Depends on the camera, but it is a jump. Some 4x5" field cameras like the Deardorff 4x5" Special and cameras built on that model are really 5x7" cameras with 4x5" backs, so 5x7" cameras often feel like big 4x5" cameras, but with 8x10" the camera is bigger and the filmholders get notably bigger, so you'll likely be carrying less film and shooting more deliberately in the field.