Leveling posts ?

[Highbeam]

A rotary lazer level with tripod and everything is only about 400$ at the home depot. You will use it more than you know for all kinds of things.

I got one for installing drainage pipes and have since used it for drainage ditches, site grading, and setting up my own pole barn.

A guy borrowed it for installing cabinets too.

 

[massey990]

Unless you use a laser to set at your "cut line" where you can mark each post you might want to set a "control line" by marking the corners and use a string to mark intermediate posts. Set a control line at a moderate working height say at shoulder level, then you can cut a thin straight stick etc. that is the exact length above the "control line you want to make your cuts. Attach the stick on each pole to mark your cut line.

Using something like a water tube level will work great but again I suggest only marking the corners and using a string to mark intermediate posts, this cuts down on slight errors that can occur. Using a tube level will work best if you set each mark leveling from the original grade, marking one post and moving both ends of a (short) tube level will compound any errors.

This observation comes from my days as a surveyor where we layed out and set grades on many stilt homes and pole barns.