Technique IBIS VS ISO
IBIS vs ISO
Both are useful in low light, but they do not give the same results. Rod Lawton explains all
We all want sharp shots, but this becomes especially challenging in low light conditions and night photography where the camera will normally increase the exposure time with a slower shutter speed – but this does of course introduce the risk of camera shake.
The traditional solution is to increase the camera’s ISO setting, or sensitivity. This will make it possible to use faster shutter speeds to combat or eliminate any camera shake. But an increasing number of cameras offer an alternative – in-body stabilisation, or ‘IBIS’. This can help to keep your photographs sharp at slower than normal shutter speeds, so that you may not need to increase the ISO setting.
What is ISO?
ISO is the sensitivity setting of the camera sensor. You can increase the ISO value to make the sensor more sensitive to light, which allows for faster shutter speeds in low light so that there’s less risk of camera shake. However, increasing the ISO setting also progressively reduces the image quality, introducing visible noise. This is why photographers generally like to avoid high ISO settings, though usually it’s an acceptable compromise in order to get a sharp shot. With modern cameras you can generally push the ISO up to 6400 and beyond before you see serious image deterioration, and this is one of the factors we test in our camera reviews.
What is IBIS?
‘IBIS’ stands for ‘in-body image stabilisation’. It’s a mechanism that moves the sensor to compensate for any movement during the exposure, which is detected by tiny gyroscopic sensors in the camera. This can give you sharp shots at shutter speeds where you would normally expect camera shake and blur. The effectiveness of an IBIS system is usually measured in EV values, or ‘stops’, so that a system that offers 5EV compensation could let you get sharp shots at shutter speeds 5 stops slower than the normal ‘safe’ speed.
In-body stabilisation works well for mirrorless cameras, but in-lens stabilisation works better for DSLRs because it stabilises the image in the viewfinder too.
‘Safe’ shutter speeds explained
There is a rule of thumb used by photographers to work out the slowest shutter speed it’s safe to use without getting camera shake. You take the effective focal length of your lens (allowing for the different crop factors of different cameras) and then divide it into 1 to get the minimum shutter speed. S
