Robert W. Hegner, Bird-Lore: Volume I No. 2 — Photographing a Bluebird (1899)
“ I disturbed the female several times before she gained the desired position at the nest-opening; but, finally, the snap of the shutter helped bring to life one of my best bird-pictures. A knowledge of the bird's nesting habits is a prime requisite in avian photography. Much patience is needed, as failures are very numerous. A camera which may be focussed to within two or three feet is an absolute necessity in order to make the picture large enough. ”
