In a previous post, I was drawing a comparison between the Oly 45mm f/1.8, which I is loved by so many, and the Cosina Cosinon 55mm f/1.4 (which very likely is the better lens, despite being fully manual).
I wish to continue the discussion on "long" lenses for mirror-less systems vs. legacy glass of normal length. The Cosinon was just one example. More comes to mind, e.g. the classic 35mm f/2.8 wide angle, found in every camera bag 20 years ago. For APS-C bodies, this would be a decent normal, for MFT, such a focal length reflects a mild telephoto lens.
A 28mm was rather extreme in the days of 135 film. Those lenses are found less often in camera bags, however, those are still pretty cheaply available 2nd hand. While in MFT, 28mm transfer into a normal, in APS-C creates a field of view of a mild wide angle lens.
Here comes the advantage of adapting those old lenses to modern systems: being designed for 135 film, i.e. "full frame", those lenses produce very little distortion on crop size sensors. The prize of which being larger dimensions of the lens-barrel (and manual operations).
Back to the initial remarks about my friend's comments. When buying lenses for my various systems, I do focus on wide angle lenses for those systems, since the stock of legacy glass I own covers normal to tele-photo already. So, why would I spent more money for getting the same for a higher price?! Does not make much sense, eh?!
Here I am, having a decent collection of manual legacy glass, which suites me perfectly for normal to tele-photo, while wide-angle for the mirror-less systems is simply not available from legacy stock.