Noise, resolution and sensitivity
These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using the Sigma 105mm f/2.8 Macro lens set to f/8. We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting
All the upper-entry-level and enthusiast-level Canon DSLRs feature an 18-million-pixel CMOS sensor, so it is no surprise that the 650D is a match for resolved detail at its base ISO 100 setting. At this setting and in raw capture, the camera reaches 28 on our resolution chart, while in JPEG capture the camera resolves up to the 26 marker.
This level of performance, however, does not equal the resolved detail of the 24-million-pixel CMOS sensors that have started to appear on the market. In real terms, the maximum 5184×3456-pixel output produces 17.3×11.5in prints when the file is sized to 300ppi resolution, which is sufficient for most photographers.
It is at its higher ISO settings that the 650D offers a marginal improvement over the 600D. Not only is there a single-stop advantage at ISO 12,800, but the camera’s ability to control noise at like-for-like settings above ISO 800 is greater.
Both cameras are capable of producing a good level of detail even up to ISO 6400, but images of the resolution chart from the 650D show more discernible detail.
In real-world images, detail looks clean even up to ISO 1600. Beyond this setting, luminance noise becomes less ‘tidy’ and detail is compromised. Chroma noise in raw files is evident at ISO 3200 and higher, which is corrected efficiently in JPEG files (as well as chromatic aberrations that occurred when using the 85mm f/1.8 lens). Applying noise reduction post-capture allows sharper and more detailed images rather than using the control in-camera with JPEGs.
In this image taken with the Canon 85mm f/1.8 lens, fringing around the harmonica is obvious in the unedited raw file, but the JPEG file does a good job of dealing with the lens distortion
