DOF Problem

Over two years, I have used my compact camera to shoot extreme close-up photos of flowers, insects, spiders and other tiny creatures. A lot of people appreciated my pictures as well. However, when I bought a digital SLR and a macro lens last month, I started facing problems. If I am shooting a caterpillar, the head appears sharp but the body turns out of focus. This occurs despite using the same aperture settings on both camera. What am I doing wrong?
Dhruv Malhotra, Lucknow, via e-mail

Since the sensor of a DSLR is much larger, you will need to use a very narrow aperture to get everything in focus, especially if you are shooting close-ups. Photograph/Lynn Cummings

Depth-of-field depends on a number of different parameters, besides the choice of aperture. Sensor size is one characteristic that affects DOF too. The larger the sensor, the more shallow DOF you can obtain, at a particular given aperture. This basically means that even if you shoot at the same focal length and aperture setting, the look of the image can vary depending on the camera used. A DSLR has a far bigger sensor than a compact camera. This is why the DOF you get is much more shallow.

Hence, to get everything sharp in the frame, you will need to use a narrower aperture like f/16 or f/22. This will reduce the amount of light entering the camera, you may need to keep the shutter open for longer, and so, do not forget to carry a tripod.

This article originally appeared in the December 2014 issue of Better Photography.