Olympus OM-D E-M1X vs. Sony Alpha a7R III

Comparison

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OM-D E-M1X image
vs
Alpha a7R III image
Olympus OM-D E-M1X Sony Alpha a7R III
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Megapixels
20.40
42.40
Max. image resolution
5184 x 3888
7952 x 5304

Sensor

Sensor type
CMOS
CMOS
Sensor size
Four Thirds (17.3 x 13 mm)
35.9 x 24 mm
Sensor resolution
5208 x 3916
7976 x 5317
Diagonal
21.64 mm
43.18 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 : 3.83
(ratio)
Olympus OM-D E-M1X Sony Alpha a7R III
Surface area:
224.90 mm² vs 861.60 mm²
Difference: 636.7 mm² (283%)
Alpha a7R III sensor is approx. 3.83x bigger than OM-D E-M1X sensor.
Note: You are comparing cameras of different generations. There is a 2 year gap between Olympus OM-D E-M1X (2019) and Sony Alpha a7R III (2017). All things being equal, newer sensor generations generally outperform the older.
Pixel pitch
3.32 µm
4.5 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-M1X.
Pixel area
11.02 µm²
20.25 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-M1X.
Pixel density
9.06 MP/cm²
4.94 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-M1X has approx. 83% higher pixel density than Sony Alpha a7R III.
To learn about the accuracy of these numbers, click here.



Specs

Olympus OM-D E-M1X
Sony Alpha a7R III
Crop factor
2
1
Total megapixels
21.80
43.60
Effective megapixels
20.40
42.40
Optical zoom
 
 
Digital zoom
Yes
Yes
ISO sensitivity
Auto, 200-25600 (extendable to 64)
Auto, 100-32000 (expandable to 50-102400)
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, Highlight-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
60 sec
30 sec
Max. shutter speed
1/32000 sec
1/8000 sec
Built-in flash
External flash
Viewfinder
Electronic
Electronic
White balance presets
7
10
Screen size
3"
3"
Screen resolution
1,037,000 dots
1,440,000 dots
Video capture
Max. video resolution
4096x2160 (24p)
3840x2160 (30p/25p/24p)
Storage types
SD/SDHC/SDXC
SD/SDHC/SDXC/MS PRO Duo
USB
USB 3.0 (5 GBit/sec)
USB 3.0 (5 GBit/sec)
HDMI
Wireless
GPS
Battery
Two BLH-1 Li-ion batteries
NP-FZ100 lithium-ion battery
Weight
997 g
657 g
Dimensions
144.4 x 146.8 x 75.4 mm
126.9 x 95.6 x 73.7 mm
Year
2019
2017




Choose cameras to compare

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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

Olympus OM-D E-M1X diagonal

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

Sony Alpha a7R III diagonal

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


Surface area

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

OM-D E-M1X sensor area

Width = 17.30 mm
Height = 13.00 mm

Surface area = 17.30 × 13.00 = 224.90 mm²

Alpha a7R III sensor area

Width = 35.90 mm
Height = 24.00 mm

Surface area = 35.90 × 24.00 = 861.60 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

OM-D E-M1X pixel pitch

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

Alpha a7R III pixel pitch

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


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-M1X pixel area

Pixel pitch = 3.32 µm

Pixel area = 3.32² = 11.02 µm²

Alpha a7R III pixel area

Pixel pitch = 4.5 µm

Pixel area = 4.5² = 20.25 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-M1X pixel density

Sensor resolution width = 5208 pixels
Sensor width = 1.73 cm

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

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


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-M1X 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 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


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-M1X crop factor

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

Alpha a7R III crop factor

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

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-M1X 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-M1X, take the aperture of the lens you're using and multiply it with crop factor.

Crop factor for Olympus OM-D E-M1X is 2

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.

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