I would like to generate a group of images of different views of a 3d object using one of these softwares, blender, maya, 3ds max.

Is there anybody so kind to tell me how to change the camera's principal point and focus in a convenient way? Is there a existing panel for setting this parameters? Or I should build some external plug-in to set them?

In Blender, a Camera is just another Object. You can drag it around, you set the values via the UI or programatically with Python, you can look thru it to aim it and you can switch between the cameras in a scene.

Thanks for your reply.
Is there an parameter in the UI of current version of blender for changing the principal point?

stiv wrote:

In Blender, a Camera is just another Object. You can drag it around, you set the values via the UI or programatically with Python, you can look thru it to aim it and you can switch between the cameras in a scene.