Sounds like you need a "Beachtek DXA4"

This is a box that sits between the camera and tripod and performs the function you want. And from my experience, performs it very well too.

Your trouble may come from the fact that you want it for two different cameras. They tend to come cameras specific because of how the camera mounts on top of it.

It does appear, though, that the price has increased since I got mine this time last year, sorry.

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