Live View (seeing the photo on the back of the camera instead of through the viewfinder) is not generally recommended. Use the viewfinder!
Except in a few special circumstances.
Namely, you would use Live View when you need accurate manual focusing. This is often the case when shooting macro, or product, or night pictures, when the camera’s autofocus either will not work well, or is not accurate enough.
On many cameras, like on my Canon bodies, you can:
- Set focus to “manual” (slide on the lens goes to “M”);
- Put the camera on a tripod;
- Activate Live View;
- Zoom in on the preview (press the “+” loupe symbol, or just the loupe symbol on many Nikon bodies). Repeatedly: on the Canons, when you press it twice, the preview shows (10x” (i.e. 10x magnification);
- Now focus accurately by hand;
- Now turn off live view.
You are now ready to shoot. Ensure that your subject and camera do not move, and that you do not zoom in or out after focusing (most lenses will lose focus if you do), and especially, that you do not accidentally move the focus ring.
I am writing this as I prefer to do some night sky shots in the next few days, provided I can find a clear sky without too much light pollution.
By the way, my favourite lens for night sky shots is my 35mm f/1.4, which offers pretty much the best combination of:
- Large real aperture diameter (means more light gathering) and
- Wider angle (means longer times are possible without creating star trails. To understand why, imagine a telescope: the longer it is, the more the stars will move).
14 seconds at 1600 ISO at f/1.4 should do it. And at that aperture, accurate focusing is essential—which brings us back to where we started: manual focus using Live View.