HP Photosmart R717 vs. Olympus Stylus 820

Comparison

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HP Photosmart R717

Olympus Stylus 820

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Megapixels

6.20

8.00

Max. image resolution

2864 x 2160

3264 x 2488

Sensor

Sensor type

CCD

Sensor size

1/1.8" (~ 7.11 x 5.33 mm)

1/2.3" (~ 6.16 x 4.62 mm)

Sensor resolution

2871 x 2159

3262 x 2453

Diagonal

8.89 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
1.33	:	1
(ratio)

HP Photosmart R717		Olympus Stylus 820

Surface area:

37.90 mm²

28.46 mm²

Difference: 9.44 mm² (33%)

R717 sensor is approx. 1.33x bigger than 820 sensor.

Note: You are comparing cameras of different generations. There is a 2 year gap between HP R717 (2005) and Olympus 820 (2007). All things being equal, newer sensor generations generally outperform the older.

Pixel pitch

2.48 µm

1.89 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: 0.59 µm (31%)

Pixel pitch of R717 is approx. 31% higher than pixel pitch of 820.

Pixel area

6.15 µm²

3.57 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: 2.58 µm² (72%)

A pixel on HP R717 sensor is approx. 72% bigger than a pixel on Olympus 820.

Pixel density

16.31 MP/cm²

28.04 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: 11.73 µm (72%)

Olympus 820 has approx. 72% higher pixel density than HP R717.

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

Specs

HP R717

Olympus 820

Crop factor

4.87

5.62

Total megapixels

8.50

Effective megapixels

8.00

Optical zoom

Digital zoom

Yes

ISO sensitivity

Auto, 50, 100, 200, 400

Auto, (50 - 400), 80 - 1600, 3200 @ 3MP

RAW

Manual focus

Normal focus range

50 cm

70 cm

Macro focus range

14 cm

3 cm

Focal length (35mm equiv.)

39 - 117 mm

36 - 180 mm

Aperture priority

Yes

Max. aperture

f2.8 - f4.9

f3.3 - f5.0

Max. aperture (35mm equiv.)

f13.6 - f23.9

f18.5 - f28.1

Metering

Centre weighted, Matrix, Spot

Multi, Center-weighted, Spot

Exposure compensation

±3 EV (in 1/3 EV steps)

±2 EV (in 1/3 EV steps)

Shutter priority

Min. shutter speed

16 sec

4 sec

Max. shutter speed

1/2000 sec

Built-in flash

External flash

Viewfinder

Optical (tunnel)

None

White balance presets

Screen size

1.8"

2.7"

Screen resolution

130,572 dots

230,000 dots

Video capture

Max. video resolution

Storage types

MultiMedia, Secure Digital

xD Picture Card, Internal

USB

USB 1.0

USB 2.0 (480 Mbit/sec)

HDMI

Wireless

GPS

Battery

HP Lithium-Ion rechargeable supplied

Lithium-Ion rechargeable

Weight

180 g

165 g

Dimensions

96 x 60 x 35 mm

96 x 56 x 24 mm

Year

2005

2007

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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

HP R717 diagonal

The diagonal of R717 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

Olympus 820 diagonal

The diagonal of 820 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.

R717 sensor area

Width = 7.11 mm
Height = 5.33 mm

Surface area = 7.11 × 5.33 = 37.90 mm²

820 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

R717 pixel pitch

Sensor width = 7.11 mm
Sensor resolution width = 2871 pixels

Pixel pitch =	7.11	× 1000	= 2.48 µm
	2871

820 pixel pitch

Sensor width = 6.16 mm
Sensor resolution width = 3262 pixels

Pixel pitch =	6.16	× 1000	= 1.89 µm
	3262

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

R717 pixel area

Pixel pitch = 2.48 µm

Pixel area = 2.48² = 6.15 µm²

820 pixel area

Pixel pitch = 1.89 µm

Pixel area = 1.89² = 3.57 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

R717 pixel density

Sensor resolution width = 2871 pixels
Sensor width = 0.711 cm

Pixel density = (2871 / 0.711)² / 1000000 = 16.31 MP/cm²

820 pixel density

Sensor resolution width = 3262 pixels
Sensor width = 0.616 cm

Pixel density = (3262 / 0.616)² / 1000000 = 28.04 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

R717 sensor resolution

Sensor width = 7.11 mm
Sensor height = 5.33 mm
Effective megapixels = 6.20

r = 7.11/5.33 = 1.33

X = √	6.20 × 1000000	= 2159
	1.33

Resolution horizontal: X × r = 2159 × 1.33 = 2871
Resolution vertical: X = 2159

Sensor resolution = 2871 x 2159

820 sensor resolution

Sensor width = 6.16 mm
Sensor height = 4.62 mm
Effective megapixels = 8.00

r = 6.16/4.62 = 1.33

X = √	8.00 × 1000000	= 2453
	1.33

Resolution horizontal: X × r = 2453 × 1.33 = 3262
Resolution vertical: X = 2453

Sensor resolution = 3262 x 2453

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

R717 crop factor

Sensor diagonal in mm = 8.89 mm

Crop factor =	43.27	= 4.87
	8.89

820 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).

R717 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

820 equivalent aperture

Crop factor = 5.62
Aperture = f3.3 - f5.0

35-mm equivalent aperture = (f3.3 - f5.0) × 5.62 = f18.5 - f28.1

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