Creating tilegraphics in 3ds Max

I don't know if this is the right section, but I can't really find a 3D graphics section on Flashkit. Still, I think this problem is most commonly encountered in game development. Feel free to move the thread.

I've started a tilebased game and decided to experiment with 3ds Max to create tiles for it. The thing is that I want my tiles to have an exact size, in pixels. I've set up an orthograpic camera in 3ds max and started cropping the image so it contains just the tile. The problem is that when I use cropping I can't control the exact dimension of the output, as the output settings apply to an uncropped image. Now I can go and experiment which settings I need to get the wanted dimensions, but I'd rather hear that there's a better way then trial and error.

EDIT:

I guess the game explains the situation a bit better. WASD to move, space to jump.

WORK IN PROGRESS