Sony DSC-S85 Review: Digital Photography Review

Compared to... (contd.)

Colour Chart Comparison

Now we can compare the Sony DSC-S85 to a few of other cameras. I've deliberately added Olympus's E-10 to the mix simply because it's the only other native 4 megapixel digital camera currently available, obviously it's not in the same price range or market sector as the S85. Using samples from our test archives, we will now compare its image quality to the Olympus E-10, Sony DCS-S75, Nikon Coolpix 995 and Canon PowerShot G1.

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.


Sony DSC-S85	Olympus E-10	Sony DSC-S75

Nikon Coolpix 995	Canon PowerShot G1

The DSC-S85's colour reproduction is accurate and vivid, notably less saturated than the DSC-S75 which some people would consider to be too 'bright' and a little over saturated. The S85's colours are a little easier to live with and ensure that coloured highlights won't get blown out so easily.

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

Patch	Sony DSC-S85	Olympus E-10	Sony DSC-S75	Nikon Coolpix 995	Canon PowerShot G1
Black	17,17,19	24,22,25	23,22,24	25,25,23	34,32,34
Black
Middle Gray	76,81,79	82,87,96	90,94,95	103,103,102	97,96,102
Middle Gray
White	188,189,189	182,191,200	193,195,194	215,215,211	214,208,208
White
Magenta	170,12,124	169,25,95	199,7,130	207,38,117	204,41,121
Magenta
Red	176,0,40	166,29,42	205,0,26	197,31,50	189,31,53
Red
Yellow	181,180,14	179,180,45	185,189,17	216,188,36	205,193,59
Yellow
Green	24,131,27	9,110,63	34,138,34	8,136,61	26,149,73
Green
Cyan	23,158,175	7,119,184	42,153,200	52,164,196	58,180,230
Cyan
Blue	23,31,112	34,25,92	31,24,152	41,33,84	55,49,117
Blue

Probably most immediately apparent is the less saturated look of the S85 colour patches compared the S75. This isn't necessarily a bad thing, Sony seem to have 'toned down' the colour saturation to produce slightly more neutral colours which won't easily blow out primary coloured highlights (such as brightly lit red flowers for example). Otherwise things are looking good, white balance was very good, metering a little lower than the 995 / G1 (thus lower values across the board).

Red Channel Noise

Something we noticed early on with the current crop of 3 megapixel cameras was a certain amount of noise in the red channel. This was most visible in the light blue of skies or painted walls. Our colour patch test chart turned out to be a good "leveller" and a way to measure the performance of one camera to the next.

The samples below are of 40 x 40 blocks cropped from the colour comparison charts above of the Blue and Cyan patches. Each block is then broken down into it's red green and blue channels and reflected as such directly below.

It's even clearer here to see that the S85 is handling colour differently than the S75 (though not worse, just different). Channel separation is good and there's virtually NO noise visible in the red channel of both blue patches, this is not only better than the S75 but better than the rest too.

Resolution Chart 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.


Sony DSC-S85

Olympus E-10

Sony DSC-S75

Nikon Coolpix 995

Canon PowerShot G1

Measurable findings (three measurements taken for each camera):

Camera	Measurement	Absolute Res.	Extinction Res.
Sony DSC-S85	Horiz LPH	1250	1650
	Vert LPH	1200	1650
	5^o Diagonal LPH	1000	n/a
Olympus E-10	Horiz LPH	*1150	1450
	Vert LPH	*1100	1450
	5^o Diagonal LPH	900	n/a
Sony DSC-S75	Horiz LPH	1050	1400
	Vert LPH	1050	1500
	5^o Diagonal LPH	1000	n/a
Nikon Coolpix 995	Horiz LPH	*900	1300
	Vert LPH	900	1400
	5^o Diagonal LPH	900	n/a
Canon PowerShot G1	Horiz LPH	*950	1300
	Vert LPH	*950	1400
	5^o Diagonal LPH	*900	n/a

* Some moiré visible

Definition of terms:

LPH	Lines per Picture Height (to allow for different aspect ratios the measurement is the same for horizontal and vertical)
5^o Diagonal	Lines set at 5^o 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 DSC-S85's resolution performance is very impressive, with almost 1200 lines/picture height in both horizontal and vertical directions it takes the usable resolution of consumer level digital cameras to a new level. The new 4.1 megapixel sensor shows great promise, combined with a good, sharp lens (as the S85's definitely appears to be) it's capable of resolving even the tiniest detail.