Canon PowerShot A50 vs. Canon PowerShot SD550

Comparison

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Canon PowerShot A50

Canon PowerShot SD550

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Megapixels

1.20

7.10

Max. image resolution

1280 x 960

3072 x 2304

Sensor

Sensor type

CCD

Sensor size

1/3" (~ 4.8 x 3.6 mm)

1/1.8" (~ 7.11 x 5.33 mm)

Sensor resolution

1264 x 950

3072 x 2310

Diagonal

6.00 mm

8.89 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	:	2.19
(ratio)

Canon PowerShot A50		Canon PowerShot SD550

Surface area:

17.28 mm²

37.90 mm²

Difference: 20.62 mm² (119%)

SD550 sensor is approx. 2.19x bigger than A50 sensor.

Note: You are comparing sensors of very different generations. There is a gap of 6 years between Canon A50 (1999) and Canon SD550 (2005). Six years is a lot of time in terms of technology, meaning newer sensors are overall much more efficient than the older ones.

Pixel pitch

3.8 µm

2.31 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: 1.49 µm (65%)

Pixel pitch of A50 is approx. 65% higher than pixel pitch of SD550.

Pixel area

14.44 µm²

5.34 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:

Pixel area difference: 9.1 µm² (170%)

A pixel on Canon A50 sensor is approx. 170% bigger than a pixel on Canon SD550.

Pixel density

6.93 MP/cm²

18.67 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: 11.74 µm (169%)

Canon SD550 has approx. 169% higher pixel density than Canon A50.

To learn about the accuracy of these numbers, click here.

Specs

Canon A50

Canon SD550

Crop factor

7.21

4.87

Total megapixels

1.30

7.40

Effective megapixels

1.20

7.10

Optical zoom

2.5x

Digital zoom

Yes

ISO sensitivity

100, 200, 400

Auto, 50, 100, 200, 400

RAW

Manual focus

Normal focus range

50 cm

Macro focus range

17 cm

5 cm

Focal length (35mm equiv.)

28 - 70 mm

37 - 111 mm

Aperture priority

Max. aperture

f2.6 - f4.0

f2.8 - f4.9

Max. aperture (35mm equiv.)

f18.7 - f28.8

f13.6 - f23.9

Metering

Multi, Center-weighted, Spot

Exposure compensation

±2 EV (in 1/3 EV steps)

Shutter priority

Min. shutter speed

2 sec

15 sec

Max. shutter speed

1/750 sec

1/2000 sec

Built-in flash

External flash

Viewfinder

Optical (tunnel)

White balance presets

Screen size

2.5"

Screen resolution

120,000 dots

115,000 dots

Video capture

Max. video resolution

Storage types

Compact Flash

SD/MMC card

USB

USB 1.0

HDMI

Wireless

GPS

Battery

Canon NiMH

Lithium-Ion NB-3L battery

Weight

290 g

185 g

Dimensions

103 x 68 x 37 mm

90 x 57 x 27 mm

Year

1999

2005

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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 A50 diagonal

The diagonal of A50 sensor is not 1/3 or 0.33" (8.5 mm) as you might expect, but approximately two thirds of that value - 6 mm. If you want to know why, see sensor sizes.

w = 4.80 mm
h = 3.60 mm

Diagonal = √

4.80² + 3.60²

= 6.00 mm

Canon SD550 diagonal

The diagonal of SD550 sensor is not 1/1.8 or 0.56" (14.1 mm) as you might expect, but approximately two thirds of that value - 8.89 mm. If you want to know why, see sensor sizes.

w = 7.11 mm
h = 5.33 mm

Diagonal = √

7.11² + 5.33²

= 8.89 mm

Surface area

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

A50 sensor area

Width = 4.80 mm
Height = 3.60 mm

Surface area = 4.80 × 3.60 = 17.28 mm²

SD550 sensor area

Width = 7.11 mm
Height = 5.33 mm

Surface area = 7.11 × 5.33 = 37.90 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

A50 pixel pitch

Sensor width = 4.80 mm
Sensor resolution width = 1264 pixels

Pixel pitch =	4.80	× 1000	= 3.8 µm
	1264

SD550 pixel pitch

Sensor width = 7.11 mm
Sensor resolution width = 3072 pixels

Pixel pitch =	7.11	× 1000	= 2.31 µm
	3072

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

A50 pixel area

Pixel pitch = 3.8 µm

Pixel area = 3.8² = 14.44 µm²

SD550 pixel area

Pixel pitch = 2.31 µm

Pixel area = 2.31² = 5.34 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

A50 pixel density

Sensor resolution width = 1264 pixels
Sensor width = 0.48 cm

Pixel density = (1264 / 0.48)² / 1000000 = 6.93 MP/cm²

SD550 pixel density

Sensor resolution width = 3072 pixels
Sensor width = 0.711 cm

Pixel density = (3072 / 0.711)² / 1000000 = 18.67 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

A50 sensor resolution

Sensor width = 4.80 mm
Sensor height = 3.60 mm
Effective megapixels = 1.20

r = 4.80/3.60 = 1.33

X = √	1.20 × 1000000	= 950
	1.33

Resolution horizontal: X × r = 950 × 1.33 = 1264
Resolution vertical: X = 950

Sensor resolution = 1264 x 950

SD550 sensor resolution

Sensor width = 7.11 mm
Sensor height = 5.33 mm
Effective megapixels = 7.10

r = 7.11/5.33 = 1.33

X = √	7.10 × 1000000	= 2310
	1.33

Resolution horizontal: X × r = 2310 × 1.33 = 3072
Resolution vertical: X = 2310

Sensor resolution = 3072 x 2310

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

A50 crop factor

Sensor diagonal in mm = 6.00 mm

Crop factor =	43.27	= 7.21
	6.00

SD550 crop factor

Sensor diagonal in mm = 8.89 mm

Crop factor =	43.27	= 4.87
	8.89

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).

A50 equivalent aperture

Crop factor = 7.21
Aperture = f2.6 - f4.0

35-mm equivalent aperture = (f2.6 - f4.0) × 7.21 = f18.7 - f28.8

SD550 equivalent aperture

Crop factor = 4.87
Aperture = f2.8 - f4.9

35-mm equivalent aperture = (f2.8 - f4.9) × 4.87 = f13.6 - f23.9

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