I recently purchased a canon 24-105mm F4 lens, and took the images below with this lens on my Canon T2i. This is what the Sun looked like setting in the dust...click to enlarge:
Below is a crop of the Sun at full resolution. Click it to enlarge it to full size (you may have to click it twice if your browser automatically re-sizes images) and you can see the spot group on the upper left that the students noticed.
Finally, I captured this image of one of the students looking at Jupiter through the 20-inch Jamieson Telescope. It was a 1 second exposure, ISO 400, at the 24mm setting, handheld...As you can see, I am pretty happy with this new lens. It focuses quickly and accurately and the color rendition is beautiful.