Correct me if I am wrong I am just a noob, but there is a advantage of using an alexa 65 or bigger sensors from a practical pov I think.
For example if you need to shoot a face, how close the lens is to the face is a huge factor to how the image is perceived so with an alexa 65 you can use a longer lens than an s-35 to get closer and get the image, but if you are using an S-35 you would have to use a wider lens which would comparatively start bringing distortion, Or else on a S-35 you would have to move back which starts to bring more of a voyuerstic feel.
