Compared to... (contd.)

Here we will use our standard color and resolution charts to compare Optio 550 to the Olympus C-50 Zoom, Canon PowerShot S50 and Nikon Coolpix 5000.

Colour Chart Comparison

Colour charts are shot in daylight, Auto White Balance, EV compensation +0.3 (all cameras), measured light ~10 EV. This test is also dependent on the accuracy of the camera's auto white balance, the colour charts are shot in daylight but some camera's white balance is better than others. All cameras are given 20 seconds to "settle" before the shot is taken.

Pentax Optio 550 Olympus C-50 Zoom
Canon PowerShot S50 Nikon Coolpix 5000

In the table below we're only measuring colour. The RGB values were measured from a VGA reduced image (to average colors, remove noise and eliminate JPEG artifacts) using the Eyedropper tool in Photoshop with a 5 by 5 Average Sample Size.

Patch Pentax
Optio 550
C-50 Zoom
PowerShot S50

Coolpix 5000

Black 26,25,25 37,31,40 33,34,35 19,20,19
Middle Gray 95,92,93 105,105,116 96,100,103 91,91,91
White 217,211,210 218,221,227 208,210,211 209,209,205
Magenta 210,18,99 201,10,127 199,44,121 219,37,93
Red 196,14,26 199,9,48 197,37,46 207,26,23
Yellow 204,196,45 215,204,20 203,193,23 212,189,47
Green 19,149,74 18,142,77 9,136,72 0,130,68
Cyan 23,178,227 8,149,202 6,144,214 1,153,200
Blue 45,28,106 53,35,121 29,41,109 33,44,98

The Optio 550 produced pleasing, balanced results with fairly good saturation in each of the primary colors. Automatic white balance delivered good results with an almost perfect mid-gray. Compared to the other five megapixel digital cameras the Optio 550's colors were slightly 'lighter' but had similar saturation.

Resolution Comparison

Shots here are of the PIMA/ISO 12233 standard resolution test chart (more of which are available in our comparison database). This resolution chart allows us to measure the actual performance of the lens and sensor system. It measures the ability of the camera to resolve lines at gradually higher resolutions and enables us to provide a definitive value for comparison purposes. Values on the chart are 1/100th lines per picture height. So a value of 8 equates to 800 lines per picture height.

Studio light, cameras set to auto, all settings factory default. Exposure compensation +0.7 EV for all cameras (to compensate for the white background). Click on the camera name below the crops to download the full resolution chart (large JPEG's).

Horizontal resolution Vertical resolution 5 degree diagonal res.
Pentax Optio 550 (2,254 KB)
Olympus C-50 Zoom (2,152 KB)
Canon PowerShot S50 (2,011 KB)
Nikon Coolpix 5000 (1,609 KB)

Measurable findings (three measurements taken for each camera)

Camera Measurement Absolute Res. Extinction Res.
Pentax Optio 550 Horizontal LPH 1350  1500 
Vertical LPH 1250  1450 
5° Diagonal LPH + 1000  n/a 
Olympus C-50 Zoom Horizontal LPH * 1425  * 1650 
Vertical LPH * 1300  * 1650 
5° Diagonal LPH + 1000  n/a 
Canon PowerShot S50 Horizontal LPH 1425  1650 
Vertical LPH 1300  1600 
5° Diagonal LPH # + 1000  n/a 
Nikon Coolpix 5000 Horizontal LPH * 1350  * 1500 
Vertical LPH * 1200  1500 
5° Diagonal LPH + 1000  n/a 

* Moiré is visible, + Chart maximum, # Jagged diagonals

Definition of terms

LPH Lines per Picture Height (to allow for different aspect ratios the measurement is the same for horizontal and Vertical)
5° Diagonal Lines set at 5° diagonal
Absolute Resolution Still defined detail (below Nyquist frequency*)
Extinction Resolution Detail beyond camera's definition (becomes a solid gray alias)
n/a Not Available (above the capability of the test chart)
n/v Not Visible (not visible on test results)
* Nyquist frequency defined as the highest spatial frequency where the CCD can still faithfully record
image detail. Beyond the Nyquist frequency aliasing occurs.

The Optio 550 does reasonably well (average five megapixel performance). It appears to be at least a match for Nikon's Coolpix 5000, surprisingly it didn't produce as much detail as the Olympus C-50 Zoom which it did beat in our side-by-side comparison on the previous page (probably a factor of the C-50 Zoom's noise level in that shot). It's a fairly good performance if you consider the Optio 550's five times optical zoom.