The Sony A7 series is a phenomenal camera for hobbyists and professionals alike. The A7s have a full frame 35mm sensor and interchangeable lenses. Sony's mirrorless technology allows for a super lightweight body by removing the traditional Single Lenz Reflex mirror-based viewfinder system, and replacing it with a digital monitor. This adds a tiny bit of delay so it's not ideal for sports and action photographers. However it does allow for an accurate image preview while you adjust F-stops and shutter speeds before snapping a shot.
These cameras perform amazingly in low-light settings, have RAW capabilities, and capture professional video. They are compatible with Sony's E-mount lenses natively and several adaptor kits are available for attaching lenses from other manufacturers.