Olympus OM-D E-M5 Mark III vs Sony Alpha A7 III Comparison

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OM-D E-M5 Mark III image
vs
Alpha A7 III image
Olympus OM-D E-M5 Mark III Sony Alpha A7 III
Megapixels
20.40
24.20
Image resolution
5184 x 3888
6000 x 4000

Sensor

Sensor type
CMOS
CMOS
Sensor size
Four Thirds (17.3 x 13 mm)
35.6 x 23.8 mm
Sensor resolution
5208 x 3916
6026 x 4017
Diagonal
21.64 mm
42.82 mm
Compare sensor size:

Sensor Size

Actual size is set to screen
vs
1:3.77
(ratio)
Olympus OM-D E-M5 Mark III Sony Alpha A7 III
Surface area:
224.90 mm² vs 847.28 mm²
Difference: 622.38 mm² (277%)
Alpha A7 III sensor is ~3.77x bigger than OM-D E-M5 Mark III's.
Pixel pitch
3.32 µm
5.91 µm
Difference: 2.59 µm (78%)
Pixel pitch of Alpha A7 III is ~78% higher than OM-D E-M5 Mark III's.
Pixel area
11.02 µm²
34.93 µm²
Relative pixel sizes:
vs
Pixel area difference: 23.91 µm² (217%)
Pixel on Sony Alpha A7 III sensor is ~217% bigger than Olympus OM-D E-M5 Mark III's.
Pixel density
9.06 MP/cm²
2.87 MP/cm²
Difference: 6.19 µm (216%)
Olympus OM-D E-M5 Mark III has ~216% higher pixel density than Sony Alpha A7 III's.

Specs

Olympus OM-D E-M5 Mark III
Sony Alpha A7 III
Crop factor
2
1.01
Megapixels
21.80
25.30
Optical zoom
 
Digital zoom
ISO range
Auto, 64-25600
100-25600 (expands to 50 - 204800)
RAW support
Manual focus
Focus range
n/a
Macro focus range
n/a
Focal length
n/a
Aperture priority
Max. aperture
n/a
Metering types
Multi, Center-weighted, Spot
Multi, Center-weighted, Highlight-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 steps)
Shutter priority
Shutter speed (min)
60s
30s
Shutter speed (max)
1/32000s
1/8000s
Built-in flash
External flash
Viewfinder type
Electronic
Electronic
White balance
7
10
Screen size
3"
3"
Screen resolution
1,037,000 dots
921,600 dots
Video available
Video resolution
4096x2160
3840x2160
Video modes
24p
30p/25p/24p
Storage type
SD/SDHC/SDXC
SD/SDHC/SDXC, MS Duo/Pro Duo/Pro-HG Duo
USB
USB 2.0 (480 Mbit/sec)
USB 3.0 (5 GBit/sec)
HDMI
Wireless support
GPS
Battery model
BLS-50
NP-FZ100
Battery type
lithium-ion
lithium-ion
Weight
414g
650g
Body size
125.3 x 85.2 x 49.7 mm
126.9 x 95.6 x 73.7 mm
Released
2019
2018


Compare various cameras

vs

Diagonal

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

Olympus OM-D E-M5 Mark III diagonal

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

Sony Alpha A7 III diagonal

w = 35.60 mm
h = 23.80 mm
Diagonal =  35.60² + 23.80²   = 42.82 mm


Surface area

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

OM-D E-M5 Mark III sensor area

Width = 17.30 mm
Height = 13.00 mm

Surface area = 17.30 × 13.00 = 224.90 mm²

Alpha A7 III sensor area

Width = 35.60 mm
Height = 23.80 mm

Surface area = 35.60 × 23.80 = 847.28 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

OM-D E-M5 Mark III pixel pitch

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

Alpha A7 III pixel pitch

Sensor width = 35.60 mm
Sensor resolution width = 6026 pixels
Pixel pitch =   35.60  × 1000  = 5.91 µm
6026


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

OM-D E-M5 Mark III pixel area

Pixel pitch = 3.32 µm

Pixel area = 3.32² = 11.02 µm²

Alpha A7 III pixel area

Pixel pitch = 5.91 µm

Pixel area = 5.91² = 34.93 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

OM-D E-M5 Mark III pixel density

Sensor resolution width = 5208 pixels
Sensor width = 1.73 cm

Pixel density = (5208 / 1.73)² / 1000000 = 9.06 MP/cm²

Alpha A7 III pixel density

Sensor resolution width = 6026 pixels
Sensor width = 3.56 cm

Pixel density = (6026 / 3.56)² / 1000000 = 2.87 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

OM-D E-M5 Mark III 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

Alpha A7 III sensor resolution

Sensor width = 35.60 mm
Sensor height = 23.80 mm
Effective megapixels = 24.20
r = 35.60/23.80 = 1.5
X =  24.20 × 1000000  = 4017
1.5
Resolution horizontal: X × r = 4017 × 1.5 = 6026
Resolution vertical: X = 4017

Sensor resolution = 6026 x 4017


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


OM-D E-M5 Mark III crop factor

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

Alpha A7 III crop factor

Sensor diagonal in mm = 42.82 mm
Crop factor =   43.27  = 1.01
42.82

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).

OM-D E-M5 Mark 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 Olympus OM-D E-M5 Mark III, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Olympus OM-D E-M5 Mark III is 2

Alpha A7 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 A7 III, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Sony Alpha A7 III is 1.01

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