Powering Accessories on a Rialto 2

[LensMeAHand]

This week I was on a shoot where we used a Rialto 2 for some handheld shots because of its relatively light weight compared to the Venice 2. However, we ran into a problem mounting a follow focus and monitor on the Rialto 2. Here's the issue—there's a 24V output on the front of the Rialto 2, but our monitor and follow focus ran on 12V, and we didn't have a step down converter. 

If you haven't used the Rialto 2, you might be confused when nothing comes out of the 24V output on the front of the Rialto 2.

Looping power and video to make use of the Rialto 2's outputs

You have to loop power and video ouputs on the Venice 2 in order to get anything out of the front outputs on the Rialto 2. And with that in mind, we realized you don't actually need to send 24V through the 24V connection. So we built our own cabling to run 12V into the Rialto 2.

The 2-pin Lemo connected to the Venice 2's 12V power, and the 3-pin connected to the 24V input that ran to the Rialto 2

The 3-pin Lemo carried the 12V from the Venice, and the D-Tap split off to the monitor & follow focus

There are three things to keep in mind about this setup: (1) a 24V to 12V step down converter would be a much better solution, as you would have twice as much amperage, allowing you to power more accessories. (2) if you also find yourself in this pinch and decide to go the custom-cabling route, make sure you connect ground to ground on the 3-pin lemo or else you run the risk of shorting out the camera.

Pinout for the 3-pin Lemo on the Venice 2 

And (3), these are dangerous cables to have. So if you build them, you should mark them as such, so that someone doesn't unknowingly fry an expensive piece of camera gear down the road.

[alisterchapman]

Just be careful doing this not to exceed 2 amps as you can damage the cable. When you run 12v instead of 24v the maximum power than can be passed own the cable safely is halved. At 12V you have a maximum power draw of around 24W but at 24v you have 48W. It's better to put any voltage converters at the output from the Rialto rather than at the camera body end.