In this tutorial we share our best macro photography tips for learning how to use ISO for close-up subjects. We’ll show you how increasing the ISO will enable you to use a faster shutter speed to avoid camera shake.
The ISO setting on your DSLR controls how sensitive the imaging sensor is to light, and together with the aperture value and shutter speed it determines the exposure of your images.
Most DSLRs have an ISO range of at least 100-6400; the higher the number, the more sensitive to light the sensor becomes.
Increasing the ISO setting enables you to use a faster shutter speed at a given aperture, and there are lots of situations where this is useful.
If you’re shooting handheld, increasing the shutter speed will help to minimise camera shake, particularly in low lighting, and you’ll also need a fast shutter speed to capture fast-moving subjects when shooting sports or wildlife.
Increasing the ISO also enables you to use a narrower aperture setting at a given shutter speed, which you’ll need to do if you’re shooting landscapes handheld and want a broad depth of field to keep everything sharp.
There’s a trade-off for increasing your ISO setting however, and that’s a reduction in image quality. Using a high ISO will introduce image noise, which can make your shots look grainy.
That said, newer DSLRs do a pretty good job of controlling noise at high ISO settings, and you can also reduce noise in Photoshop and other image-editing software.
For this tutorial we’re heading to Somerset’s Mendip hills to shoot damselflies and other insects in the grasses and undergrowth around ponds. Insects are difficult to photograph, as they move very quickly, so we’ll up our ISO in order to get a fast enough shutter speed to capture sharp close-up shots.
How to use ISO in macro photography: steps 1-3
01 Location and kit
For our shoot we found a pond where there were lots of damselflies and other insects; you’ll get more bugs if it’s hot, and better shots if it’s not too windy. We used a Canon EOS 7D and a 150mm macro lens, and shot handheld using natural light; you could use a monopod for additional support, but this will restrict your movements somewhat. Set the lens to autofocus.
02 Set up your DSLR
Set your DSLR to Aperture Priority (Av) mode, and set the aperture to around f/8 – if you need a faster aperture for more light you can open up to f/5.6 and still keep subjects sharp. The shutter speed needs to be fast enough for the focal length, and to counter any subject movement – ideally 1/1000 sec or faster.
03 Balancing ISO and shutter speed
At our 1/1000 sec shutter speed we needed to increase the ISO to 800 to get good exposures. If we have to increase the shutter speed by a stop to get sharp shots we’d need to increase the ISO by a stop to compensate; if we can get away with a slower speed, say 1/500 in our case, we could reduce the ISO to 400. Shoot Raw to maximise image quality at high ISOs.
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