Aperture and shutter speed selection play a huge part in photography – now add ISO to the list
ISO 400
1.2 secs
LOW ISO/SLOW SHUTTER SPEED
West Burton Falls in the Yorkshire Dales was in full flow and to achieve a milky water result, it required a slow shutter speed. With the camera and 70-200mm lens on a tripod, I took my first test shot at a speed of 1.2 secs at f/22 and ISO 400 and, although that produced a nice blur in the flowing water, I decided to go even slower. The first consideration was the tree branches, which I preferred not to blur. Thankfully, it was a still day so there was no problem here. To get a longer shutter, I dropped down from ISO 400 to ISO 100 to give an extra two f/stops of blur and the final exposure was 5 secs at f/22.
ISO 400
1/800 sec
MEDIUM ISO/FAST SHUTTER
Modern digital cameras are so good that standardising your photography on ISO 400 or even 800 is no problem and the results will be first-rate with minimal noise. Being able to use such a high ISO speed allows plenty of options when it comes to aperture and shutter choice. This is LMS 46100 Royal Scot, photographed at Appleby station. It was a grey, cloudy day but using ISO 400 on a Canon EOS R8, a 24MP full-frame camera meant I could try 1/800 sec at f/8. With a 35mm focal length, f/8 gave plenty of depth of field, so the train is fully sharp while 1/800 sec meant there was no risk of camera shake, as I was moving and shooting quickly in the crowd to get a people-free shot.
ISO 25,600
1/60 sec
FAST ISO/FAST SHUTTER
Street photography often means having to tap into your camera’s high ISO skills, especially if you don’t own a fast aperture lens. For this shot, which was taken on London’s Tower Bridge, a Nikon D4 camera was fitted with a 24-120mm f/4 zoom. A few minutes earlier, I had been taking some skyline shots at ISO 100 with the camera mounted on a tripod, but seeing this photo opportunity unfolding ahead of me, I quickly took the camera off the tripod and changed the ISO to 25,600, the camera’s top native speed. With the 24-120mm wide open at f/4 that ISO enabled me to take a handheld photo at 1/60 sec. The raw image here has not been treated in any denoising software.
ISO skills
Most cameras have a noise reduction (NR) feature to minimise the grainy look of high I
