@romullus and everyone interested in decent looking barrel and fisheye distortions - custom texture distortion maps are a way to go if you want to get a decent and non pinhole like ones the cubic one produces - after studying this
https://knowledge.autodesk.com/support/3ds-max/learn-explore/caas/CloudHelp/cloudhelp/2016/ENU/3DSMax/files/GUID-71FF38CD-07E4-419B-A8AF-69CE101182A0-htm.html and the provided sample I realized those distortion maps are in fact just a normal maps without the blue channel so it's not too hard to model a sphere representing the lens curvature, make a render from a 200 or more mm camera pointing straight at it like this
http://c2n.me/3HTMABp + making a zdepth pass with min distance just before the front of the sphere and the far one at around the point your camera view cone intersects the sphere - this way you get some nice displacement texture out of it (btw I use this simple method for any quick and effortless displacement map extraction) after that you just need to convert that displacement map into a normal map using any of the normal map making software out there (I prefer Knald) and voila - after some rotation and contrast tweaking you get yourself a nice normal\distortion map which can make
http://c2n.me/3HTNvbq distortions looking like 1 rather than the ugly 2 )) See the attached distortion map I made - to get the results similar to the one I posted, simply up it's contrast either in photoshop or by putting it through 2 ColorCorrection modifiers - 1st with a 100 contrast and the second one at around 55.
Anyway this method is of course not accurate in any way but you can make ANY kind of distortion maps this way, even some funky and totally unrealistic ones just be aware that those maps should have the same image aspect\proportions as the render resolution has - that particular one I made is made for 1.0, well 2000x2000 etc .
edit: To think of it - probably some simple displacement map made in photoshop by using some of the round, blurry brushes and using white color to paint over a black background will work just as well as the displacement map extraction method I mentioned above - well, anyway, the more the merrier ))