Do Fast Lenses Matter Anymore?

bruxi wrote:

As I look at pricing for Canon 70-200L lenses, it looks like the price premium for a 2.8 is about $1,000 (average of IS and non-IS versions). A thousand bucks seems like a lot for basically one stop when new sensors are bring many more times that through rapid ISO improvements (like the 6D). There is so much more room now on ISO to crank it up with very little performance drop off. The notion of "fast lenses" feels more and more like dinosaur film thinking and makes very little sense to me from a value perspective.