Looking for a compact body for travel. Would prefer an optical viewfinder over an electronic one if possible, and one that has great ISO performance in this segment. Don't know if I am asking too much but would be great if I can get clean images upto 1600 in low light conditions and usable upto 3200/6400. I don't know if such compact bodies come with fast primes, or fast zooms but a fixed aperture lens would be nice. Basically looking to replace my 5D3 when I want to travel light or just out and about. Any recommendations?