Color (8.36)
Perhaps you are planning a trip to the Bahamas this year and want to get fantastic shots of the clean blue water and the white sandy beaches. It’d be a pity if you returned from your trip with pictures of reddish beaches and yellowish waters. To see how well the Pentax OptioWP depicts colors, we took several pictures of the industry standard GretagMacbeth color chart and uploaded them into Imatest Imaging Software. The program then compared the original colors of the chart to the colors output by the OptioWP. Below is a modified chart with the OptioWP’s colors depicted on the outer square. The inner square represents the color-corrected version of the camera’s colors (this is what you would see when you uploaded those snorkeling pictures into Photoshop). The inner vertical rectangle is the original color of the GretagMacbeth color chart – or what colors should look like in their ideal tone.

For those of you who think all those squares look like the same color, the information is displayed in a graph below to show exactly how errant or accurate each tone is. The circles on the graph represent the ideal colors from the GretagMacbeth chart. The squares represent the colors produced by the Pentax OptioWP. In a perfect world, you would only see the circles on this chart because the squares would be right underneath them.

This Pentax OptioWP produced decent color tones, earning an overall color score of 8.36. This is pretty good for a compact digital camera, except for the exaggerated red #15 and the blue #13 tones. Almost every camera goes a bit overkill on the red #15, probably to make your Great Aunt Merle’s lipstick even more red in the pictures – and perhaps liven up her skin tone too. The Pentax OptioWP also over-saturates colors slightly, with a 110 percent mean saturation score. This score can also be attributed to the digital camera’s tendency to flush out skin tones more than its inability to render naturalistic colors.

Still Life Scene
Below is a shot of our still life scene captured with the Pentax OptioWP.

Click on the above image to view a full resolution version (CAUTION: the linked file is very large!)

Resolution / Sharpness (3.14)
On your underwater excursion, your little Optio will pack a 1/2.5-inch CCD with 5.19 total megapixels. Of those pixels, only 2560 x 1920 are effective for imaging still pictures. To test exactly how many pixels the WP uses, we took several pictures of the industry standard resolution chart and uploaded them into Imatest Imaging Software. The program counted every last pixel in each image for us. When a camera comes within 70 percent of its advertised effective pixel count, we consider it “good.” When it is within 80 percent, it is perceived as “very good.” A camera that reaches within 90 percent is extremely rare and hailed as “excellent.”

Click on the chart to view the full Res image

The Pentax OptioWP didn’t live up to its 5-megapixel potential, recording only 3.14 megapixels. This is only 64 percent of its largest image size, so it doesn’t even reach the designation of “good.” A disappointing score from a manufacturer with a history in optics and imaging.

Noise Auto ISO (2.28)
Because the Pentax OptioWP is built with mostly automatic features and the point-and-shooter in mind, we had hoped that the noise levels would remain low when the ISO was automatically set by the camera. However, the Optio received a lackluster overall auto ISO noise score of 2.28. This is on the low end of digital cameras, even for compacts. The test was shot in a fixed setting with over 350 Lux of illumination (very bright conditions) and the WP still displayed significant difficulty – producing images comparable to most point-and-shoot cameras at ISO 200.

Noise Manual ISO (4.18)
Pentax does offer ISO choices of 50, 100, 200, and 400 that can be manually set. We tested the noise level at each rating, as can be seen on the graph below. The noise levels are on the vertical axis; the ISO ratings are on the horizontal axis.

To determine the overall manual ISO noise score, we consider the noise level at each ISO rating and plug the data into a regression analysis. The Pentax OptioWP received a score of 4.18, which is better than its automatic score, but still nothing to brag about. So for those snorkeling shots in the Bahamas, be sure to manually set the ISO to get clearer pictures, but between the imager and weak LCD, don’t expect much in the way of clarity.

Low Light (2.0)
If you’re a night owl and tend to take pictures when the sun has retired, pay attention. We tested the OptioWP’s performance in low light by recording four exposures of the color chart at diminishing light levels: 60, 30, 15, and 5 lux. This is much darker than just a cloud cover. 60 lux is about the equivalent of a softly lit room with only two small lamps to illuminate it. The 15 lux test will show how colors and lighting will look if you’re in a room lit only by one 40-watt light bulb. Photographs taken at 15 and 5 lux simply show the limitations of the image sensor by pushing it to the extreme.

We upload the pictures into Imatest Imaging Software and analyze the color error and noise emission. The images are recorded at the WP’s highest ISO rating, ISO 400, and shot in the Program exposure mode. We also manually white balanced the camera before each exposure.

Low Light Tests
60 Lux	30 Lux
15 Lux	5 Lux

Click on the charts to view additional image analysis

So, as you can probably tell, the OptioWP is pretty weak in low light situations. This may present a problem underwater, though the camera’s depth limitations will work in the user’s advantage in that regard. At 60 Lux, the camera performed reasonably — exposing images with some definition in form and distinction in color, though focusing issues could not be avoided. The manual focus method proved difficult in dim conditions as well. When the light levels dipped below 60 Lux, the OptioWP was rendered virtually useless. Colors became muddy, losing all vibrancy and tonality. Noise also increased substantially — an unavoidable problem in a camera that displayed difficulty controlling stray noise even in daylight. I would not recommend using this camera at night, unless you’re partial to flash photography — this may put a damper on those coral explorations.

Speed / Timing
Startup to First Shot (7.45)
This digital camera takes 2.55 seconds to start up and take its first shot, which is about average for a compact in this price range. Just be sure to have the camera on long before any important action is about to happen.

Shot to shot (8.89)
There are two burst modes on the camera, Continuous and High Speed Continuous. The first mode shoots at any resolution setting, but is hardly a burst mode with about a second and a half between shots at the highest resolution. The high speed mode can only shoot at 1280 x 960-pixel resolution, which will be good enough for small prints. It shoots at a much faster 3 fps rate. The camera took seven pictures with about 0.3 seconds between shots, then took an 11-second rest before taking its next burst of pictures.

Shutter to shot (8.08)
The Pentax OptioWP takes a leisurely 0.46 seconds to take a picture from the time you press the shutter release button. This is quite slow and may cause frustration for the photographer who notices a few blinked eyes have appeared on the subjects. Or worse, that endangered gulf sturgeon fish will swim away before the WP can capture it – and no one will believe that you saw it.