Sony A1 II has a
50.0MP Full frame (35.9 x 24 mm ) sized Stacked CMOS sensor and features Dual Bionz XR processor. On the other hand, Sony A7R has a
36.0MP Full frame (35.9 x 24 mm ) sized CMOS sensor and features Bionz X processor.
Sony A1 II's sensor provides 14MP more than Sony A7R's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
One other difference between these two cameras that is worth mentioning is that Sony A7R's sensor doesn't have an anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the A1 Mark II and A7R sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A1 II and Sony A7R Cameras
Sony A1 II and Sony A7R have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Sony A7R has 37% larger pixel area (23.83µm 2 vs 17.31µm 2 ) compared to Sony A1 II, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Sony A1 II
or the
Sony A7R ,
including hyperfocal distance.
