camera FOV setting

I have a multi-layer object with two different shapes, and I want to set a camera with each of them. (see figure 1)
Is that possible for camera only presenting a single circle shape without background? (see figure 2)

(figure 1)

(figure 2)

If I understand you correctly you want a certain camera to only ‘see’ certain Geo objects.
This effect is currently only possible using Render Pass TOPs.

You first create a Render TOP, and set it to the first camera and the first geometry you want to see. Then add a Render Pass TOP, and drag your Render TOP to its renderinput variable. First enable ‘clear to camera color’ to remove all content added in the previous pass by the Render TOP. Then set this Render Pass TOP to the second camera and only the geometry that should be rendered from that second camera viewpoint. Etc for the other cameras.

yeah! It does work! thank you so much!!!