Sony Alpha SLT-A99 vs. Sony Alpha NEX-7

Comparison

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Alpha SLT-A99 image
vs
Alpha NEX-7 image
Sony Alpha SLT-A99 Sony Alpha NEX-7
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Megapixels
24.30
24.30
Max. image resolution
6000 x 4000
6000 x 4000

Sensor

Sensor type
CMOS
CMOS
Sensor size
35.8 x 23.8 mm
23.5 x 15.6 mm
Sensor resolution
6038 x 4025
6058 x 4012
Diagonal
42.99 mm
28.21 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
2.32 : 1
(ratio)
Sony Alpha SLT-A99 Sony Alpha NEX-7
Surface area:
852.04 mm² vs 366.60 mm²
Difference: 485.44 mm² (132%)
Alpha SLT-A99 sensor is approx. 2.32x bigger than Alpha NEX-7 sensor.
Pixel pitch
5.93 µm
3.88 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: 2.05 µm (53%)
Pixel pitch of Alpha SLT-A99 is approx. 53% higher than pixel pitch of Alpha NEX-7.
Pixel area
35.16 µm²
15.05 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: 20.11 µm² (134%)
A pixel on Sony Alpha SLT-A99 sensor is approx. 134% bigger than a pixel on Sony Alpha NEX-7.
Pixel density
2.84 MP/cm²
6.65 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: 3.81 µm (134%)
Sony Alpha NEX-7 has approx. 134% higher pixel density than Sony Alpha SLT-A99.
To learn about the accuracy of these numbers, click here.

Specs

Sony Alpha SLT-A99
Sony Alpha NEX-7
Crop factor
1.01
1.53
Total megapixels
24.70
24.70
Effective megapixels
24.30
24.30
Optical zoom
Digital zoom
No
No
ISO sensitivity
Auto, 100, 200, 400, 800, 1600, 3200, 6400, 12800, 25600
Auto, 100, 200, 400, 800, 1600, 3200, 6400, 12800, 16000
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
Multi, Center-weighted, Spot
Multi, Center-weighted, Spot
Exposure compensation
±5 EV (in 1/3 EV, 1/2 EV steps)
±5 EV (in 1/3 EV steps)
Shutter priority
Yes
Yes
Min. shutter speed
30 sec
30 sec
Max. shutter speed
1/8000 sec
1/4000 sec
Built-in flash
External flash
Viewfinder
Electronic
Electronic
White balance presets
8
6
Screen size
3"
3"
Screen resolution
1,229,000 dots
921,000 dots
Video capture
Max. video resolution
Storage types
Memory Stick PRO Duo/Pro-HG Duo; SD, SDHC and SDXC
SD/SDHC/SDXC/Memory Stick Pro Duo/ Pro-HG Duo
USB
USB 2.0 (480 Mbit/sec)
USB 2.0 (480 Mbit/sec)
HDMI
Wireless
GPS
Battery
Lithium-Ion NP-FM500H rechargeable battery
Lithium-Ion NP-FW50 rechargeable battery
Weight
812 g
400 g
Dimensions
147 x 111 x 78 mm
120 x 67 x 43 mm
Year
2012
2011



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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

Sony Alpha SLT-A99 diagonal

w = 35.80 mm
h = 23.80 mm
Diagonal =  35.80² + 23.80²   = 42.99 mm

Sony Alpha NEX-7 diagonal

w = 23.50 mm
h = 15.60 mm
Diagonal =  23.50² + 15.60²   = 28.21 mm


Surface area

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

Alpha SLT-A99 sensor area

Width = 35.80 mm
Height = 23.80 mm

Surface area = 35.80 × 23.80 = 852.04 mm²

Alpha NEX-7 sensor area

Width = 23.50 mm
Height = 15.60 mm

Surface area = 23.50 × 15.60 = 366.60 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

Alpha SLT-A99 pixel pitch

Sensor width = 35.80 mm
Sensor resolution width = 6038 pixels
Pixel pitch =   35.80  × 1000  = 5.93 µm
6038

Alpha NEX-7 pixel pitch

Sensor width = 23.50 mm
Sensor resolution width = 6058 pixels
Pixel pitch =   23.50  × 1000  = 3.88 µm
6058


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

Alpha SLT-A99 pixel area

Pixel pitch = 5.93 µm

Pixel area = 5.93² = 35.16 µm²

Alpha NEX-7 pixel area

Pixel pitch = 3.88 µm

Pixel area = 3.88² = 15.05 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

Alpha SLT-A99 pixel density

Sensor resolution width = 6038 pixels
Sensor width = 3.58 cm

Pixel density = (6038 / 3.58)² / 1000000 = 2.84 MP/cm²

Alpha NEX-7 pixel density

Sensor resolution width = 6058 pixels
Sensor width = 2.35 cm

Pixel density = (6058 / 2.35)² / 1000000 = 6.65 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

Alpha SLT-A99 sensor resolution

Sensor width = 35.80 mm
Sensor height = 23.80 mm
Effective megapixels = 24.30
r = 35.80/23.80 = 1.5
X =  24.30 × 1000000  = 4025
1.5
Resolution horizontal: X × r = 4025 × 1.5 = 6038
Resolution vertical: X = 4025

Sensor resolution = 6038 x 4025

Alpha NEX-7 sensor resolution

Sensor width = 23.50 mm
Sensor height = 15.60 mm
Effective megapixels = 24.30
r = 23.50/15.60 = 1.51
X =  24.30 × 1000000  = 4012
1.51
Resolution horizontal: X × r = 4012 × 1.51 = 6058
Resolution vertical: X = 4012

Sensor resolution = 6058 x 4012


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


Alpha SLT-A99 crop factor

Sensor diagonal in mm = 42.99 mm
Crop factor =   43.27  = 1.01
42.99

Alpha NEX-7 crop factor

Sensor diagonal in mm = 28.21 mm
Crop factor =   43.27  = 1.53
28.21

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).

Alpha SLT-A99 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-A99, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Sony Alpha SLT-A99 is 1.01

Alpha NEX-7 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 NEX-7, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Sony Alpha NEX-7 is 1.53

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