The Sony A7 and A7R have Sony's 'Multi' connector on the side by the HMDI port. This multi connector can be used with the Sony 27-RMVPR1 wired remote. But... what if you want to trigger the Sony A7/A7R by RC or some other remote device? No problem. A bit of modification work to the remote and we can make it work. Pics of the modification in the gallery below.
Disassemble the remote by removing the screws on the back cover.
Remove the cover and you'll see the PCB. There is one screw holding the PCB to the front cover. Remove it so that the PCB can be removed entirely.
Now we will add a 2.5mm female jack to the inside of the remote housing. There is just enough room to fit a small jack available from Digikey. Part# CP-2523SJCT-ND. You'll need to drill a 4mm hole in the side of the remote housing where the jack will be placed. You only have one change to get the location correct so drill carefully. It's smart to first drill a pilot hole about 1/8" (3mm) first then open up to 4mm.
You'll need to then chamfer the edge of the hole in the housing to allow the male 2.5mm plug to fit in. Failure to chamfer the edge will prohibit the plug from fully engaging the jack due to the wall thickness of the remote housing. Carefully place the jack in place. Put a bit of super glue to hold it in place taking care not to get super glue inside the jack.
Now we need to solder some small wires to the switch pads on the PCB. Use some very thin flexible wire. 28 gauge is what we use. Solder to the shutter and focus switches as shown.
Now solder the other ends of the wires to the 2.5mm jack.
Now close it all back up. There's just enough room to fit the wires in cavity in the housing next to the shutter slide switch.
Now with this plug you have direct access to the focus and shutter points. You can make a 2.5mm cable adapter to interface with an RC switch or other switch/button device.