Setting Up Crop Nodes

Once your Write nodes are connected, if you want one of your renders to be in a different aspect ratio than your scene's, you can use the Crop node. For example, if you want a scene with an aspect ratio of 16:9 to produce a render in 4:3, you can use a Crop node to crop out the image on the left and right edges of the camera frame.

You can use a Scale-Ouput node in conjunction with a Crop node to produce a render that is in a different resolution and aspect ratio than your scene's. For example, if you want a scene in HD 1080p to render in NTSC, you can use the Scale-Output node to scale down the image to 960 x 540 pixels, which matches the NTSC resolution height, but has a greater resolution width to preserve the aspect ratio of HD 1080p. Then, you can use a Crop node to crop the image to 720 x 540 pixels, cropping out the image in the left and right edges to make it fit an NTSC screen.