How to render over camera border or overscan?

Question

i want to render over camera border, i don't know what it's called in Blender, but in Nuke it's called OVERSCAN which you can render outside the camera border (or bigger than the actual resolution) which then saved as .exr (exr can save area outside your visible resolution). Of course i'm not allowed to change the focal length. The camera tracking was done in Nuke and sent to Blender to build the 3d and i need to send the render files back to Nuke with exact focal length except i need to render beyond the border (overscan) because in Nuke it will be added lens distortion which will shrink the images (render files) a bit. If i don't do overscan , there will be a black around the images after applying lens distortion in Nuke.

So how can i do OVERSCAN in Blender ?

Answer 1

There is currently no builtin way to correctly setup an overscan. However you can simply use the workaround Andrew Price mention in his twitter feed from 2015.

In the render dimensions set to 105%. Then with the camera selected, go to focal length, click edit, add *0.95 to end of whatever is current.

To add 20% to the image:

1. Go to the render dimensions and enter 120% under the Resolution section.
   
2. Then click into the focal length field of the camera and divide the current focal length by 1.2
   

This obviously won't produce a true overscan, like an .exr image supports. You'll have to add a Reformat node (centered) in Nuke manually.