jpeg/bright so processing was the same, and focus was obtained on the notch in the left-side tree trunk. Honestly though, these clouds were moving fast... some changes just happen with outdoor scenes. I was not planning to shoot these but the sun came out with no early notice, so I used it!
These two shots were cropped by Picasa when converted to a collage so
more of the scene is visible on my screen for all the images.