Sigma SD14 vs. Nikon D40

Comparison

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SD14 image
vs
D40 image
Sigma SD14 Nikon D40
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Megapixels
4.70
6.10
Max. image resolution
2652 x 1768 x 3
3008 x 2000
Note: Sigma SD14 uses Foveon X3 image sensor, which is a new type of sensor that has 3 layers of photoelements stacked together in 1 pixel location. Traditional CCD/CMOS sensors have 1 pixel for 1 color, whereas Foveon sensor captures all 3 colors (blue, green, and red) at every pixel.

Sensor

Sensor type
Foveon
CCD
Sensor size
20.7 x 13.8 mm
23.7 x 15.6 mm
Sensor resolution
2655 x 1770
3045 x 2003
Diagonal
24.88 mm
28.37 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 : 1.29
(ratio)
Sigma SD14 Nikon D40
Surface area:
285.66 mm² vs 369.72 mm²
Difference: 84.06 mm² (29%)
D40 sensor is approx. 1.29x bigger than SD14 sensor.
Pixel pitch
7.8 µm
7.78 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: 0.02 µm (0.3%)
Pixel pitch of SD14 is approx. 0.3% higher than pixel pitch of D40.
Pixel area
60.84 µm²
60.53 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: 0.31 µm² (0.5%)
A pixel on Sigma SD14 sensor is approx. 0.5% bigger than a pixel on Nikon D40.
Pixel density
1.65 MP/cm²
1.65 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: 0 µm (0%)
Sigma SD14 and Nikon D40 have the same pixel density.
To learn about the accuracy of these numbers, click here.



Specs

Sigma SD14
Nikon D40
Crop factor
1.74
1.53
Total megapixels
4.70
6.24
Effective megapixels
4.70
6.10
Optical zoom
Digital zoom
No
No
ISO sensitivity
100, 200, 400, 800, 1600
Auto, 200 - 1600 (plus 3200 with boost)
RAW
Manual focus
Normal focus range
Macro focus range
Focal length (35mm equiv.)
Aperture priority
Yes
Yes
Max. aperture
Max. aperture (35mm equiv.)
n/a
n/a
Metering
Centre weighted, Evaluative
3D Matrix, Centre weighted, Spot
Exposure compensation
±3 EV (in 1/3 EV steps)
±5 EV (in 1/3 EV steps)
Shutter priority
Yes
Yes
Min. shutter speed
B+30 sec
30 sec
Max. shutter speed
1/4000 sec
1/4000 sec
Built-in flash
External flash
Viewfinder
Optical (pentaprism)
Optical (pentamirror)
White balance presets
8
6
Screen size
2.5"
2.5"
Screen resolution
150,000 dots
230,000 dots
Video capture
Max. video resolution
Storage types
CompactFlash type I, CompactFlash type II, Microdrive
Secure Digital
USB
USB 1.0
USB 2.0 (480 Mbit/sec)
HDMI
Wireless
GPS
Battery
Lithium-Ion rechargeable battery
Nikon EN-EL9 Lithium-Ion included
Weight
750 g
522 g
Dimensions
144 x 107.3 x 80.5 mm
126 x 64 x 94 mm
Year
2006
2006




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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

Sigma SD14 diagonal

w = 20.70 mm
h = 13.80 mm
Diagonal =  20.70² + 13.80²   = 24.88 mm

Nikon D40 diagonal

w = 23.70 mm
h = 15.60 mm
Diagonal =  23.70² + 15.60²   = 28.37 mm


Surface area

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

SD14 sensor area

Width = 20.70 mm
Height = 13.80 mm

Surface area = 20.70 × 13.80 = 285.66 mm²

D40 sensor area

Width = 23.70 mm
Height = 15.60 mm

Surface area = 23.70 × 15.60 = 369.72 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

SD14 pixel pitch

Sensor width = 20.70 mm
Sensor resolution width = 2655 pixels
Pixel pitch =   20.70  × 1000  = 7.8 µm
2655

D40 pixel pitch

Sensor width = 23.70 mm
Sensor resolution width = 3045 pixels
Pixel pitch =   23.70  × 1000  = 7.78 µm
3045


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

SD14 pixel area

Pixel pitch = 7.8 µm

Pixel area = 7.8² = 60.84 µm²

D40 pixel area

Pixel pitch = 7.78 µm

Pixel area = 7.78² = 60.53 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

SD14 pixel density

Sensor resolution width = 2655 pixels
Sensor width = 2.07 cm

Pixel density = (2655 / 2.07)² / 1000000 = 1.65 MP/cm²

D40 pixel density

Sensor resolution width = 3045 pixels
Sensor width = 2.37 cm

Pixel density = (3045 / 2.37)² / 1000000 = 1.65 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

SD14 sensor resolution

Sensor width = 20.70 mm
Sensor height = 13.80 mm
Effective megapixels = 4.70
r = 20.70/13.80 = 1.5
X =  4.70 × 1000000  = 1770
1.5
Resolution horizontal: X × r = 1770 × 1.5 = 2655
Resolution vertical: X = 1770

Sensor resolution = 2655 x 1770

D40 sensor resolution

Sensor width = 23.70 mm
Sensor height = 15.60 mm
Effective megapixels = 6.10
r = 23.70/15.60 = 1.52
X =  6.10 × 1000000  = 2003
1.52
Resolution horizontal: X × r = 2003 × 1.52 = 3045
Resolution vertical: X = 2003

Sensor resolution = 3045 x 2003


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


SD14 crop factor

Sensor diagonal in mm = 24.88 mm
Crop factor =   43.27  = 1.74
24.88

D40 crop factor

Sensor diagonal in mm = 28.37 mm
Crop factor =   43.27  = 1.53
28.37

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).

SD14 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 Sigma SD14, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Sigma SD14 is 1.74

D40 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 Nikon D40, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Nikon D40 is 1.53

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