I think that Einstein have covered the answer quite extensively but I just want to extend on his answer, if you are looking for an adapter from MD to MA, Minolta made an adapter named M/A converter, these adapters are 2x convertors at the same time, this is one which is available now from ebay
otherwise if you are using the lens only for macro then you should buy an adapter without a lens but you will lose infinity focus.
|Waffles with fruits by Coolinarka|
from Food photography (desserts)
|Vestrahorn Frozen Reflection by Will B Milner|
from Ice cold