Canon IXY 31S vs. Canon PowerShot SX20 IS

Comparison

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IXY 31S image
vs
PowerShot SX20 IS image
Canon IXY 31S Canon PowerShot SX20 IS
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Megapixels
12.10
12.10
Max. image resolution
4000 x 3000
4000 x 3000

Sensor

Sensor type
CMOS
CCD
Sensor size
1/2.3" (~ 6.16 x 4.62 mm)
1/2.3" (~ 6.16 x 4.62 mm)
Sensor resolution
4011 x 3016
4011 x 3016
Diagonal
7.70 mm
7.70 mm
Sensor size comparison
Sensor size is generally a good indicator of the quality of the camera. Sensors can vary greatly in size. As a general rule, the bigger the sensor, the better the image quality.

Bigger sensors are more effective because they have more surface area to capture light. An important factor when comparing digital cameras is also camera generation. Generally, newer sensors will outperform the older.

Learn more about sensor sizes »

Actual sensor size

Note: Actual size is set to screen → change »
vs
1 : 1
(ratio)
Canon IXY 31S Canon PowerShot SX20 IS
Surface area:
28.46 mm² vs 28.46 mm²
Difference: 0 mm² (0%)
IXY 31S and SX20 IS sensors are the same size.
Note: You are comparing cameras of different generations. There is a 2 year gap between Canon IXY 31S (2011) and Canon SX20 IS (2009). All things being equal, newer sensor generations generally outperform the older.
Pixel pitch
1.54 µm
1.54 µm
Pixel pitch tells you the distance from the center of one pixel (photosite) to the center of the next. It tells you how close the pixels are to each other.

The bigger the pixel pitch, the further apart they are and the bigger each pixel is. Bigger pixels tend to have better signal to noise ratio and greater dynamic range.
Difference: 0 µm (0%)
IXY 31S and SX20 IS have the same pixel pitch.
Pixel area
2.37 µm²
2.37 µm²
Pixel or photosite area affects how much light per pixel can be gathered. The larger it is the more light can be collected by a single pixel.

Larger pixels have the potential to collect more photons, resulting in greater dynamic range, while smaller pixels provide higher resolutions (more detail) for a given sensor size.
Relative pixel sizes:
vs
Pixel area difference: 0 µm² (0%)
Canon IXY 31S and Canon SX20 IS have the same pixel area.
Pixel density
42.4 MP/cm²
42.4 MP/cm²
Pixel density tells you how many million pixels fit or would fit in one square cm of the sensor.

Higher pixel density means smaller pixels and lower pixel density means larger pixels.
Difference: 0 µm (0%)
Canon IXY 31S and Canon SX20 IS have the same pixel density.
To learn about the accuracy of these numbers, click here.



Specs

Canon IXY 31S
Canon SX20 IS
Crop factor
5.62
5.62
Total megapixels
12.40
Effective megapixels
12.10
12.10
Optical zoom
4.4x
20x
Digital zoom
Yes
Yes
ISO sensitivity
Auto, 125 - 3200
Auto, 80, 100, 200, 400, 800, 1600
RAW
Manual focus
Normal focus range
40 cm
30 cm
Macro focus range
3 cm
Focal length (35mm equiv.)
24 - 105 mm
28 - 560 mm
Aperture priority
Yes
Yes
Max. aperture
f2.0 - f5.8
f2.8 - f5.7
Max. aperture (35mm equiv.)
f11.2 - f32.6
f15.7 - f32
Metering
Centre weighted, Evaluative, Spot
Centre weighted, Multi-segment, Spot
Exposure compensation
±2 EV (in 1/3 EV steps)
±2 EV (in 1/3 EV steps)
Shutter priority
Yes
Yes
Min. shutter speed
15 sec
15 sec
Max. shutter speed
1/1600 sec
1/3200 sec
Built-in flash
External flash
Viewfinder
None
Electronic
White balance presets
6
6
Screen size
3.2"
2.5"
Screen resolution
461,000 dots
230,000 dots
Video capture
Max. video resolution
Storage types
SDHC, SDXC, Secure Digital
SDHC, Secure Digital
USB
USB 2.0 (480 Mbit/sec)
USB 2.0 (480 Mbit/sec)
HDMI
Wireless
GPS
Battery
Lithium-Ion NB-6L rechargeable battery
4 x AA batteries (Alkaline or NiMH)
Weight
185 g
560 g
Dimensions
100.6 x 55.4 x 25.0 mm
124.0 x 88.3 x 86.9 mm
Year
2011
2009




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Diagonal

Diagonal is calculated by the use of Pythagorean theorem:
Diagonal =  w² + h²
where w = sensor width and h = sensor height

Canon IXY 31S diagonal

The diagonal of IXY 31S sensor is not 1/2.3 or 0.43" (11 mm) as you might expect, but approximately two thirds of that value - 7.7 mm. If you want to know why, see sensor sizes.

w = 6.16 mm
h = 4.62 mm
Diagonal =  6.16² + 4.62²   = 7.70 mm

Canon SX20 IS diagonal

The diagonal of SX20 IS sensor is not 1/2.3 or 0.43" (11 mm) as you might expect, but approximately two thirds of that value - 7.7 mm. If you want to know why, see sensor sizes.

w = 6.16 mm
h = 4.62 mm
Diagonal =  6.16² + 4.62²   = 7.70 mm


Surface area

Surface area is calculated by multiplying the width and the height of a sensor.

IXY 31S sensor area

Width = 6.16 mm
Height = 4.62 mm

Surface area = 6.16 × 4.62 = 28.46 mm²

SX20 IS sensor area

Width = 6.16 mm
Height = 4.62 mm

Surface area = 6.16 × 4.62 = 28.46 mm²


Pixel pitch

Pixel pitch is the distance from the center of one pixel to the center of the next measured in micrometers (µm). It can be calculated with the following formula:
Pixel pitch =   sensor width in mm  × 1000
sensor resolution width in pixels

IXY 31S pixel pitch

Sensor width = 6.16 mm
Sensor resolution width = 4011 pixels
Pixel pitch =   6.16  × 1000  = 1.54 µm
4011

SX20 IS pixel pitch

Sensor width = 6.16 mm
Sensor resolution width = 4011 pixels
Pixel pitch =   6.16  × 1000  = 1.54 µm
4011


Pixel area

The area of one pixel can be calculated by simply squaring the pixel pitch:
Pixel area = pixel pitch²

You could also divide sensor surface area with effective megapixels:
Pixel area =   sensor surface area in mm²
effective megapixels

IXY 31S pixel area

Pixel pitch = 1.54 µm

Pixel area = 1.54² = 2.37 µm²

SX20 IS pixel area

Pixel pitch = 1.54 µm

Pixel area = 1.54² = 2.37 µm²


Pixel density

Pixel density can be calculated with the following formula:
Pixel density =  ( sensor resolution width in pixels )² / 1000000
sensor width in cm

One could also use this formula:
Pixel density =   effective megapixels × 1000000  / 10000
sensor surface area in mm²

IXY 31S pixel density

Sensor resolution width = 4011 pixels
Sensor width = 0.616 cm

Pixel density = (4011 / 0.616)² / 1000000 = 42.4 MP/cm²

SX20 IS pixel density

Sensor resolution width = 4011 pixels
Sensor width = 0.616 cm

Pixel density = (4011 / 0.616)² / 1000000 = 42.4 MP/cm²


Sensor resolution

Sensor resolution is calculated from sensor size and effective megapixels. It's slightly higher than maximum (not interpolated) image resolution which is usually stated on camera specifications. Sensor resolution is used in pixel pitch, pixel area, and pixel density formula. For sake of simplicity, we're going to calculate it in 3 stages.

1. First we need to find the ratio between horizontal and vertical length by dividing the former with the latter (aspect ratio). It's usually 1.33 (4:3) or 1.5 (3:2), but not always.

2. With the ratio (r) known we can calculate the X from the formula below, where X is a vertical number of pixels:
(X × r) × X = effective megapixels × 1000000    →   
X =  effective megapixels × 1000000
r
3. To get sensor resolution we then multiply X with the corresponding ratio:

Resolution horizontal: X × r
Resolution vertical: X

IXY 31S sensor resolution

Sensor width = 6.16 mm
Sensor height = 4.62 mm
Effective megapixels = 12.10
r = 6.16/4.62 = 1.33
X =  12.10 × 1000000  = 3016
1.33
Resolution horizontal: X × r = 3016 × 1.33 = 4011
Resolution vertical: X = 3016

Sensor resolution = 4011 x 3016

SX20 IS sensor resolution

Sensor width = 6.16 mm
Sensor height = 4.62 mm
Effective megapixels = 12.10
r = 6.16/4.62 = 1.33
X =  12.10 × 1000000  = 3016
1.33
Resolution horizontal: X × r = 3016 × 1.33 = 4011
Resolution vertical: X = 3016

Sensor resolution = 4011 x 3016


Crop factor

Crop factor or focal length multiplier is calculated by dividing the diagonal of 35 mm film (43.27 mm) with the diagonal of the sensor.
Crop factor =   43.27 mm
sensor diagonal in mm


IXY 31S crop factor

Sensor diagonal in mm = 7.70 mm
Crop factor =   43.27  = 5.62
7.70

SX20 IS crop factor

Sensor diagonal in mm = 7.70 mm
Crop factor =   43.27  = 5.62
7.70

35 mm equivalent aperture

Equivalent aperture (in 135 film terms) is calculated by multiplying lens aperture with crop factor (a.k.a. focal length multiplier).

IXY 31S equivalent aperture

Crop factor = 5.62
Aperture = f2.0 - f5.8

35-mm equivalent aperture = (f2.0 - f5.8) × 5.62 = f11.2 - f32.6

SX20 IS equivalent aperture

Crop factor = 5.62
Aperture = f2.8 - f5.7

35-mm equivalent aperture = (f2.8 - f5.7) × 5.62 = f15.7 - f32

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