Wide lenses are the difficult to use well. Ultra wide lenses
even more. They are actually not for getting everything into the frame, but for
giving the viewer the feel that he experience to be into the middle of the
action. They are as well called Fisheye lenses and they are just plain fun.
I had a chance to get hold of a 180-degree field-of-view lens which I tried out today. It is a joy just to point at various things — it is almost impossible to miss any action in front you.
The lens I got is an 8 mm Fisheye lens with an manual aperture ring — its smooth adjustments while shooting video make a difference compared to the abrupt clicks of most apertures. The lens doesn't communicate at all with my camera, which make it full manual, but using it with the Sony NEX 7 its fun nevertheless.
Using them properly, you should be rewarded with dynamic images like putting the muzzle of a revolver right in your face. There is a caveat If you can't or are to shy to get close, real close – it’s not a lens for you.
Ultra wide lenses should push the viewer's nose into the image. They are not for the faint of heart. If you are out jamming the lens into the face of enraged and crazy people might get you apart from dynamic images as well some other difficulties.
It requires to get exceptionally close and personal to anything you are pointing the lens at. Even a fraction of an inch can make a huge difference in composition, so a lot of practice is needed.
You will get plenty of drama in trees and clouds, which are normally innocuous, and there plenty of distortion as well. Think of ultra wide lenses as the opposite of tele lenses where you tend to back away from objects.
If your camera is even slightly out of the horizontal, verticals will converge. Buildings will develop leans, which add a sense of drama to otherwise dull scenes. If you have a chance to try don’t hesitate. I’m still working on it. Here some examples I did in b/w and color.