Well, I got my new Canon 300 L IS f4 lens and today I tried it out at the Wakodahachie Nature Preserve. Lots of birds and other wildlife there – go in the early morning or late afternoon (good light and no tourists!)
This lens is fantastic. Great image quality, color and contrast. Fast and sharp. Works especially well with my new Canon 1.4 extender to produce images as 420 mm (equivalent of 620 mm for a 35 mm camera).
Here is one example taken today and processed in Apple Aperture 3 and Adobe Photoshop CS4.