Olympus C-50 Zoom Review: 14. Compared to...: Digital Photography Review

Compared to... (contd.)

Here we will use our standard color and resolution charts to compare C-50 Zoom to the Pentax Optio 550, 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.


Olympus C-50 Zoom	Pentax Optio 550

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	Olympus C-50 Zoom	Pentax Optio 550	Canon PowerShot S50	Nikon Coolpix 5000
Black	37,31,40	26,25,25	33,34,35	19,20,19
Middle Gray	105,105,116	95,92,93	96,100,103	91,91,91
White	218,221,227	217,211,210	208,210,211	209,209,205
Magenta	201,10,127	210,18,99	199,44,121	219,37,93
Red	199,9,48	196,14,26	197,37,46	207,26,23
Yellow	215,204,20	204,196,45	203,193,23	212,189,47
Green	18,142,77	19,149,74	9,136,72	0,130,68
Cyan	8,149,202	23,178,227	6,144,214	1,153,200
Blue	53,35,121	45,28,106	29,41,109	33,44,98

The C-50 Zoom's white balance did seem to consistently produce a cooler (more blue) white balance than the other cameras. This can be seen by the high value of the blue channel above (most noticeable in the black, gray and white patches). The C-50 Zoom's color balance is probably closest to Canon's PowerShot S50.

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 1/100^th 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.

Olympus C-50 Zoom (2,152 KB)

Pentax Optio 550 (2,254 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.
Olympus C-50 Zoom	Horizontal LPH	* 1425	* 1650
	Vertical LPH	* 1300	* 1650
	5° Diagonal LPH	+ 1000	n/a
Pentax Optio 550	Horizontal LPH	1350	1500
	Vertical LPH	1250	1450
	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 C-50 Zoom surprised us in the resolution test because here it produced as much resolution as the Canon PowerShot S50 and more than the Pentax Optio 550. This surprise due to its performance on the previous page, our side-by-side comparison. We can only conclude that the C-50 Zoom lost some of its ability to resolve detail in that test because of increased image noise. Overall the C-50 Zoom produced higher resolution than we would expect from a compact five megapixel digital camera (although it's worth noting the moiré at the limit).

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