Insect Macro Photography - from Good to Great!

摘要

The advent of digital photography has enthused many an entomologist to capture his or her favourite bug up close and personal. To those that have tried, insect portraits are far more challenging than those of your family. This has to do with the closefocusing distances required which brings with it very narrow distances that are in crisp, sharp focus, referred to as depth of field. Indeed, as one gets closer to the subject this decreases the focal length and subsequently the depth of field gets evenshallower. So what does the insect photographer do to get as much of the bug in focus as possible? Well depth of field can be controlled by reducing the lens aperture such that the light travels through a smaller hole (think pin hole camera). This consequently then reduces the amount of light reaching the light sensor (be it film or a digital sensor) so to achieve a correct exposure you have to either have a longer shutter speed (which for frisky insects is not an option unless your into creative blur!) or provide more light on the subject such as using a flash gun which is a common solution. So you have your flash gun and small aperture selected and ready to go. If only it was that simple! By stopping your lens down to its minimum aperture you then find you degrade the quality of your image due to diffraction, so actually a lens is at its most sharpest generally in its mid F stop range. For example, a macro lens will typically provide F stops of F2.8 (lens wide open and lets in plenty of light) to F22 (very small hole). However it will give the sharpest image somewhere between F8 and Fll. So taking these settings will give you reasonable insect mug shots which if the insect is perpendicularly flat to the camera will look good, for example side on.The problem of small depths of field will persist when trying to image across a large distance, for example head on looking down the body or multiple insects at different distances the lens. For a complete guide to insect macro photography have a look athttp://www.insectography.com/in dex.html.