Photography News 08

Camera review

ISO performance

SONYA77

NIKOND7100

The other top-end flagship model in our group, the Sony A77, didn’t perform so well – the semi-translucent mirror necessarily causes some light loss, and this becomes a real issue in low light. From ISO 1600 upwards, noise starts to degrade image quality significantly, and performance is at least two stops behind the Nikon D7100. Although a mid-level camera, the Nikon D5300 wasn’t far behind the D7100, and image quality again held out extremely well until at least ISO 3200. Overall, it was perhaps just one third of a stop behind the D7100, and colour accuracy was not maintained quite so well at the higher sensitivities. Also a mid-level camera, the Canon EOS 70D put in a good performance too and wasn’t far behind the D5300, but noise just had a little more impact on image quality at ISO 3200 and 6400. At the entry level, the Sony A58 and Canon EOS 700D were closely matched, although the Sony just had the edge at mid-level sensitivities – at ISO 1600, noise levels aren’t lower per se, but contrast is better and more detail remains. From ISO 3200 upwards, the Sony starts to suffer a little more, and the Canon takes the lead. Perhaps most surprisingly, the Sony A58 put in a slightly better performance than the A77, even though it’s well below it in the Sony line-up – that’s most likely down to the fact that it’s a much more recent camera.

We tested the APS-C DSLRs in low light to see how increasing ISO sensitivity impacts on image quality in each case. The same twilight scene was photographed with all cameras as ISO sensitivity was progressively increased. In all cases, aperture was kept constant at f/5.6 and the lens was set to a focal length of 24mm. The cameras were mounted on a tripod and triggered with the self-timer function. All noise reduction was turned off in-camera, and Raw images were converted in Adobe Lightroom 5 with luminance and colour noise reduction turned off. Across the board, noise started to creep in at ISO 800, although the impact on image quality at this level was generally minimal. Above this, performance diverged. The best was the Nikon D7100, which produced perfectly useable images up to ISO 3200. Above this, noise increased more noticeably, but performance stayed ahead of the field.

ISO 100

ISO 1600

ISO 3200

ISO 12,800

CANON EOS 70D

NIKOND5300

SONYA58

CANON EOS 700D

ISO 100

ISO 1600

ISO 3200

ISO 12,800

Photography News | Issue 8