It was not all that long ago that I had little use for focal lengths shorter than 50mm. I was always thinking about getting an even longer telephoto lens. For what? I was never really sure, as I have little patience, and even less ability, for photographing things that move (with the possible exception of cats). Worse, I always thought of myself as a landscape photographer. So this fixation with long focal lengths was probably just a case of misplaced megalomania. At some point, and as far as I can tell this happened essentially overnight, I figured out what was wrong. It is not the size of the lens what matters, it is the size of the landscape that you can fit in the sensor. Ergo, I had it backwards. The shorter the focal length, the better. Since that moment when I saw the light I have become obsessed (never one to do things half way) with wide angle lenses. Today I have what I think is a reasonable collection of manual focus wide angle lenses (and some wide angle digital lenses too), and a significant proportion of my photography revolves around them. I do still have some focal lengths longer than 50mm, and I do use them, but that will be a topic for another day.
The OM Zuiko 18mm f/3.5 is the widest corrected lens that I own, and it is a good place to start talking about super wide angle lenses. As all high-end Olympus lenses, it is a small jewel. The mechanical perfection is watch-like. The solidity and heft make it a joy to handle. And the optical performance is excellent. Much has been written about the fact that it is truly distortion-free, a remarkable feat of engineering given its tiny size. Coupled to a full frame sensor (Sony A7), the 18mm Zuiko rewards you with enormous landscapes that preserve a sense or reality. The human eye cannot encompass anywhere near what this lens can see. Yet, when you look at the images that this lens produces, they are remarkably realistic. They make you believe that it is perfectly possible to see those images in the real world. Why? The lack of distortion is almost certainly part of the reason, but I believe that it is not the whole explanation. The rendering of color, contrast and sharpness add up to a very natural feeling. Sweet and sharp, but not surgical. Classic Olympus. Combine these characteristics with the distortion-free perspective and you get enormous yet very natural-looking landscapes. It is sometimes hard to believe that those images could have been generated by such a tiny lens. Such is the magic of fully-corrected super wide angle lenses.
Mind you, the 18mm Zuiko is not a perfect lens. As a true Olympus fan, I wish I could say that it is, but it is not. It is not as sharp as the 21mm and 24mm Zuikos, nor the 21mm f/2.8 Hexanon – but these are all very high standards. The corners are not as good as the center, even when stopped down. On the Sony full frame sensor it displays quite severe vignetting, though above f/11 it is relatively easy to fix in post processing. And, at least my copy shows a subtle green/cyan tinting towards the edges, which again is in most cases easy to remove during processing. But who cares? The images that it generates can be sublime. It may not be perfect, but it is a great lens. Judge for yourself.