Why you can trust TechRadar We spend hours testing every product or service we review, so you can be sure you’re buying the best. Find out more about how we test.
Starting up the Pentax Optio RZ18, the camera is ready to shoot nearly instantly, and because of the simple button layout it was very easy to pull the Pentax Optio RZ18 out of your pocket when something cool was happening, turn it on and turn on the Dynamic Range settings - or whatever you needed to set - and still get the shot.
That said, there were a couple of seconds of lag in between taking your shot and being able to take another, during which the LCD display reminds you there's 'Data being recorded' when you try to press the shutter button.
The Pentax Optio RZ18's AF system offers six options: AF Standard, Macro, Super Macro, Pan Focus, Infinity and Manual Focus.
The AF Standard option is what you'll use the vast majority of the time, and we found no real issues with its ability to pick out the most important parts of a scene. Testing it in minimal to cluttered backgrounds, it performs admirably.
In fact, every AF mode performed capably, save for the Manual Focus option, which proved a bit cumbersome to use.
When setting the Manual option, a rectangle appears in the centre of the LCD, with a slider to its right. Using the four-way controller, move the slider up or down until your subject is in focus. It's simple in theory, but movements of the slider are so minute it feels like you are clicking forever.
The Pentax Optio RZ18 has a sensitivity range going from ISO 80 to ISO 6400, and quite handily you can set the Auto ISO range to be limited from 80-100 and in increments of up to 80-1600 to keep noise to a minimum.
This is a nice option, but the problem is, noise and smudging are present even at lower sensitivities.
We noticed some luminance noise and smudging of colours even at some of the lowest sensitivities, and as you move up the scale the problem was compounded.
Noise and mottling of colours begin creeping into images as low as ISO 200, getting worse as you move up the scale.
Now, for sharing photos online and making prints for your photo album, this isn't a problem. You won't notice it. But viewing images at 100% that were taken at ISO 400, you'll see smudging of colours and luminance noise.
That said, for a camera that showed so much noise, even at lower sensitivities, we were surprised by its excellent dynamic range abilities. The Pentax Optio RZ18 features a Dynamic Range setting that enables you to choose one or both of highlight and shadow correction, but even without enabling this function the Pentax Optio RZ18 captures a reasonable amount of detail in high-contrast scenes.
Choosing the Shadow Correction and Highlight Correction enables you to capture a surprising amount of extra detail, as you can see in our example.
For instance, we shot this canal path underneath an overpass, and with the Shadow Correction enabled we were able to capture graffiti on the wall as well as a reasonable exposure on the highlights in the light at the end of the tunnel.
To complement its 18x zoom, the Pentax Optio RZ18 employs CCD-Shift Shake and Dual Shake Reduction systems to help you achieve sharper images when shooting at the telephoto end of the focal range.
Under the CCD-Shift option, the camera applies an equivalent of 2.5 stops of compensation to your image, while the Dual Shake Reduction system boosts the Pentax Optio RZ18's sensitivity up to ISO 6400 (but reducing the resolution to 5 megapixels).
These options do produce a noticeable difference in sharpness, at the expense of a little noise. For the most part, the Pentax Optio RZ18 captured accurate colours, but only with some help from the camera's exposure compensation function.
The Pentax Optio RZ18's exposure compensation range is +2 EV to -2EV in 1/3 stops, and we found we had to generally underexpose by a third - and sometimes two-thirds - of a stop in order to get colours that looked strong and accurate.
Shooting at the base exposure in bright, blue conditions, we repeatedly capture a cyan sky, and in cloudy conditions other strong colours also appear washed out.
The camera's metering system seems perhaps a little biased towards shadow detail at the expense of some of the lighter tones within a scene.
That said, the Pentax Optio RZ18 has a wide range of fun art filters and scene modes that capably compensate for any colour, tone or effect you want to emphasise.
Finally, the Pentax Optio RZ18 records 720p HD video, which is adequate, and matches that provided by most other cameras in this class. Videos are crisp and clear, and our only gripe is that the zoom is locked during recording.
Presumably this is to cut down on noise in your videos, but if you're purchasing a camera in this class for holidays and days out, are you as concerned about a little noise as you are about being able to have that extra flexibility?
