Hey Sasha Schiavi ,
Unfortunately you cant do this in-render (though that might be a sweet feature!).
After you render you would need to composite the images in Photoshop or other photo editing software. Import all the images (Background photo, Render, Material ID pass), stack them in photoshop, then select the background from the Material ID pass and mask that part out of the render. Then hide your Material ID Pass and you'll have what you are after.
Hey Ted.Vitale! Thanks for your reply.
I don't think I was clear enough when I explained my problem.
Yes, I understand what you're saying about needing Photoshop to compose the image after rendering. That's how I usually do it. And I use the render channels to make my life really easy.
But my problem is, that even when I render, enscape changes the image's depth of field to what ever I have it set to in the Rendering Tab of the Visual Settings menu. The view Synchronization and the Use Viewport Aspect Ratio don't seem to work for getting the camera position and field of view exactly as I have it in sketchup.
I'm working around it by trying to match the depth of field of the image by flicking View Sync on and off and adjusting the FOV until I get it as close as possible. Then I render it. I use the presets to save this so I have it set to each of the images I want to render.
Thanks. If you have any ideas on what may be going (or me doing) wrong, please share!