Or maybe he just sharpened them a bit in post :)
I never in my life did that to a render :- ) I only sharpen my photography.
To OP:
I am not sure if you mean more the "Haze" (from window glow) since you mention lighting, or Antialiasing, which does seem fine. It might be just that this particular angle gives such a feeling, but there might be no technical shortcoming.
Anyway, I personally, find anything less than 2.5k res soft. Which is why I render often pretty big renders, 5-8k, with soft (2-3px AA filter), which I keep in original resolution for printing, and downsample to 2k for Web&Social Media, which gives ultimately much nicer AA& Detail as if I rendered 2k originally. This might seem overkill for some, but for me it's utilitarian since I will need to high-res for nice print anyway.
I usually downsample using bicubic smooth, but our web I did exception and sharpened using bicubic sharpen, so I have 2.5k in sharpened state. You can see here :
http://talcikdemovicova.com/classic-apartment-by-jessica-vedel/Some few ideas:
1) Say no to high-pass. Never ever for archviz, it's the ugliest form of sharpening, it has very "thick" effect.
2)If you render anything under 2.5k, keep 1.5px Filter. Anything else might be too blurry.
2) Did you do denoising ? That can contribute a lot. I use denoising only for rather clean images, like under 2.5perc. of noise ratio. And even then, no more than 0.4 Blending.
3)Bump mapping. This is problematic with Corona, because too much will give you terminator artifacts, but too little will create unnaturally smooth surface. Everything has bump.
4)Texture filtering. Default 3dsMax is problematic. I am not sure if the CoronaBitmap is too much better...didn't do extensive test. But when you can, use the lowest (0.01) possible filtering. Even for bump, unless it gives you Terminator. Then write bug report, because we really need to get rid of it :- ).
5) Post-production that keeps
local contrast. This can be done by few methods, we need the blacks to be black, not overall s-curve. Filmic mapping has "shadow richness" parameter that boosts blacks, CameraRaw has selective blacks, etc.
..