How to install Camera Preview?
Go to Edit > Preferences then to the Add-ons tab. Click Install.
Choose the downloaded zip and click Install Add-on.
After the installation is complete it will show up in the add-on list. Enable the add-on by ticking the checkbox.
How to use Camera Preview?
Once the add-on is enabled, the camera view is previewed directly in the 3D viewport. The preview shows what the active camera sees, rendered live from a dedicated hidden view layer, so you can model and animate while watching the camera framing.
Toggle the preview from the Camera Preview checkbox in the View tab of the sidebar (N-Panel), or from the Viewport Overlays > Guides panel in the viewport header.
The preview header displays the camera name, its focal length and the frame range bound to the camera via timeline markers (or the scene range when no markers are bound).
The preview automatically uses the selected camera object when one is active, otherwise the scene camera. Background images attached to the camera are drawn as reference empties in the viewport.
How to place the preview in the viewport?
In the Camera Preview panel, set Position to Top Left, Top Right, Bottom Left or Bottom Right. The preview automatically avoids the toolbar, header and navigation gizmo areas.
Fine-tune the placement with Offset X and Offset Y.
Set Size to Small, Medium or Large, or choose Custom and enter an exact Width and Height in pixels.
Enable Hide In Camera View to hide the preview while you are inside the camera view, since the full-size camera view is already visible there.
How to hide objects only from the preview?
Right-click an object in the viewport or the Outliner and choose Hide/Unhide in Camera Preview. The object disappears from the preview only, not from the working viewport.
Right-click a collection in the Outliner and choose the same operator to toggle the whole collection in the preview. This is useful for hiding helper geometry, rigs and control shapes while framing a shot.