I don't think the article is taking into account focal length. A 600mm lens will weigh more than a 100mm lens. Maybe the mirrorless MFGs began with 50, 120, 200mm models and finally getting some quality 400 and 600mm lenses out there which are going to affect weight.
And aperture. I'd love to see weight graphed against aperture and focal length (I guess it'd be a 3D plot), and then see what the correlations are. Does weight increase linearly with focal length? (I'd guess so.) Does it increase super-linearly with aperture? (I'd guess there's a square in that relationship.)
Certainly non-linear (in weight as well as price). Where you have roughly comparable lenses with, say, f4 max aperture (or a zoom with variable f4.5/5.6 or something like that) vs. an f2.8 fixed or zoom.
A good example is Canon 70-200mm.
EF 70-200mm f/4L USM is ~$600 and weighs 705 grams. (This is still a very good, fairly high-end lens.)
Compare to:
EF 70-200mm f2.8L IS III is ~$2100 and weighs over twice as much.
And certainly there are cheaper/lighter (and slower) third-party 70-200mm full-frame zooms and even smaller ones for APS-C sensors.
Along those lines, I use an old 1980s Nikon 70-200mm f/4 as my "long" lens. It weighs about a quarter as much as the modern f/2.8 version. I'll gladly give up a stop I don't really use anyway for something that doesn't feel like I'm lugging a howitzer around.
While the new ones benefit from lighter materials construction, the Nikons at least have vibration reduction built into their lenses rather than sensor also autofocus [in the lens] adds weight vs mechanical. So, on the one hand materials are getting lighter, on the other hand they've added tech which has added weight.
Nikon transitioned from AF motors in the camera to AF motors in the lens, which added weight to the lens (and removed weight from certain low-end consumer bodies). The lens I use has AF, but uses the body's motor.
I don't really care about vibration reduction, stabilization, or any of the other modern sharpness-obsession gear. I'm still shooting a D7000 I've had for close to a decade. For what I'm trying to express, more resolution and sharpness has never really helped.
Maybe the mirrorless MFGs began with 50, 120, 200mm models and finally getting some quality 400 and 600mm lenses out there which are going to affect weight.
This is absolutely true. Check the release history for Olympus lenses - the 40-150mm Pro and 300mm Pro were two of the most recent releases. Both are relatively massive by micro-4/3 standards.
And the most recent releases were the prime f/1.2 pro lenses, which are seriously hefty and massive. The 25mm (50mm FFE), for example, is 410g. Contrast with the pancake Panasonic 20mm f/1.7, which only weighs 100g -- less than a fourth as much!
