The telescope can increase or decrease the field of view (FOV) of the camera. When the FOV is reduced, the camera will zoom in to see distant objects better; when the FOV is increased, the camera zooms out to view its local surroundings. To change the FOV, hold the [Shift] key and Left mouse button ([LMB]) and move the mouse forward and backward, or press the [PgUp] and [PgDn] keys. To return to the standard field of view (45°) press the [Middle mouse button] or the [Home] key. Pressing the same button again will return to the previous field-of-view.
Information about the current field-of-view is displayed at the lower right-side corner of the screen: «FOV 45°00'00"00». This is the angle between the upper and lower sides of the screen in full-screen mode, or between the upper and lower sides of the window in windowed mode. To calculate the FOV angle at which an image rendered by SpaceEngine appears as it would look to the to the eye if your monitor were a spaceship window, (such as seeimg the real apparent angular size of the Sun and Moon as seen from Earth), follow this formula:
FOV = 2 arctan(h/d/2),
where h is the height of the screen in cm, and d is the distance from the naked eye to the center of the screen in cm. This angle is usually around 10°-20°. It can be adjusted in the user configuration file config/user.cfg under ZoomFOV parameter. Thereafter, clicking the [Middle mouse button] or [Home] key will apply this FOV value by default.
The maximum FOV is 120°, and the minimum is 0.01" (this can be adjusted in user.cfg). Decreasing the field of view automatically increases the limiting apparent magnitude of all objects, as if seen through a telescope with a large aperture.