Nikon Coolpix S9100 review

The video mode hits the spot with 1080p capture in AVC format, complete with fully functional optical zoom and autofocus (the latter is initially fixed while recording but there’s a menu option to enable continuous autofocus). Clips last for up to 29 minutes, with a countdown rather than elapsed time readout so it’s clear how much time is left. Picture and sound quality were both excellent, and lens motor noise barely registered on the soundtrack.

Handheld telephoto videos were quite wobbly, though, with the electronic stabilisation proving no match for the powerful optical stabilisation used for photo capture. The modest 15Mbit/s bit rate resulted in blocky artefacts in fast-moving scenes, but on balance we prefer this to the much higher bit rate used in some Canon cameras, which in turn limits recordings to around 15 minutes.

We stated earlier that back-illuminated sensors are more sensitive than conventional designs, but the reality is a little more complicated. The difference is in the way the sensor’s internal wiring is laid out, which means that more light reaches the individual pixel photosites rather than hitting the wiring and being wasted. However, there’s only so much light that can be measured for each pixel before it reaches saturation. As a result, back-illuminated sensors typically produce significantly less noise than conventional sensors for a given ISO speed, but their minimum ISO speed is usually higher: in this case, 160, whereas 80 or 100 is the norm.

Image stabilisation was effective at high zoom ratios – click to enlarge

What that means in practice is that, when there’s plenty of light, there’s little benefit to this type of sensor. The S9100’s photos taken in bright light at ISO 160 were a little less grainy and more natural-looking than shots taken with the 14-megapixel Panasonic DMC-TZ20, but the difference wasn’t huge. However, when low light or telephoto zoom settings demanded higher sensitivities of ISO 400 and up, the S9100 exhibited a vast improvement over the TZ20 and its ilk. Whereas the TZ20 relied on detail-smearing noise reduction to make these shots appear vaguely presentable, the S9100 retained plenty of detail while maintaining reasonably smooth colours.

The back-illuminated sensor produced far less noise at higher ISO settings than normal – click to enlarge

The Auto mode usually chose a sensible ISO speed for each shot, but it made a few bad calls that resulted in blur-inducing slow shutter speeds. None of the scene modes seemed particularly keen to venture up to ISO 1600, so we sometimes had to set the ISO speed manually for best results. We also found that the autofocus could be a little unreliable when trying to lock onto moving subjects. It’s a common problem for ultra-zoom cameras because focus is more selective at telephoto settings, but here it was more common than usual.