Quote:...however I am not sure how easy would it be to manually focus using this lens ...
It really depends on what you are going to use the lens for.
Once you have figured out where infinity really is (note, that
the correct setting for infinity is not neccessarily at the point
where the infinity mark is on the scale) and if you additionally
know the 1mtr point ... the rest is quite easy.
For moving subjects this lens isn't really usable.
The 14mm Samyang has quite a bit distortion which needs to be
corrected if you're using it for anything with straight lines ...
nevertheless this is usually not a problem (but depending on the
SW you use for processing your images).