Compared to... (contd.)

Now we'll compare the DSC-F707 to a few other cameras from our test archives. Here we're comparing colour and resolution to the Minolta DiMAGE 7, Sony DSC-S85 and Fujifilm FinePix 6900Z.

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.

Sony DSC-F707 Minolta DiMAGE 7 (converted to sRGB)
Sony DSC-S85 Fujifilm FinePix 6900Z
The green cast we observed on the pre-production F707 has now gone, as well as an overall 'toning down' (reduction in saturation) of all colours (especially red). A far more balanced (if still a little 'bright') colour performance.

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.





Fujifilm FinePix

Black 18,18,20 29,30,32 17,17,19 37,32,31
Middle Gray 80,89,91 85,89,97 76,81,79 112,116,112
White 176,189,190 220,224,226 188,189,189 238,237,227
Magenta 182,16,82 212,40,116 170,12,124 254,27,119
Red 178,9,4 208,44,56 176,0,40 255,48,39
Yellow 175,180,37 215,221,45 181,180,14 253,211,46
Green 8,135,66 26,136,58 24,131,27 14,153,17
Cyan 12,148,198 22,144,215 23,158,175 0,174,231
Blue 36,21,98 45,31,104 23,31,112 33,39,126

Observations of the Sony DSC-F707 colour balance:

  • Gone is the green cast we saw on pre-production camera
  • White balance is lacking a little red on the gray scale patches (similar to DSC-S85)
  • Red, Yellow and Green saturation has been toned down (since pre-produciton) - better
  • Cyan patch is more accurate (compared to pre-production) - better

Red Channel Noise

Something we noticed early on with the current crop of digital 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.

A pretty good performance, there is some 'texture' in the red channel on the dark blue patch but this wouldn't be particulary noticeable in every day shots.

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.

Horizontal resolution Vertical resolution 5 degree diagonal res.
Sony DSC-F707
Minolta DiMAGE 7
Sony DSC-S85
Fujifilm FinePix 6900Z

Measurable findings (three measurements taken for each camera):

Camera Measurement Absolute Res. Extinction Res.
Sony DSC-F707 Horiz LPH 1450  1800 
Vert LPH 1300  1800 
5o Diagonal LPH 1000  n/a 
Minolta DiMAGE 7 Horiz LPH *1300  1450 
Vert LPH *1150  1450 
5o Diagonal LPH 900  n/a 
Sony DSC-S85 Horiz LPH 1200  *1650 
Vert LPH 1150  *1650 
5o Diagonal LPH 1000  n/a 
Fujifilm FinePix 6900Z Horiz LPH *1150 1400 
Vert LPH *1150  1450 
5o Diagonal LPH 900  n/a 

* Moiré becomes visible

Definition of terms:

LPH Lines per Picture Height (to allow for different aspect ratios the measurement is the same for horizontal and vertical)
5o Diagonal Lines set at 5o 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.

This is more like it. Here's what I'd expected from the new 5 megapixel digital cameras, around 1400 lines/picture height in both horizontal and vertical directions. The DSC-F707 really shines and shows how sharp its lens is and how good it is at resolving fine detail. What's additionally impressive is the way that resolution detail carries on well into the 1800's. And it does so without visible moiré. Based on these results the DSC-F707 is now the new king of resolution for consumer level digital cameras (at the time of writing this review).