I can't tell you much about coatings but I can tell you that a lens I
find myself consistently commenting on is the Yashainon 50 1.4 DX. Every
time I view photos taken with this I just love the warmth of the shots.
Don't know how else to describe it. It is a very deep lens and using it
on an old Pentax Spotmatic I have to use a ring to keep it out about 1 mm
so I lose infinity but I can still do a lot with it and it is great for
portraits and for inside museums where they do not allow flash. It is one
of only two lenses I will be taking with me to Italy in a few days.

I've had a little trouble figuring that one out myself but will share my observations with you...

Yashinon-DS appears to have a single coating on both the front and rear optics. The focus grip
is a little rubberized ring that has a tendancy to come unglued and and either slips when trying
to focus or comes off and gets lost.

Yashinon-DS-M is the multi-coated designation for their lenses of this period. Physically
it looks like the DS version above. I have one DS-M lens and will never part with it. An
exceptional lens with great focus, contrast and color rendention throughout its f-stop range..
Also rare and hard to find.

Yashinon-DX also appears to have a single coating on both the front and rear optics.
The focus grip is a machined metal surface. The DX also has a switchable Auto <->
Manual setting that the DS version does not offer. I think this is a better looking lens
than the DS version and will sometimes be found with a chrome front filter ring.

I've never run across a DX-M but wouldn't be surprised if they are out there somewhere.

Ken