SOME of the special requirements for illumination in photography of the anterior segment of the eye appear to be met more satisfactorily by a recently developed type of light source than by methods previously employed. For several reasons, in ocular photography it is expedient to have the camera relatively close to the eye. But the different distances of various structures of the eye, especially of its adnexa, from the camera make it necessary to use rather small lens apertures to obtain sharp definition. The small aperture of the diaphragm necessitates high levels of illumination for adequate exposure of the film.
With a lens aperture of f/2.8 a segment of the eye 5 mm. in depth is in fair focus, while with an aperture of f/16 a segment 20 mm. in depth is in comparable focus and the sharpness in the midrange is, of course, significantly improved. Because of the sensitivity
TROTTER RR, GRANT WM. ELECTRONIC FLASH (GAS DISCHARGE) TUBE IN PHOTOGRAPHY OF THE ANTERIOR SEGMENT OF THE EYE. Arch Ophthalmol. 1948;40(5):493-496. doi:10.1001/archopht.1948.00900030506002