Sony Alpha a7R III vs. Olympus OM-D E-M1 Mark II

Comparison

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Alpha a7R III image
vs
OM-D E-M1 Mark II image
Sony Alpha a7R III Olympus OM-D E-M1 Mark II
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Megapixels
42.40
20.40
Max. image resolution
7952 x 5304
5184 x 3888

Sensor

Sensor type
CMOS
CMOS
Sensor size
35.9 x 24 mm
Four Thirds (17.3 x 13 mm)
Sensor resolution
7976 x 5317
5208 x 3916
Diagonal
43.18 mm
21.64 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

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vs
3.83 : 1
(ratio)
Sony Alpha a7R III Olympus OM-D E-M1 Mark II
Surface area:
861.60 mm² vs 224.90 mm²
Difference: 636.7 mm² (283%)
Alpha a7R III sensor is approx. 3.83x bigger than OM-D E-M1 Mark II sensor.
Pixel pitch
4.5 µm
3.32 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: 1.18 µm (36%)
Pixel pitch of Alpha a7R III is approx. 36% higher than pixel pitch of OM-D E-M1 Mark II.
Pixel area
20.25 µm²
11.02 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: 9.23 µm² (84%)
A pixel on Sony Alpha a7R III sensor is approx. 84% bigger than a pixel on Olympus OM-D E-M1 Mark II.
Pixel density
4.94 MP/cm²
9.06 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: 4.12 µm (83%)
Olympus OM-D E-M1 Mark II has approx. 83% higher pixel density than Sony Alpha a7R III.
To learn about the accuracy of these numbers, click here.

Specs

Sony Alpha a7R III
Olympus OM-D E-M1 Mark II
Crop factor
1
2
Total megapixels
43.60
21.80
Effective megapixels
42.40
20.40
Optical zoom
 
 
Digital zoom
Yes
Yes
ISO sensitivity
Auto, 100-32000 (expandable to 50-102400)
Auto, 200-25600 (extends down to 64)
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, 1 EV steps)
±5 EV (in 1/3 EV, 1/2 EV, 1 EV steps)
Shutter priority
Yes
Yes
Min. shutter speed
30 sec
60 sec
Max. shutter speed
1/8000 sec
1/32000 sec
Built-in flash
External flash
Viewfinder
Electronic
Electronic
White balance presets
10
7
Screen size
3"
3"
Screen resolution
1,440,000 dots
1,037,000 dots
Video capture
Max. video resolution
3840x2160 (30p/25p/24p)
4096x2160 (24p)
Storage types
SD/SDHC/SDXC/MS PRO Duo
Dual SD/SDHC/SDXC
USB
USB 3.0 (5 GBit/sec)
USB 3.0 (5 GBit/sec)
HDMI
Wireless
GPS
Battery
NP-FZ100 lithium-ion battery
BLH-1 lithium-ion battery
Weight
657 g
574 g
Dimensions
126.9 x 95.6 x 73.7 mm
134.1 x 90.9 x 68.9 mm
Year
2017
2016



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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 a7R III diagonal

w = 35.90 mm
h = 24.00 mm
Diagonal =  35.90² + 24.00²   = 43.18 mm

Olympus OM-D E-M1 Mark II diagonal

w = 17.30 mm
h = 13.00 mm
Diagonal =  17.30² + 13.00²   = 21.64 mm


Surface area

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

Alpha a7R III sensor area

Width = 35.90 mm
Height = 24.00 mm

Surface area = 35.90 × 24.00 = 861.60 mm²

OM-D E-M1 Mark II sensor area

Width = 17.30 mm
Height = 13.00 mm

Surface area = 17.30 × 13.00 = 224.90 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

Alpha a7R III pixel pitch

Sensor width = 35.90 mm
Sensor resolution width = 7976 pixels
Pixel pitch =   35.90  × 1000  = 4.5 µm
7976

OM-D E-M1 Mark II pixel pitch

Sensor width = 17.30 mm
Sensor resolution width = 5208 pixels
Pixel pitch =   17.30  × 1000  = 3.32 µm
5208


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 a7R III pixel area

Pixel pitch = 4.5 µm

Pixel area = 4.5² = 20.25 µm²

OM-D E-M1 Mark II pixel area

Pixel pitch = 3.32 µm

Pixel area = 3.32² = 11.02 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 a7R III pixel density

Sensor resolution width = 7976 pixels
Sensor width = 3.59 cm

Pixel density = (7976 / 3.59)² / 1000000 = 4.94 MP/cm²

OM-D E-M1 Mark II pixel density

Sensor resolution width = 5208 pixels
Sensor width = 1.73 cm

Pixel density = (5208 / 1.73)² / 1000000 = 9.06 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 a7R III sensor resolution

Sensor width = 35.90 mm
Sensor height = 24.00 mm
Effective megapixels = 42.40
r = 35.90/24.00 = 1.5
X =  42.40 × 1000000  = 5317
1.5
Resolution horizontal: X × r = 5317 × 1.5 = 7976
Resolution vertical: X = 5317

Sensor resolution = 7976 x 5317

OM-D E-M1 Mark II sensor resolution

Sensor width = 17.30 mm
Sensor height = 13.00 mm
Effective megapixels = 20.40
r = 17.30/13.00 = 1.33
X =  20.40 × 1000000  = 3916
1.33
Resolution horizontal: X × r = 3916 × 1.33 = 5208
Resolution vertical: X = 3916

Sensor resolution = 5208 x 3916


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 a7R III crop factor

Sensor diagonal in mm = 43.18 mm
Crop factor =   43.27  = 1
43.18

OM-D E-M1 Mark II crop factor

Sensor diagonal in mm = 21.64 mm
Crop factor =   43.27  = 2
21.64

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 a7R III 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 a7R III, take the aperture of the lens you're using and multiply it with crop factor.

Since crop factor for Sony Alpha a7R III is 1, the equivalent aperture is aperture.

OM-D E-M1 Mark II 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 Olympus OM-D E-M1 Mark II, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Olympus OM-D E-M1 Mark II is 2

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