How to move big buildings

As we all know, walking is wearing out your muscles, soles and motivation. Wouldn't it be much nicer if it would just take a moment's thought to move your target closer? Look at the mile long walk to the building in the background on the picture to the left. The silvery car in the front is just a couple of steps away, but then the strenuous part beckons.

The magic unveils itself when you hire someone with big tools that can move buildings in a heartbeat. Actually, it looks like he pushed all and everything behind the silver car closer up - nice!

Of course, that's cheating! In two respects, actually:

1. I had to walk quite a bit away from the scene to take the second picture.

2. The focal length of the lens went from wide (17mm = 27.2mm/35mm equivalent) to long (should call it "narrow", 200mm = 320mm/35mm equivalent).

So, combining a short walk with an increase in focal length had this "compression" effect. As opposed to some statements about this phenomenon, it's not the focal length that is responsible for it. The picture on the left was also shot with 17mm focal length, only from the same spot where the second picture was taken: Behold, the same "compression" effect!

The reason: it was cropped out of the one on the right (hence the little blurriness and the weird white balance).

So, what's responsible for the compression effect? Angle! Our friends W (the one with the wide-angle lens) and T (with the telephoto lens) are taking a picture of a tree so that it appears the same size in both sensors (layer A).

The house in the background (layer B) fills about a third of the frame for W but still almost the full frame for T. No wonder it looks closer. Since cropping has the same effect of reducing the angle, pictures 2 and 3 show the same compression effect.

I assume that the confusion about perspective compression stems from the fact that the idea of a wide-angle lens is to get close to the subject, so the wide angle effect hits. Per se, the focal length has nothing to do with it (at least ideally).