I'm one of those (many, I suspect) considering the a7/a7r for my ample collection of Leica M lenses. (I have read and accept some of the wide-angle limitations but as I rarely go wider than 35 mm, I'm not too concerned.)
But I'm puzzled by the adapters available. The Metabones is $90, the Novoflex is $270, three times more expensive.
What's the diff? Neither has any optical elements, so why such a wide disparity in price?
Recommendations received with gratitude!