The Panasonic GH5 has an internal waveform and vectorscope, zebras, and you can check focus with focus peaking. Despite all this, it still makes sense to have an external monitor tacked on. Sareesh Sudhakaran from Wolfcrow suggests ten possible reasons why you still may need to use the external monitor when shooting with the GH5, and the principle also works with other cameras like Sony a7s II, Canon 5D Mark IV and so on.
https://www.youtube.com/watch?v=P6tsZE6ixNo
1. Frame markers
The GH5 doesn’t have standard or custom frame guides like 1.85:1 or 2:39:1. If you need these options, you need an external monitor.
2. De-squeeze
It’s said that Panasonic will release a firmware update that allows de-squeezing anamorphic images in-camera, but it’s not there yet. The external monitor will help you frame exactly to your final look, without cropping off the sides, as long as it has a combination of de-squeeze and frame guides.
3. Easy flicker detection
With a large 7” screen, it’s much easier to detect the flicker than on a tiny camera’s screen. The GH5 has a flicker correction option, but the fact is that you can’t correct what you can’t see.
4. Easy detection of motion effects
If you change shutter speeds, you get different kinds of motion effects. You won’t go if you’ve gone too far, because it’s hard to study motion on the camera’s LCD. Just like with flicker, a larger monitor will help you see these effects better.
5. Custom profiles
Camera screens still don’t produce very accurate colors. In order to accurately set profile colors, you need a calibrated professional grade monitor.
6. More visible in bright light
The screen of a GH5 is barely visible in bright outdoor conditions. Because of this, you can use an external monitor with a hood. It will sit at a nice height and allow you to see well what you’re shooting.
7. Maneuverability
You can attach the external monitor with a magic arm and swivel it into any position, or detach it and hold it in your hands. The flip screen of the GH5 is great as well, but the external screen gives you more options. Plus, the camera’s monitor is somewhat hindered by the HDMI cable if you’re using an external monitor.
8. Others can see what you’re shooting
If you have a crew that depends on the live image to do their work well, you need an external monitor. Focus pullers, hair and makeup artists, the director, anyone who has paid an admission to watch – they can all benefit from the external monitor.
9. Use of false color
With an external monitor, you can use false color if you find it useful and intuitive.
10. You can power external monitors separately
GH5 has a great battery life, but other cameras like Sony a7s II don’t. If you can power the monitor separately, you can save the camera some battery life. Sareesh mentions some other reasons for using external monitors for shooting, such as easier focus assistance, looping through the video, or even converting from HDMI to SDI. Professional monitors have tactile buttons, and they last a longer time than flip screens of the camera. Now, of course, despite all the advantages, the price can be a bit of an issue. But if you shoot professionally, I guess it pays off and you will find it useful. [10 Reasons why we need External Monitors|Wolfcrow]