The perspective camera is a camera type that is similar to cameras in most 3D packages: it creates a perspective image out of a three dimensional scene.
Field of View
The value for field of view indicates the angle between the camera and the leftmost and rightmost visible points in the scene (or the top- and bottommost points, if the image is vertical). The exporter normally gets this information from the selected camera in the scene, but the value can be overridden.
Depth of Field
Depth of field indicates how sharp or blurred objects that are not in focus will appear. In LuxCoreRender this works in the same way as a real camera, by setting the f-stop value. A smaller f-stop creates a more shallow(blurred) depth of field.
Focus distance is the distance between the camera and the focal point, the point in the scene that will be in focus. You can either use an object or a distance to set the focus distance. An easy way to use this feature is to create an Empty object, and use that as focal point. You can use any mesh object but keep in mind that it's the object origin that will mark the focal point, and that is not necessarily on the surface of the object.
The shutteropen and shutterclose entries in the .lxs file are typically used for Motion Blur.
A shift lens is a lens that can move the position of the horizon up or down without introducing perspective distortion in the vertical direction. Amongst others, this can be useful for architectural perspectives where most of the subject is above the horizon.
The unit of measurement for lens shift is the size (either horizontal or vertical, depending which of the two is biggest) of the image. For example, using a horizontal value of 0.5 will result in an image whose left edge is straight in front of the camera.
Camera clipping hides part of the scene, based on the distance to the camera. The two settings, Start and End mark the visible area. Anything outside will be invisible to the camera. The geometry that is hidden by the clipping is still taken into account for the lighting calculations.
The orthographic camera creates an orthographic projection of the scene. This can be used to create straight projections (like a top view or a frontal view) and axonometric projections.
The scale number indicates how many model units fit in image. For example, at a scale of one, one model unit will fit exactly in the width of the image (or the height, in case the height is bigger).
The environment/panorama camera creates a 360 degree image from the current camera position. If the camera is completely horizontal, this results in a panoramic image. Amongst others, this can be used to create high dynamic range environment images for image based lighting.