Originally posted by ElJamoquio Mirrorless lenses have claimed-to-be-smaller but the ones on the market certainly haven't been much smaller if any.
Actually, there are some smaller mirrorless lenses on the market. Panasonic is the market leader here, with two pancake primes and two pancake zooms. The problem seems to be that many mirrorless aficionados are afflicted with a kind of schizophrenia. On the one hand, they are constantly bragging about the reduced size of mirrorless cameras, but on the other hand they suffer from a constant lust for faster lens, including fast telephotos and zooms. Fuji just released an 18-135 f3.5-5.6. It's 100 grams heavier than the Pentax version. But that's not what the Fujinistas are complaining about. On photography forums there's a tremendous amount of histrionic tearing of hair and gnashing of teeth over Fuji's decision to introduce another "slow," variable aperture zoom. Some of the most extreme fast lens advocates have even gone so far as to insist that the Fuji 18-135 should've been an f2.8 constant zoom! Imagine what that lens would weigh, or how well it would balance on an XT-1!
Curiously, this lust for fast glass seems to arise, not so much from a desire for narrow DOF (although that sometimes is the case), but merely from a kind of tripod-phobia. In the majority of cases, these photographers want fast glass for hand-hold shooting in low light.