Sigma SD9 vs. Sony Alpha SLT-A58
Comparison
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| Sigma SD9 | Sony Alpha SLT-A58 | ||||
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Megapixels
3.40
20.10
Max. image resolution
2268 x 1512
5456 x 3632
Note: Sigma SD9 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
CMOS
Sensor size
20.7 x 13.8 mm
23.2 x 15.4 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 »
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 »
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| Sigma SD9 | Sony Alpha SLT-A58 | |
Surface area:
| 285.66 mm² | vs | 357.28 mm² |
Difference: 71.62 mm² (25%)
Alpha SLT-A58 sensor is approx. 1.25x bigger than SD9 sensor.
Note: You are comparing sensors of vastly different generations.
There is a gap of 11 years between Sigma SD9 (2002) and
Sony Alpha SLT-A58 (2013).
Eleven years is a huge amount of time,
technology wise, resulting in newer sensor being much more
efficient than the older one.
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.
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.
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.
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: 66.19 µm² (374%)
A pixel on Sigma SD9 sensor is approx. 374% bigger than a pixel on Sony Alpha SLT-A58.
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.
Higher pixel density means smaller pixels and lower pixel density means larger pixels.
To learn about the accuracy of these numbers,
click here.
Specs
Sigma SD9
Sony Alpha SLT-A58
Total megapixels
3.40
20.40
Effective megapixels
3.40
20.10
Optical zoom
Digital zoom
No
Yes
ISO sensitivity
100, 200, 400
Auto, 100, 200, 400, 800, 1600, 3200, 6400, 12800, 16000 (25600 with boost)
RAW
Manual focus
Normal focus range
Macro focus range
Focal length (35mm equiv.)
Aperture priority
Yes
Yes
Max. aperture
Metering
Centre weighted, Matrix, Spot
Multi, Center-weighted, Spot
Exposure compensation
±3 EV (in 1/2 EV steps)
±3 EV (in 1/3 EV steps)
Shutter priority
Yes
Yes
Min. shutter speed
Bulb+30 sec
30 sec
Max. shutter speed
1/6000 sec
1/4000 sec
Built-in flash
External flash
Viewfinder
Optical (pentaprism)
Electronic
White balance presets
7
9
Screen size
1.8"
2.7"
Screen resolution
130,000 dots
460,800 dots
Video capture
Max. video resolution
1920x1080 (60i/24p)
Storage types
CompactFlash type I, CompactFlash type II, Microdrive
SD/SDHC/SDXC, Memory Stick Pro Duo/Pro-HG Duo/XC-HG Duo
USB
USB 1.0
USB 2.0 (480 Mbit/sec)
HDMI
Wireless
GPS
Battery
Lithium-Ion rechargeable battery
Rechargeable NP-FM500H battery
Weight
803 g
573 g
Dimensions
152 x 120 x 79 mm
128.6 x 95.5 x 77.7 mm
Year
2002
2013
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Diagonal
Diagonal is calculated by the use of Pythagorean theorem:
where w = sensor width and h = sensor height
| Diagonal = √ | w² + h² |
Sigma SD9 diagonal
w = 20.70 mm
h = 13.80 mm
h = 13.80 mm
| Diagonal = √ | 20.70² + 13.80² | = 24.88 mm |
Sony Alpha SLT-A58 diagonal
w = 23.20 mm
h = 15.40 mm
h = 15.40 mm
| Diagonal = √ | 23.20² + 15.40² | = 27.85 mm |
Surface area
Surface area is calculated by multiplying the width and the height of a sensor.
SD9 sensor area
Width = 20.70 mm
Height = 13.80 mm
Surface area = 20.70 × 13.80 = 285.66 mm²
Height = 13.80 mm
Surface area = 20.70 × 13.80 = 285.66 mm²
Alpha SLT-A58 sensor area
Width = 23.20 mm
Height = 15.40 mm
Surface area = 23.20 × 15.40 = 357.28 mm²
Height = 15.40 mm
Surface area = 23.20 × 15.40 = 357.28 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 |
SD9 pixel pitch
Sensor width = 20.70 mm
Sensor resolution width = 2259 pixels
Sensor resolution width = 2259 pixels
| Pixel pitch = | 20.70 | × 1000 | = 9.16 µm |
| 2259 |
Alpha SLT-A58 pixel pitch
Sensor width = 23.20 mm
Sensor resolution width = 5508 pixels
Sensor resolution width = 5508 pixels
| Pixel pitch = | 23.20 | × 1000 | = 4.21 µm |
| 5508 |
Pixel area
The area of one pixel can be calculated by simply squaring the pixel pitch:
You could also divide sensor surface area with effective megapixels:
Pixel area = pixel pitch²
You could also divide sensor surface area with effective megapixels:
| Pixel area = | sensor surface area in mm² |
| effective megapixels |
SD9 pixel area
Pixel pitch = 9.16 µm
Pixel area = 9.16² = 83.91 µm²
Pixel area = 9.16² = 83.91 µm²
Alpha SLT-A58 pixel area
Pixel pitch = 4.21 µm
Pixel area = 4.21² = 17.72 µm²
Pixel area = 4.21² = 17.72 µm²
Pixel density
Pixel density can be calculated with the following formula:
One could also use this 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 |
SD9 pixel density
Sensor resolution width = 2259 pixels
Sensor width = 2.07 cm
Pixel density = (2259 / 2.07)² / 1000000 = 1.19 MP/cm²
Sensor width = 2.07 cm
Pixel density = (2259 / 2.07)² / 1000000 = 1.19 MP/cm²
Alpha SLT-A58 pixel density
Sensor resolution width = 5508 pixels
Sensor width = 2.32 cm
Pixel density = (5508 / 2.32)² / 1000000 = 5.64 MP/cm²
Sensor width = 2.32 cm
Pixel density = (5508 / 2.32)² / 1000000 = 5.64 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:
3. To get sensor resolution we then multiply X with the corresponding ratio:
Resolution horizontal: X × r
Resolution vertical: X
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 → |
|
Resolution horizontal: X × r
Resolution vertical: X
SD9 sensor resolution
Sensor width = 20.70 mm
Sensor height = 13.80 mm
Effective megapixels = 3.40
Resolution horizontal: X × r = 1506 × 1.5 = 2259
Resolution vertical: X = 1506
Sensor resolution = 2259 x 1506
Sensor height = 13.80 mm
Effective megapixels = 3.40
| r = 20.70/13.80 = 1.5 |
|
Resolution vertical: X = 1506
Sensor resolution = 2259 x 1506
Alpha SLT-A58 sensor resolution
Sensor width = 23.20 mm
Sensor height = 15.40 mm
Effective megapixels = 20.10
Resolution horizontal: X × r = 3648 × 1.51 = 5508
Resolution vertical: X = 3648
Sensor resolution = 5508 x 3648
Sensor height = 15.40 mm
Effective megapixels = 20.10
| r = 23.20/15.40 = 1.51 |
|
Resolution vertical: X = 3648
Sensor resolution = 5508 x 3648
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 |
SD9 crop factor
Sensor diagonal in mm = 24.88 mm
| Crop factor = | 43.27 | = 1.74 |
| 24.88 |
Alpha SLT-A58 crop factor
Sensor diagonal in mm = 27.85 mm
| Crop factor = | 43.27 | = 1.55 |
| 27.85 |
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).
SD9 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 SD9, take the aperture of the lens
you're using and multiply it with crop factor.
Crop factor for Sigma SD9 is 1.74
Crop factor for Sigma SD9 is 1.74
Alpha SLT-A58 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
Sony Alpha SLT-A58, take the aperture of the lens
you're using and multiply it with crop factor.
Crop factor for Sony Alpha SLT-A58 is 1.55
Crop factor for Sony Alpha SLT-A58 is 1.55
Enter your screen size (diagonal)
My screen size is
inches
Actual size is currently adjusted to screen.
If your screen (phone, tablet, or monitor) is not in diagonal, then the actual size of a sensor won't be shown correctly.
If your screen (phone, tablet, or monitor) is not in diagonal, then the actual size of a sensor won't be shown correctly.