Acer CS-6531 vs. Pentax K-5

Comparison

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CS-6531 image
vs
K-5 image
Acer CS-6531 Pentax K-5
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Megapixels
6.16
16.30
Max. image resolution
2816 x 2112
4928 x 3264

Sensor

Sensor type
CCD
CMOS
Sensor size
1/2.5" (~ 5.75 x 4.32 mm)
23.6 x 15.7 mm
Sensor resolution
2862 x 2152
4944 x 3296
Diagonal
7.19 mm
28.35 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 : 14.92
(ratio)
Acer CS-6531 Pentax K-5
Surface area:
24.84 mm² vs 370.52 mm²
Difference: 345.68 mm² (1392%)
K-5 sensor is approx. 14.92x bigger than CS-6531 sensor.
Note: You are comparing cameras of different generations. There is a 5 year gap between Acer CS-6531 (2005) and Pentax K-5 (2010). All things being equal, newer sensor generations generally outperform the older.
Pixel pitch
2.01 µm
4.77 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: 2.76 µm (137%)
Pixel pitch of K-5 is approx. 137% higher than pixel pitch of CS-6531.
Pixel area
4.04 µm²
22.75 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: 18.71 µm² (463%)
A pixel on Pentax K-5 sensor is approx. 463% bigger than a pixel on Acer CS-6531.
Pixel density
24.77 MP/cm²
4.39 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: 20.38 µm (464%)
Acer CS-6531 has approx. 464% higher pixel density than Pentax K-5.
To learn about the accuracy of these numbers, click here.



Specs

Acer CS-6531
Pentax K-5
Crop factor
6.02
1.53
Total megapixels
16.90
Effective megapixels
16.30
Optical zoom
Yes
Digital zoom
Yes
No
ISO sensitivity
Auto, 50, 100, 200, 400
Auto, 100 - 12800
RAW
Manual focus
Normal focus range
50 cm
Macro focus range
6 cm
Focal length (35mm equiv.)
32 - 96 mm
Aperture priority
No
Yes
Max. aperture
f2.8 - f4.8
Max. aperture (35mm equiv.)
f16.9 - f28.9
n/a
Metering
Multi-segment
Centre weighted, Multi-segment, Spot
Exposure compensation
±2 EV (in 1/3 EV steps)
±5 EV (in 1/3 EV, 1/2 EV steps)
Shutter priority
No
Yes
Min. shutter speed
1/2 sec
30 sec
Max. shutter speed
1/2000 sec
1/8000 sec
Built-in flash
External flash
Viewfinder
None
Optical (pentaprism)
White balance presets
6
9
Screen size
2.5"
3"
Screen resolution
201,096 dots
921,000 dots
Video capture
Max. video resolution
Storage types
Secure Digital
SDHC, Secure Digital
USB
USB 1.1
USB 2.0 (480 Mbit/sec)
HDMI
Wireless
GPS
Battery
Li-Ion
Lithium-Ion D-LI90 rechargeable battery
Weight
130 g
740 g
Dimensions
89 x 55 x 24 mm
131 x 97 x 73 mm
Year
2005
2010




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vs

Diagonal

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

Acer CS-6531 diagonal

The diagonal of CS-6531 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

Pentax K-5 diagonal

w = 23.60 mm
h = 15.70 mm
Diagonal =  23.60² + 15.70²   = 28.35 mm


Surface area

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

CS-6531 sensor area

Width = 5.75 mm
Height = 4.32 mm

Surface area = 5.75 × 4.32 = 24.84 mm²

K-5 sensor area

Width = 23.60 mm
Height = 15.70 mm

Surface area = 23.60 × 15.70 = 370.52 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

CS-6531 pixel pitch

Sensor width = 5.75 mm
Sensor resolution width = 2862 pixels
Pixel pitch =   5.75  × 1000  = 2.01 µm
2862

K-5 pixel pitch

Sensor width = 23.60 mm
Sensor resolution width = 4944 pixels
Pixel pitch =   23.60  × 1000  = 4.77 µm
4944


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

CS-6531 pixel area

Pixel pitch = 2.01 µm

Pixel area = 2.01² = 4.04 µm²

K-5 pixel area

Pixel pitch = 4.77 µm

Pixel area = 4.77² = 22.75 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

CS-6531 pixel density

Sensor resolution width = 2862 pixels
Sensor width = 0.575 cm

Pixel density = (2862 / 0.575)² / 1000000 = 24.77 MP/cm²

K-5 pixel density

Sensor resolution width = 4944 pixels
Sensor width = 2.36 cm

Pixel density = (4944 / 2.36)² / 1000000 = 4.39 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

CS-6531 sensor resolution

Sensor width = 5.75 mm
Sensor height = 4.32 mm
Effective megapixels = 6.16
r = 5.75/4.32 = 1.33
X =  6.16 × 1000000  = 2152
1.33
Resolution horizontal: X × r = 2152 × 1.33 = 2862
Resolution vertical: X = 2152

Sensor resolution = 2862 x 2152

K-5 sensor resolution

Sensor width = 23.60 mm
Sensor height = 15.70 mm
Effective megapixels = 16.30
r = 23.60/15.70 = 1.5
X =  16.30 × 1000000  = 3296
1.5
Resolution horizontal: X × r = 3296 × 1.5 = 4944
Resolution vertical: X = 3296

Sensor resolution = 4944 x 3296


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


CS-6531 crop factor

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

K-5 crop factor

Sensor diagonal in mm = 28.35 mm
Crop factor =   43.27  = 1.53
28.35

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).

CS-6531 equivalent aperture

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

35-mm equivalent aperture = (f2.8 - f4.8) × 6.02 = f16.9 - f28.9

K-5 equivalent aperture

Aperture is a lens characteristic, so it's calculated only for fixed lens cameras. If you want to know the equivalent aperture for Pentax K-5, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Pentax K-5 is 1.53

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