You don't even need to use HDMI or have a capture card; you can connect the camera with USB and use gphoto2/v4l2loopback to present it to the OS as a video input. With older cameras that have USB2, you will be limited to a lower bandwidth and resolution (200Mbps -> 1024x680), but it still looks fantastic, especially with high-quality lenses and shallow depth of field that enables video codecs to encode the out-of-focus-areas efficiently and concentrate on detail in the focal plane.