I took a few this morning from the bay area in California with crystal clear skies. My longest lens is 200 mm, which, while very sharp, just doesn’t result in a big enough image in the picture. I’m guessing that your shot taken with the 300mm lens was with a non full-frame camera. With a typical 1.4 cropped sensor, that would give you the equivalent of about 420 mm in a full-frame camera like mine.

Just goes to show that you can never be big enough.