My wideangle craze
I have loved wideangles since I got my first real one
Ever since I fooled around with my first 24mm I have had a soft spot for wideangle lenses. Should I select one focal length to bring to that famous deserted island, it would be a 20 or 24 mm prime (35mm equivalent) with a good smallest aperture, like 2.8 or even 1.8 or 1.4 as it's possible in the latest 24mm offering from Nikon.
The wideangle gives me the closeness that I like in pictures, and eneables me to get really great perspective as a bonus. Depth-of-field will usually be good, and the options of composing by tilting the camera and putting stuff closer to the corners rather than in the middle and still get everything in there is a blessing. Wideangles taught me to use the rule of thirds, the golden ratio and the concept of composition using perspective and vanishing lines.
Personally I consider a 35mm a normal lens with a bit of angle. To get real wideangle-effect I prefer at least a 28mm, preferably a 24mm and when we get down to 20mm and 18mm I feel I'm getting somewhere. And we're talking 35mm equivlant here, not APS-size sensors. If you have to take the crop factor into consideration, the fun starts at 18-20mm and 10-12mm is not bad at all.
Straight fisheye
A couple of years ago I acquired a Sigma 15mm fisheye, which I have had a lot of fun with. It's a full frame lens, and does wonders on a film camera with its 180 degrees diagonal angle. On a digital camera it's still a hefty wideangle, but it has the typical curved lines of a fisheye. The curves can be removed with a Photoshop filter, and I have used PTlens, which can be used to correct all sorts of lens distortions and vignetting.I have always been very much in love with Sigma's 14mm non-distorting wide angle, but never had the money to spend on it. With the 15mm and PTlens I get pretty close.