How to Display the Live View Preview on an HDMI Screen
You can connect your Nikon D7100 camera to an HDMI (High-Definition Multimedia Interface) device to see the Live View output on that screen. This feature is often used by studio photographers who want a larger view of their subject than the camera monitor provides.
A few issues arise when you take advantage of this option:
You must buy an HDMI type-C mini-pin cable to connect the camera to the TV. The cable isn't provided with the camera.
The on-screen shooting data appears differently. Specifically, camera settings appear along the sides of the live image instead of atop it. Also, during movie recording, you can't display the virtual horizon tool or show or hide monitor data using the Info button. Nor does the audio volume meter appear during movie recording.
You may need to set the Output Resolution option to a setting other than Auto. When you connect the camera to an HDTV playback, the camera automatically adjusts the HDMI output to your HD display. But when the Live View switch is set to Movie mode, the signal is output according to the selected movie Frame Rate/Frame Size setting.
If your TV doesn’t support your chosen movie settings, the answer may lie in the HDMI option on the Setup menu. After selecting that option, try changing the Output Resolution to a setting other than Auto. Your movies may be output to the HD monitor at a frame size smaller than the one you set for the movie recording, however.
During movie playback, the camera monitor shuts off at some Frame Size/Frame Rate settings. You can see the movie only on the HD device when you use a frame size of 1920 x 1080 and a frame rate of 60i or 50i or a frame size of 1280 x 720 together with a frame rate of 60p or 50p.
When you connect the camera to an HDMI-CEC device, set the Device Control option to Off. That's one of the two options available for the HDMI setting on the Setup menu. You can’t take pictures or shoot movies when the Device Control option is set to On, as it is by default.
In case you're wondering, CEC stands for Consumer Electronics Control and is a specification that enables you to use your HDMI TV's remote control to operate other devices. For example, if you turn on the Device Control option, you can use the remote to perform the functions of the Multi Selector and OK button during picture playback. The feature just isn't compatible with picture taking and movie recording.