The crashes of experimental manual_lens branch were caused by one of recent commits, so for my testing i've used build from Alessandro -
https://bitbucket.org/aprofiti/magic-lantern/downloads/My versions of lens.lua (+ xmp.lua, logger.lua and ui.lua) are not available anywhere except my notebook and camera.
Apparently the Sam 85/1.4 should be supported by ACR, but the question is, what they expect to be in exif data. Would it be possible to get some archive with lens profiles from ACR? I got one from Lightroom, but Samyang is missing there

My version of lens.lua works in a way, that you:
- select "exiv2" output format (instead of XMP sidecar for each pic it will append a line with exiv2 commandline to file named MANUAL.SH in the picture folder on SD/CF card)
- run "bash MANUAL.SH" (on linux-like systems, of course. with windows it'll be probably a bit different), which will update exif data of all pics
- open the raw/jpeg in your favorite editor
- profit
The point is to find the right lens parameters for the editor to correctly detect the lens and match it with lens profile it supports..
So far i have these in my list (and with this make+name the distagon worked correctly as you've seen:
lenses = -- {{{
{
-- The following is for testing purposes. Comment out the following lines then either uncomment only the lenses
-- that you want to use from the list or add your own lenses. Tip: Put your most used lenses at the top of the list.
-- Attributes to use:
-- name -> Name to be showed in Lens Info and in metadata
-- focal_length -> Current focal length to be saved in metadata (Zoom Lenses: Default value to be used after selecting lens)
-- manual_aperture -> Selected Aperture of the Lens
-- aperture_min -> Min available aperture for a lens (limits the available FNumbers to the min-max range)
-- aperture_max -> Max available aperture for a lens
-- focal_min -> min Focal Length (optional for prime lenses)
-- focal_max -> max Focal Length (optional for prime lenses)
-- serial -> Lens Serial Number (optional)
-- f_values -> Available f-stop for selected lens (optional) f_values = {"2.8","4","5.6","8"}
-- FminL -> Max aperture on short end
-- FmaxL -> Max aperture on long end
{ make = "Carl Zeiss Jena DDR", name = "Tessar 50mm f/2.8", focal_length = 50, manual_aperture = 2.8, serialN = "8333263", aperture_max = 2.8, aperture_min = 22 },
{ make = "E. Ludwig", name = "Meritar 50mm f/2.9", focal_length = 50, manual_aperture = 2.9, serialN = "1610554", aperture_max = 2.9, aperture_min = 16 },
{ make = "Helios", name = "44-2 58mm f/2", focal_length = 58, manual_aperture = 2, serialN = "7765411", aperture_max = 2, aperture_min = 16, f_values = {"2","2.8","4","5.6","8","11","16"} },
{ make = "Industar", name = "50-2 50mm f/3.5", focal_length = 50, manual_aperture = 3.5, serialN = "7149595", aperture_max = 3.5, aperture_min = 16 },
{ make = "Industar", name = "61 L/Z (MC) 50mm f/2.8", focal_length = 50, manual_aperture = 2.8, serialN = "8707286", aperture_max = 2.8, aperture_min = 16 },
{ make = "Meyer-Optik Gorlitz", name = "Telemegor 180mm f/5.5", focal_length = 180, manual_aperture = 5.5, serialN = "1728275", aperture_max = 5.5, aperture_min = 22 },
{ make = "Meyer-Optik Gorlitz", name = "Trioplan 50mm f/2.9", focal_length = 50, manual_aperture = 2.9, serialN = "2224344", aperture_max = 2.9, aperture_min = 22, f_values = {"2.9","4","5.6","8","11","16","22"} },
{ make = "Pentacon", name = "auto 29mm f/2.8", focal_length = 29, manual_aperture = 2.8, serialN = "6308110", aperture_max = 2.8, aperture_min = 22 },
{ make = "Pentacon", name = "Prakticar 50mm f/1.8 MC", focal_length = 50, manual_aperture = 1.8, serialN = "7710425", aperture_max = 1.8, aperture_min = 16 },
{ make = "Samyang", name = "85mm f/1.4 AS IF UMC", focal_length = 85, manual_aperture = 1.4, serialN = "A217D0264", aperture_max = 1.4, aperture_min = 22 },
{ make = "Zeiss", name = "Distagon T* 2.8/25 ZF.2", focal_length = 25, manual_aperture = 2.8, aperture_max = 2.8, aperture_min = 22 },
-- { make = "", name = "", focal_length = , manual_aperture = , serial = "" },
} -- }}}
There is still a problem with chipped adapters, which (from camera's point of view) behave as regular lens - with focal_min = 1, focal_max = 65536, F_numbers = { "1.4" }. Which means, that our attempts to set the focal length and aperture are stubbornly ignored by the camera when the metadata are written. With dumb non-chipped adapters it's all fine and the camera accepts values we fake with lua script.