You can buy good gun with optical sight for this money.
Interview in Japanese about this lens
http://dc.watch.impress.co.jp/docs/news/interview_dcm/20160219_744033.html
Sharpness is of a very high order. At f/4 the lens is very evenly matched edge and center and delivers excellent sharpness, bordering on outstanding. At f/5.6 results are truly outstanding right across the frame, with an impressive set of figures that are virtually identical center and edge.
https://www.ephotozine.com/article/olympus-m-zuiko-digital-ed-300mm-f-4-is-pro-review-28917
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