This picture of a great horned owl was made at the Reifel Bird Sanctuary several years ago. We have returned to this spot many times since and have not been able to make another clear photograph. If we even were able to find the bird, invariably there would be a branch or leaves in the way.
This photograph was made with a 500mm Nikon mirror lens. It has a fixed aperture of f8. Mirror lenses have a bad reputation for being soft, lacking contrast, and having noticeable light fall-off to the edges. But this picture (and several others we have made with this lens) proves that they can produce quality images.
A tripod is needed for such a long lens even if it is very light and easy to hold. In this case, the tripod was doubly necessary because these birds prefer to stay in the shadows. The exposure was around 1/15s, and if you look carefully you can see the owl's "ear" tufts are a little blurred by movement caused by a slight breeze.
Unlike most of our photographs, this was scanned onto Photo CD. This is an inexpensive way to get good quality images into a computer. However we now prefer to use a high end film scanner, partly because it is less expensive when you have the volume of photographs, but mostly because of the control you have at scan time to better the quality of the resulting image.
Finally, in case you're wondering why the format is too square to be a full-frame 35mm picture, there were some very blurry out of focus leaves on the right side that were brightly lit and too distracting. The picture was cropped in the computer.