Field-of-view may be very wide, wide, medium, or narrow. It is easiest pictures as a cone emanating borescope tip, so that anything within the cone is visible. The field-of-view of the Hawkeye Slim borescope is approximately 37°.
Field-of-View should be dictated by the distance from the distal end of the borescope to the subject, for your application. The wider the field the lower the magnification, and vice versa. If you have plenty of space to move inside the cavity, but want to see both detailed close-ups and big picture views you might choose a 67° moderate wide angle. If the space is more confined but you still need to see most of it at one time, try a 90° extreme wide angle. On the other hand, if you can't get close enough to show the detail you need, a 30° telephoto might be required.