Canon DIGITAL IXUS 55 vs. Canon PowerShot A3100 IS

Comparison

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DIGITAL IXUS 55 image
vs
PowerShot A3100 IS image
Canon DIGITAL IXUS 55 Canon PowerShot A3100 IS
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Megapixels
5.00
12.10
Max. image resolution
2592 x 1944
4000 x 3000

Sensor

Sensor type
CCD
CCD
Sensor size
1/2.5" (~ 5.75 x 4.32 mm)
1/2.3" (~ 6.16 x 4.62 mm)
Sensor resolution
2579 x 1939
4011 x 3016
Diagonal
7.19 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 : 1.15
(ratio)
Canon DIGITAL IXUS 55 Canon PowerShot A3100 IS
Surface area:
24.84 mm² vs 28.46 mm²
Difference: 3.62 mm² (15%)
A3100 IS sensor is approx. 1.15x bigger than DIGITAL IXUS 55 sensor.
Note: You are comparing cameras of different generations. There is a 5 year gap between Canon DIGITAL IXUS 55 (2005) and Canon A3100 IS (2010). All things being equal, newer sensor generations generally outperform the older.
Pixel pitch
2.23 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: 0.69 µm (45%)
Pixel pitch of DIGITAL IXUS 55 is approx. 45% higher than pixel pitch of A3100 IS.
Pixel area
4.97 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: 2.6 µm² (110%)
A pixel on Canon DIGITAL IXUS 55 sensor is approx. 110% bigger than a pixel on Canon A3100 IS.
Pixel density
20.12 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: 22.28 µm (111%)
Canon A3100 IS has approx. 111% higher pixel density than Canon DIGITAL IXUS 55.
To learn about the accuracy of these numbers, click here.



Specs

Canon DIGITAL IXUS 55
Canon A3100 IS
Crop factor
6.02
5.62
Total megapixels
5.00
Effective megapixels
5.00
12.10
Optical zoom
3x
4x
Digital zoom
Yes
Yes
ISO sensitivity
Auto, 50, 100, 200, 400
Auto, 100, 200, 400, 800, 1600
RAW
Manual focus
Normal focus range
50 cm
40 cm
Macro focus range
3 cm
3 cm
Focal length (35mm equiv.)
35 - 105 mm
35 - 140 mm
Aperture priority
No
No
Max. aperture
f2.8 - f4.9
f2.7 - f5.6
Max. aperture (35mm equiv.)
f16.9 - f29.5
f15.2 - f31.5
Metering
Multi, Center-weighted, Spot
Centre weighted, Evaluative, Spot
Exposure compensation
±2 EV (in 1/3 EV steps)
±2 EV (in 1/3 EV steps)
Shutter priority
No
No
Min. shutter speed
15 sec
15 sec
Max. shutter speed
1/1500 sec
1/1600 sec
Built-in flash
External flash
Viewfinder
Optical (tunnel)
None
White balance presets
6
6
Screen size
2.5"
2.7"
Screen resolution
115,000 dots
230,000 dots
Video capture
Max. video resolution
Storage types
SD/MMC card
SDHC, Secure Digital
USB
USB 1.0
USB 2.0 (480 Mbit/sec)
HDMI
Wireless
GPS
Battery
Lithium-Ion NB-4L battery
Lithium-Ion NB-8L rechargeable battery
Weight
155 g
125 g
Dimensions
86 x 54 x 22 mm
97 x 58 x 28 mm
Year
2005
2010




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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 DIGITAL IXUS 55 diagonal

The diagonal of DIGITAL IXUS 55 sensor is not 1/2.5 or 0.4" (10.2 mm) as you might expect, but approximately two thirds of that value - 7.19 mm. If you want to know why, see sensor sizes.

w = 5.75 mm
h = 4.32 mm
Diagonal =  5.75² + 4.32²   = 7.19 mm

Canon A3100 IS diagonal

The diagonal of A3100 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.

DIGITAL IXUS 55 sensor area

Width = 5.75 mm
Height = 4.32 mm

Surface area = 5.75 × 4.32 = 24.84 mm²

A3100 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

DIGITAL IXUS 55 pixel pitch

Sensor width = 5.75 mm
Sensor resolution width = 2579 pixels
Pixel pitch =   5.75  × 1000  = 2.23 µm
2579

A3100 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

DIGITAL IXUS 55 pixel area

Pixel pitch = 2.23 µm

Pixel area = 2.23² = 4.97 µm²

A3100 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

DIGITAL IXUS 55 pixel density

Sensor resolution width = 2579 pixels
Sensor width = 0.575 cm

Pixel density = (2579 / 0.575)² / 1000000 = 20.12 MP/cm²

A3100 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

DIGITAL IXUS 55 sensor resolution

Sensor width = 5.75 mm
Sensor height = 4.32 mm
Effective megapixels = 5.00
r = 5.75/4.32 = 1.33
X =  5.00 × 1000000  = 1939
1.33
Resolution horizontal: X × r = 1939 × 1.33 = 2579
Resolution vertical: X = 1939

Sensor resolution = 2579 x 1939

A3100 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


DIGITAL IXUS 55 crop factor

Sensor diagonal in mm = 7.19 mm
Crop factor =   43.27  = 6.02
7.19

A3100 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).

DIGITAL IXUS 55 equivalent aperture

Crop factor = 6.02
Aperture = f2.8 - f4.9

35-mm equivalent aperture = (f2.8 - f4.9) × 6.02 = f16.9 - f29.5

A3100 IS equivalent aperture

Crop factor = 5.62
Aperture = f2.7 - f5.6

35-mm equivalent aperture = (f2.7 - f5.6) × 5.62 = f15.2 - f31.5

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