Ricoh doesn’t use m43 sensors AFAIK, so that would probably have to be an APS-C camera. Because of the sensor size and the f/2.8-4 you want, that lens would be a LOT bigger than the GM1 zoom …
DPReview Gear of the Year Part 2: Panasonic Lumix DMC-GM1
Posted by Chris Roubis on 20th, Nov, 2013
Source Article from http://www.dpreview.com/news/2013/11/20/dpreview-gear-of-the-year-panasonic-lumix-dmc-gm1
Started out doing photography at the age of 6 using an uncle's old 1940 kodak brownie box camera. At 15 years of age, I decided to buy my very own 1975 Praktica SLR camera. I now shoot with a Nikon D850. I do unpaid TFP and commercial paid work.