Scientific Photography and Applied Imaging

28 Telephotography

28.1 Introduction

Telephotography is taken to mean the use of lenses or optical systems of very long focal length or narrow FOV relative to the recording format, principally to produce images of usable size from distant subjects. Such systems, especially for extreme telephotography, find applications in aerial and astronomical work as well as for terrestrial uses such as surveillance, animal behavioural studies and sports events. Other applications include range instrumentation and long range oblique photography (LOROP).

Note that the EFL (f) determines magnification (m). Given that m = v/u, as u ≥200f or u approximates infinity then v ≈ f. So m ≈ f/u, i.e. image size is directly proportional to focal length; see Figure 28.1 ...