Same visible area with every resolution

Hey,

I am making a game whre you look at the map directly from above (orthogonal). It's not a map where you can scroll around, it's only one map that fixes in the screen, and here is the problem.

The map is for example 100x75 units big, what means 4:3 and fixes in the screen. If I start the game in another resolution that is for example 16:9 you can see "the nothing" on the left and right.

Is there a solution for this? Maybe like stretching everything or just change the width of the camerafield?

I also tried the code from > here < and put it on the camera but it didn't work / solve the problem.