This test is designed to show how much advantage is gained by using a prime, versus using a modern zoom, for telephoto shooting. The AF version 300mm F/4 is a highly regard classic prime; the 70-300mm F/4-5.6 VR considered an outstanding enthusiast lens. Both are reasonably affordable ($400-450 used) with the trade-off being convenience and lens stabilzation, versus some of Nikon's better glass and lower f-stop.

So how big is the difference? You can decide for yourself. I see very little in the center of the image, but detectable softness around the edges of the zoom. Of course, at wider apertures the diffences become more apparent...the 300mm F4 stays sharp down to at least F/4.5. The 70-300mm VR looses steam below F/8 and is discernably soft at F/5.6 at 300mm. At any but really large print sizes, however, I am satisfied with both. I value the 300mm F4 more for its isolation and high shutter speed for shooting sports than I do for it's superior glass quality. The 70-300mm is that good.

The tests were done using a D300 set on a tripod, using mirror-up 30sec delay. The lenses were focused manually, with a resetting after every shot. Each lens setup was shot three times, and the sharpest of the three chosen for comparison to the other test configurations. So twelve shots went into the four final choices shown here. Each of these was cropped to approximate the view seen at 600mm (using a 2x adaptor). So the 300mm setting using no telextender was cropped significantly while the 420mm shots using the Kenko Pro 300 1.4X were cropped less severely. While some may criticize this approach, I fell it reflects accurately the real-world use that would be made of these lenses in this configuration for shooting distant scenes or sports action.

Small size (800 pixel long side) versions are on page one. They basically look identical and pretty much show what small print sizes will look like.

Large (3000 pixel long side) versions are on page two. These photos were sized to the pixel density of an 8x12 photo at 250ppi. These are where you will begin to see differences. In the center of the picture, I used brick and roof shingle and masonary detail for judging; near the edges I used both building detail and leaf detail. Have fun judging for yourself.