Canon EOS 5DS R compared to 5DS
Canon announced two models simultaneously with its 50.6MP full-frame sensor – the EOS 5DS and the EOS 5DS R. The two are identical, except that the effect of the optical low-pass filter is ‘cancelled’ on the 5DS R, which adds a £200 premium to its body-only price (£3,200 vs £3,000). Normally, the optical low-pass filter slightly blurs the image projected by the lens onto the sensor, which helps avoid sampling artefacts such as maze-like aliasing, or false colour patterns due to moiré. The idea is to trade-off ultimate resolution for technically more accurate images.
In practice, the difference between the two cameras’ image quality is subtle. As we would expect, the EOS 5DS R gives slightly crisper images when viewed at the pixel level. But it’s also a bit more prone to giving coloured moiré patterns in finely repeating detail such as fabrics. But Canon’s JPEG processing suppresses this pretty well, and the EOS 5DS isn’t entirely immune from moiré itself. Anything that blurs the image – camera shake, or shooting at a smaller aperture such as f/11 – will in effect mimic the low-pass filter and suppress moiré, too.
So which of the two would I choose? Almost certainly the 5DS R; I’d rather take the extra sharpness, and deal with image artefacts when necessary. The success of the Sony Alpha 7R and Nikon D810, neither of which uses optical low-pass filters, suggests that many other photographers are now comfortable with this approach too.