In fact APS-C sized sensors (found in cameras like the C300, 7D, etc.) are the closest digital equivalents to real 35mm motion picture film, so technically if you want to stay as true to 35mm cinematography as possible, you should be shooting on APS-C sensors (which have a crop factor of about 1.6 when compared to full frame).
Alternatively, the imminent 28-70mmF2.8 provides similar range, DOF and light-gathering with a weight of only 470g if you don’t need the mechanical focussing. I don't think the 28-70 f/2.8 is a suitable replacement for the 18-35 f/1.8 for several reasons: 28mm FF at APS-C crop factor is 42mm, while 18mm APS-C is 27mm.To translate, a photo taken on a crop sensor Sony a6000 at 24mm f/4.0 1/200 sec with a full frame designed lens will produce more-or-less exactly the same photo as a photo at 24mm f/4.0 1/200 sec on a lens designed for the crop sensor. The crop factor means nothing if you're only looking at using a full frame rated lens on a crop body. The first recommendation for focal length for cropped sensor cameras is the 35mm. On a cropped sensor, the 35mm will act like a 50mm focal length. This is good for overhead shots and flatlays. If you ever did upgrade to a full-frame, it wouldn’t be a lens that you’d use much for food photography other than photographing restaurants.