Pentax Optio E90 vs. Nikon Coolpix 7900

Comparison

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Pentax Optio E90

Nikon Coolpix 7900

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Megapixels

10.00

7.10

Max. image resolution

3648 x 2736

3072 x 2304

Sensor

Sensor type

CCD

Sensor size

1/2.3" (~ 6.16 x 4.62 mm)

1/1.8" (~ 7.11 x 5.33 mm)

Sensor resolution

3647 x 2742

3072 x 2310

Diagonal

7.70 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	:	1.33
(ratio)

Pentax Optio E90		Nikon Coolpix 7900

Surface area:

28.46 mm²

37.90 mm²

Difference: 9.44 mm² (33%)

7900 sensor is approx. 1.33x bigger than E90 sensor.

Note: You are comparing cameras of different generations. There is a 5 year gap between Pentax E90 (2010) and Nikon 7900 (2005). All things being equal, newer sensor generations generally outperform the older.

Pixel pitch

1.69 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: 0.62 µm (37%)

Pixel pitch of 7900 is approx. 37% higher than pixel pitch of E90.

Pixel area

2.86 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: 2.48 µm² (87%)

A pixel on Nikon 7900 sensor is approx. 87% bigger than a pixel on Pentax E90.

Pixel density

35.05 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: 16.38 µm (88%)

Pentax E90 has approx. 88% higher pixel density than Nikon 7900.

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

Specs

Pentax E90

Nikon 7900

Crop factor

5.62

4.87

Total megapixels

10.70

7.10

Effective megapixels

10.00

7.10

Optical zoom

Digital zoom

Yes

ISO sensitivity

Auto, 100 - 1600

Auto

RAW

Manual focus

Normal focus range

50 cm

30 cm

Macro focus range

6 cm

4 cm

Focal length (35mm equiv.)

32 - 95 mm

38 - 114 mm

Aperture priority

Max. aperture

f2.9 - f5.2

f2.8 - f4.9

Max. aperture (35mm equiv.)

f16.3 - f29.2

f13.6 - f23.9

Metering

Multi-segment

Multi, Center-weighted, Average

Exposure compensation

±2 EV (in 1/3 EV steps)

Shutter priority

Min. shutter speed

4 sec

Max. shutter speed

1/2000 sec

Built-in flash

External flash

Viewfinder

None

Optical (tunnel)

White balance presets

Screen size

2.7"

Screen resolution

230,000 dots

115,000 dots

Video capture

Max. video resolution

Storage types

SDHC, Secure Digital

Secure Digital

USB

USB 2.0 (480 Mbit/sec)

USB 1.0

HDMI

Wireless

GPS

Battery

2 x AA batteries (Alkaline, Lithium or NiMH)

Nikon EN-EL5 Lithium-Ion included

Weight

122 g

150 g

Dimensions

93 x 60 x 28 mm

88 x 60 x 36.5 mm

Year

2010

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

Pentax E90 diagonal

The diagonal of E90 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

Nikon 7900 diagonal

The diagonal of 7900 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.

E90 sensor area

Width = 6.16 mm
Height = 4.62 mm

Surface area = 6.16 × 4.62 = 28.46 mm²

7900 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

E90 pixel pitch

Sensor width = 6.16 mm
Sensor resolution width = 3647 pixels

Pixel pitch =	6.16	× 1000	= 1.69 µm
	3647

7900 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

E90 pixel area

Pixel pitch = 1.69 µm

Pixel area = 1.69² = 2.86 µm²

7900 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

E90 pixel density

Sensor resolution width = 3647 pixels
Sensor width = 0.616 cm

Pixel density = (3647 / 0.616)² / 1000000 = 35.05 MP/cm²

7900 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

E90 sensor resolution

Sensor width = 6.16 mm
Sensor height = 4.62 mm
Effective megapixels = 10.00

r = 6.16/4.62 = 1.33

X = √	10.00 × 1000000	= 2742
	1.33

Resolution horizontal: X × r = 2742 × 1.33 = 3647
Resolution vertical: X = 2742

Sensor resolution = 3647 x 2742

7900 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

E90 crop factor

Sensor diagonal in mm = 7.70 mm

Crop factor =	43.27	= 5.62
	7.70

7900 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).

E90 equivalent aperture

Crop factor = 5.62
Aperture = f2.9 - f5.2

35-mm equivalent aperture = (f2.9 - f5.2) × 5.62 = f16.3 - f29.2

7900 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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