For such a great lens, it's amazing it is not more widely owned. Often seen as a candid portrait lens, the EF135mm f/2L USM is about more than just catching people when they're not aware. If optical quality is what you're after, then it doesn't get much better than this. It is sharp. Tack sharp, pin sharp, razor sharp, whatever you want to call it, it's it. It is also fast, both to focus and in terms of aperture. The f/2 allows you to shoot in low light and control depth of field like nothing else. You can separate the subject from the background and get fantastic bokeh at the same time. It's also light and compact making it easy to carry. If you shoot portraits or low light, you really shouldn't leave home without it. As if that wasn't enough, it takes an Extender too - 189mm f/2.8 or 270mm f/4 anyone? Yes, it really is a versatile piece of glass. Does it have a downside? Well, it'd be nice if it had an Image Stabiliser but you can't have everything. Otherwise this lens is pretty much perfect. It has one other use too, one that's a little less important photographically, but useful none-the-less. Since it's quite an uncommon lens to see and not the first lens people think of when buying new glass, it's a good way to pick if someone follows the crowds or not. I tend to find, if I see someone with a 135 f/2, they probably have a good idea of what they're doing - you might even call it a connoisseur's choice! If you've never shot with one of these lenses, go out and give it a try - find someone who has it, beg, borrow or steal it and prepare to be amazed at how this seemingly forgotten L lens can open up so many opportunities for you.