The Canon EOS 600/630, 620, 650, RT camera bodies are able to use interchangeable grips, GR10-L, GR20 and GR30. The "standard" GR20 and GR30 grips are similar in size but the GR20 has a T3 shutter release socket, the GR30 has none. The GR10-L is a much larger grip, but has no shutter release socket.

I modified a GR10-L by installing a 2.5mm (3/32") 3-conductor socket which is connected to wires positioned to interface with the 3 contacts on the camera body. The socket projects through the back of the lowest portion of the grip, facing about 45 degrees downward, making it convienient to hold the grip in my hand while the remote switch is plugged in. (see pictures below) Modification time: about 3 hours.

I also modified 2 GR20's by adding a 2.5mm socket to each. I kept the T3 sockets functional and added the 2.5mm jack to the bottom of the grips. This was a much easier modification because I just joined the 2.5mm jack's wires to the existing T3's wires. Modification time: about 1 hour each.

Why a 2.5mm 3-conductor socket? Because Canon uses the same on the Rebel X(S), Rebel G, and Elan II(e) camera bodies and markets the Remote Switch RS60E3 which uses a 2.5mm plug. I have found no source of T3 jacks (and I'm not sure that I even like them).

The camera body contacts I've labeled 1-2-3, with #1 being toward he camera's back (see figure 3): short #1 to #3 for the camera to focus and meter, short all 3 to release the shutter.

Canon's 2.5mm plug standard is:
________________
··1····|··3··|2 \ Where #1 is the"ground", #3 is the "ring" and #2 is
_______|_____|__/ the "tip", corresponding to #1, #2, and #3 on the body.

To install a "stereo" jack in a GR-10....

1. buy a 2.5mm panel-mount jack.
   • 2.5mm panel-mount jack: Philmore part #666JP, UPC: 0-38975-13666-0
     • 2.5mm in-line jack: Philmore part #666VP, UPC: 0-38975-13667-7
     • 2.5mm in-line plug: Philmore part #666PP, UPC: 0-38975-13666-4
2. disassemble the GR-10.
3. Locate where in the handle to install the jack.
   • I installed it in the 'bevelled" part. (see figure 1)
   • I had to grind away some of the lower "webbing" inside of he handle.
4. Grind plastic (under the metal piece) to position wires to mate with the body contacts.
   • Use a GR-20 as a guide.
5. Grind and drill plastic to route wires from the jack to the contact position. (see figure 2)
6. Solder wires to jack.
7. Route and trim wires.
   • Strip insulation from the camera contact-end and bend the ends so that an "elbow" from each contacts the body. (see figure 3)
8. Reassemble the grip.

Figure 1.

Figure 2.

Figure 3.