Mittenwald is the German hometown of luthiers, much like Mirecourt in France. They're well documented.
"Schmidt Ernst Reinhold; Markneukirchen. b. I. 1.1857, d. 22. 5. 1928.
Pupil of Wilhelm Julius Kretzschmann who worked with Otto Bausch, J. F. C. Emde, and Heinz Hammig.
Between 1874-1877 he was with August Anton Riechers. In September 1880 he founded a prosperous factory, E. R. Schmidt & Co., of which he became sole owner in 1902.
On 1.1.1903 the firm was dissolved, but Schmidt continued in the trade.
After 1920 he was joined by his son Reinhold Willy S., who was as skillful as his father.
Instruments produced by this factory were highly esteemed as 'Schmidt's Standard' and were awarded gold medals at the Vienna Exhibition of 1892 and in Leipzig in 1913.
Schmidt Standard or Tartini labelled violins are trade or "Dutzendware", spirit finished. The better ones wear an inside stamp E.R.S., oil varnished.
The instruments bear the label of the firm, which also made lutes and mandolins."
E.R. Schmidt was located in Markneukirchen, not Mittenwald. They may have had an office there to bank on the name of the location.