This is one amazing lens. Amazing, because as of now, there are not many alternatives in the consumer market. Only since recently, Nikon has a 19 mm tilt-shift lens in its range. The widest tilt-shift lens offered by Samyang is 24 mm wide, Canon also has a 24 mm tilt-shift lens. This one is 17 mm, which on full-frame cameras means ultra wide-angle. An ultra wide-angle prime lens is nothing special, but this lens also has a tilt-shift mechanism, which allows you to manipulate (or rather correct) the perspective. The tilt-shift mechanism moves the lens elements relative to the image plane (this movement is called tilt) or parallel to the image plane (this is called shift). You can also combine both types of movement.
A tilt-shift lens can be used for a variety of purposes. I use the TS-E 17mm F/4L mainly in architectural and urban photography to achieve wide-angle perspectives with straight vertical lines (with no falling buildings, or so-called keystone effect). This lens is also fantastic when you photograph interiors.
You could ask: “Why would anyone spend over 2000 euros / dollars on a wide-angle lens, when you can correct the perspective in Lightroom or Photoshop?”. This is a fair question and I asked it myself when I first saw this lens in 2009 or 2010. When you correct the perspective in software you always lose some resolution. With ultra wide-angle lenses the amount of necessary correction is quite significant and therefore you lose quite a bit of resolution. You could say: “Modern cameras have enough megapixels and if you need more resolution you can always stitch several photos.” Yes, but can you do the same with time lapse or real-time videos? No, you can’t. That’s why I called this lens amazing. I bit the bullet and bought this lens before my first trip to Japan in 2012 and I have never regretted that. Below you can see sample images taken with this lens.
The TS-E 17mm F4/L is not a lens for everyone. It is a beast. It is relatively heavy and because of the bulbous front element it requires special care. It is not possible to use screw-in filters on it, but there are some adapter rings for square filter systems. It takes some time to learn how to use this properly, but once you learn it, this beast will produce fantastic images and videos for you that no other lens could. Highly recommended!