As far as extreme lenses go, Canon's 200mm f/2L IS USM is near the top, with one of the most extreme focal length and aperture combinations out there. Though it was generally designed as a sports and wildlife lens, it has found a second home as a portrait lens, and this fun video discusses what it is like shooting with it, both the pros and the cons.
Coming to you from Manny Ortiz, this neat video takes a look at using the Canon 200mm f/2L IS USM lens for portraiture work. At $6,000, the 200mm f/2L is mightily expensive for a portrait lens (or any lens, really), but a fair number of photographers swear by it, as its unique combination of a very long focal length, extremely wide maximum aperture, and jaw-dropping image quality create photos in which the subject instantly pops out against the background. The downsides to the lens besides its price are its huge size and working distance. It takes a lot of glass to create such good image quality at 200mm and f/2, and as such, the lens is very heavy and not really easy to handhold for very long. And at 200mm, it can be a bit difficult to work with subjects due to the long working distance. Still, it can create some truly unique and stunning images. Check out the video above for Ortiz' full thoughts.
It's my favorite lens and I use it for every single portrait shoot that I do. But then again I'm a bokeh whore.
it seems manny finally learned to balance flash and daylight... :D
Here's a solution to the size and weight of a 200mm fast prime lens for portraits - switch to DX/APS and use a 135mm prime ! 1.5 x 135 = 202.5mm, which is the same as a FF 200mm with a hint of focus breathing !
If you can't afford an F2.0 there are loads of legacy 135mm / F2.8's out there to adapt.
Even at F2.8 you get the 2 important features of these lenses
[1] the ability to "close down" the background to a single colour or shade or pattern behind the subject and simplify the composition
[2] background blur - trust me, you still get plenty of bokeh at F2.8 with a 135mm / 200mm EqFF
and then the added benefits - the size and weight are halved and the costs quartered - or even more if you find a legacy lens secondhand on an auction site or thrift store (and = there are plenty to buy as lots and lots of 135mm lenses were sold in the film era !)
Cropping a problem? No, 8MP is all you need for a sharp 12x8, so most cameras can afford to give away the crop to DX/APS without letting you lose a great photo opportunity.
Yes I too have a huge fast 200mm full frame that I got new - but it still looks mint because...like for Manny ....it is nearly always in its box at home!