Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I would think that the pictures from the A7R are low-resolution.
Low-resolution can result from these causes (not listing the 'low-res' that results from swiping the camera mid-exposure and producing blurs):
1. lack of sharp focus
2. low resolution settings on the camera - a feature only digital cameras have, of course.
3. ISO settings and/or dim light, a mismatch in short
4. or excessively low exposure settings combined with a less-than-ideal (3) above too.
I suggest that you check
A. the focusing on your A7R. Do Manual focusing at least for a test shot, make sure it's quite sharp in Viewfinder or in Live View mode, before shooting.
B. the resolution setting on the A7R. Set it to Maximum resolution in pixels.
C. and obviously, double-check your ISO and exposure time and lighting ( the things I hardly need remind you of, obviously. Sorry to have mentioned them.)
I suspect that either you need to do a Factory Settings Reset on your camera (to obviate some hidden setting combination having a bad effect on resolution of resultant photos), or you have a defective camera, or possibly you have a low-resolution setting on the camera i.e. less-than-maximal resolution settings or 'Quality' settings.
Focus? if you get sharp focus through viewfinder or Live View when Manual focusing, then probably the optics are good enough. A Focus defect would be optics (unless Auto Focus had a problem, of course.)
Let me know your thoughts, and also whether you need instructions as to Resolution/Quality settings on the A7R camera, or instructions as to trying a Factory Settings Reset.