Focal Length and Compression

It's been awhile since I've been writing here.  This isn't because I haven't taken any pictures—it's because I have little time in my personal life to write much of anything, to say nothing of a photography blog.

However, I recently acquired a Nikkor 400mm f/5.6 AI-S and 85mm f/1.8 (AI'd).  Manual focus isn't everyone's thing, but I have enjoyed it a fair amount, and these are focal lengths of some interest to me, and help to illustrate how the longer focal length tends to "compress" a scene.

Here's a picture from the 85:

Fire hydrant?  85mm f/2.8, 1/5000s @ ISO 400

While they're not super obvious, there are clearly buildings in the background some distance away.  A somewhat equivalent picture from the 400:

400mm f/5.6, 1/1600s @ ISO 800

I did not take the most extreme care to ensure that the scenes were identical, but hopefully the compression is fairly obvious.  The background "feels" so much closer in this image than it does in the previous.  This is due to the compression induced by the focal length.  What this means is that the longer focal length (i.e., telephoto lens) tends to bring the background closer while the shorter focal length (i.e., wider angle) will present a scene with greater depth.


And just to make you jealous, a moon shot from the 400; it's cropped, run through unsharp, and has been color corrected some:

400mm f/8, 1/1000s @ 800 ISO; hand-held