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Compared to... Contd.

We've selected three cameras from our archives for comparison to the Pro90, the Sony DSC-F505V being the only one with exactly the same resolution, Nikon's Coolpix 990 as our reference 3 megapixel digital camera and Canon's G1 on whose engine the Pro90 seems to be based.

Colour Chart Comparison

Shot in daylight, Auto White Balance, EV compensation +0.3 (all cameras), measured light ~10 EV.

Canon Pro90 IS Sony DSC-F505V
Canon G1 Nikon Coolpix 990

As we'd expect the Pro90 and G1 charts look almost identical, all the cameras here are of the newer generation consumer digital cameras which have little problem properly exposing and capturing relatively accurate colours.

We're only measuring colour below. RGB values below were taken from a VGA reduced image (to average colours and eliminate JPEG artifacts) using the Eyedropper tool in Photoshop with a 5 by 5 Average Sample Size.

  Canon PowerShot
Pro90 IS
Canon PowerShot
G1
Sony
DSC-F505V
Nikon Coolpix
990
Patch White 212,207,207 214,208,208 178,182,182 201,201,201
       
Middle Gray 105,102,105 97,96,102 79,81,87 104,104,104
       
Patch Red 187,35,52 186,33,53 187,15,32 223,52,58
       
Patch Green 41,143,73 26,149,73 3,135,41 5,149,63
       
Patch Blue 47,50,109 55,49,117 40,25,123 60,50,112
       

Virtually identical results between the Pro90 and G1, though we still ee the "purists colours" from Sony's DSC-F505V.

Resolution Comparison

Shots here are of the PIMA/ISO 12233 standard resolution test chart (more available for comparison in our comparison database). Studio light, cameras set to auto, Exposure compensation +0.7 EV for all cameras. How to read the charts: All values are 1/100 th lines/picture height/width. So the "10" value equates to 1000.

Canon Powershot Pro90 IS (2.6 mp)
Sony DSC-F505V (2.6 mp)
Canon G1 (3.1 mp)
Nikon Coolpix 990 (3.1 mp)

Measurable findings (three measurements taken for each camera):

Camera Measurement Absolute Res. Extinction Res.
Canon PowerShot
Pro90 IS
Horiz LPH 900 1200
Vert LPH 900 1150
5o Diagonal LPH 900 n/a
Sony DSC-F505V Horiz LPH 950 1300
Vert LPH 950 1250
5o Diagonal 900 n/a
Canon PowerShot
G1
Horiz LPH 950 1300
Vert LPH 950 1400
5o Diagonal LPH 900 n/a
Nikon
Coolpix 990
Horiz LPH 900 1300
Vert LPH 900 1400
5o Diagonal LPH 900 n/a

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.

The Pro90 puts in a relatively good performance, despite it's lower resolution it manages to hang on to at least as much resolution as the Coolpix 990, not quite as much as it's brother the G1 and still not as sharp as the F505V which remains our king of resolution castle.

Red Channel Noise

When we first started reviewing the new batch of 3 megapixel digital cameras we noticed visible noise on flat blue areas, this turned out to be in the red channel and was thus dubbed "Red Channel Noise", we can see this as information in the red channel where there shouldn't be any. 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 beneath.

Note: The Pro90 & G1 samples were taken at ISO 50, the F505V & Coolpix 990 at ISO 100.

As we'd expect Canon's ISO 50 produces clean blues with very little noise matched by Sony's F505V which also manages to produce a purer colour.

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