It has different behavior in DSLR and CCD/CMOS modes.
Canon EOS mode
In EOS mode LiveView is a feature provided by the camera to get real time images. It is affected by settings ISO and Exposure that can be controlled from Camera Tab (DSLR Mode). By default APT will use for LiveView the highest ISO and Exposure settings in order to provide high sensitivity suitable for deep space objects. This feature is named LiveView Automation and can be disabled/enabled from Main Settings Tab.
Using "Zoom +" and "Zoom -" you can increase/decrease the LiveView zoom level to 5x (or 10x if it is clicked two times). For most EOS cameras Zoom x5 is very close to the representation "1:1" - "one pixel from the image, represents one sensor pixel". It is valuable feature for planetary astro-photography.
Troubleshoot: If the Zoom+ is not working, then go to the camera menu and disable the Face Detection feature (for the newer models use "FlexiZone AF" not "Live AF"). It is not compatible with LiveView zoom.
Tips & Tricks:To place the zoom window in the center of the image, use Shift+Double click.
Tips & Tricks:When Zoom x5 or x10 is enabled APT shows small cross to mark the exact center of the camera sensor. It is useful when precise star alignment is needed.
Nikon mode
In Nikon mode LiveView is a feature provided by the camera to get real time images. It not is affected by settings ISO and Exposure that can be controlled from Camera Tab (DSLR Mode). For Nikon cameras you can disable the feature LiveView Automation from Main Settings Tab.
Using "Zoom +" and "Zoom -" you can increase/decrease the LiveView zoom level to from 0% to 100%. For most Nikon Zoom 100% is the representation "1:1" - "one pixel from the image, represents one sensor pixel". However the poor quality of the LiveView stream doesn't allow it usage for planetary astro-photography.
Tips & Tricks:To place the zoom window in the center of the image, use Shift+Double click.
In CCD/CMOS mode
In CCD/CMOS mode LiveView takes endless series of images that are not stored on the hard disk. The Binning, Gain and Exposure settings can be controlled from the Camera Tab (CCD/CMOS mode). If the feature LiveView Automation is enabled APT will select automatically the biggest supported Binning settings to maximize the sensitivity. This feature can be disabled/enabled from Main Settings Tab.
The CCD/CMOS cameras have no hardware supported Zoom. In order to make a software zoom you can use Tools->Magnifier feature.
The LiveView works in this mode for the cameras connected via ASCOM driver, SBIG, INDIGO/INDI. Sometimes is also referred as "Images LiveView"
In native ZWO mode
When a native connection is made to a ZWO camera (coming soon for Altair Astro), the following dialogue box will be opened on LiveView activation.
It gives possibility to enable "Video LiveView" which give much faster transfer , shorter exposures and possibility to use automatic exposure duration and gain value (depends on the camera model). Un-checking the option "Video LiveView" switches to "Images LiveView" where the exposure parameters are controlled from the Camera Tab (CCD/CMOS mode)
