There is discussion in various forums about shutter shock with Electronic First Curtain Shutter (EFCS) with the R7. I have been following this and have done careful tests of my own with charts and would like to sum up the situation. Shutter shock can occur when any shutter is opened mechanically and it causes a vibration, independent of whether the camera is mirrorless or a conventional DSLR, unlike mirror slap that can't occur for mirrorless. EFCS is designed to avoid this as the shutter opens electronically and closes mechanically, after exposure. But, it has been noted with the R7 in its high speed 15 fps drive for EFCS that the first shot is fine but that there is shutter shock for the subsequent shots. This appears to be because the shock of closing can vibrate the following shot. This doesn't happen for all lenses, the adapted EF 100-400mm II, for example, has been reported to be immune.
I have tested the RF 100-400mm, RF 100-500mm and RF 800mm f/11. In H+ mode of 15 fps with EFCS and mechanical shutter, there is noticeable shutter shock at lower shutter speeds that is nearly gone by 1/250s and completely absent at 1/400s. Electronic shutter has zero shutter shock as expected. In the H mode of 8 fps for EFCS, I couldn't see shutter shock at 1/60 s.
So the take home message is: avoid H+ mode for EFCS at /250s or slower and all mechanical modes at 1/250s or slower. Also, the R7 does have bad rolling shutter with ES, so avoid that when wings are flapping fast or panning fast against vertical lines. But, the R7 has a good variety of drive modes, the H+ mode is 30 fps for ES and 15 fps for MS and EFCS, the H is 15fps for ES, 8 for EFCS and 6.5 for for MS, and low continuous is 3 fps for all three modes, and so we have lots of choice for different situations. I leave the camera in low speed continuous ES for static shots, H+ ES for BIF and H+ EFCS for insects in flight etc where rolling shutter can be a disaster.
I have tested the RF 100-400mm, RF 100-500mm and RF 800mm f/11. In H+ mode of 15 fps with EFCS and mechanical shutter, there is noticeable shutter shock at lower shutter speeds that is nearly gone by 1/250s and completely absent at 1/400s. Electronic shutter has zero shutter shock as expected. In the H mode of 8 fps for EFCS, I couldn't see shutter shock at 1/60 s.
So the take home message is: avoid H+ mode for EFCS at /250s or slower and all mechanical modes at 1/250s or slower. Also, the R7 does have bad rolling shutter with ES, so avoid that when wings are flapping fast or panning fast against vertical lines. But, the R7 has a good variety of drive modes, the H+ mode is 30 fps for ES and 15 fps for MS and EFCS, the H is 15fps for ES, 8 for EFCS and 6.5 for for MS, and low continuous is 3 fps for all three modes, and so we have lots of choice for different situations. I leave the camera in low speed continuous ES for static shots, H+ ES for BIF and H+ EFCS for insects in flight etc where rolling shutter can be a disaster.