Canon5Dtips Photography is more than words.
This project might not be for everyone but if you are like me and have trouble keeping the sliding motion at a constant speed, here is a solution: automate it! Martin Koch had the same issue has me and solved it the geek way: by using an Arduino and a stepping motor.The detailed explanation can be found on his blog. While the given version is too weak to carry an HDSLR, you just have to upgrade the stepping motor and you will be set.
You can see the results in some sequences of this clip.
