Sony a9 vs Nikon D5100

This is a full comparison between the cameras Sony a9 and Nikon D5100. We compare them by looking at the categories you see below.

Manufacturing

Sony a9 is manufacturered by Sony but Nikon D5100 is from Nikon. Both Sony and Nikon are well known brands though.

Sony a9 were released 2017 and Nikon D5100 was released 2011. That is a 6 years difference. In tech, this period can be of interest since technology is always improving, etc.

Camera Released
Sony a9 2017
Nikon D5100 2011

Type of camera

Sony a9 is a Mirrorless camera while Nikon D5100 is a DSLR camera. More information about their differences will come soon.

Sensors / crop factor

These cameras have different sensors. Sony a9 has a "Sony Full Frame"-sensor while Nikon D5100 has a "Nikon DX"-sensor, and their difference in sensors will also affect the crop factor and experience focal length. See the table below.

Camera Focal length, 50mm f/1.8 **
Sony a9 50 mm
Full-frame sensor
No crop factor/focal length multiplier
Nikon D5100 75 mm
Nikon DX sensor
Crop factor/focal length multiplier by * 1.5

** Experienced focal length when using a lens such as a common "50mm f/1.8"

Learn more about crop factor and focal length multiplier here:
Camera selection can affect the focal length (Sony)
Camera selection can affect the focal length (Nikon)

Resolution

Sony a9 has a 24 MP (Megapixels) resolution while Nikon D5100 has 16,2 MP. If we break down this in more detail this is the data behind the numbers:

Camera Megapixels
Sony a9 24 MP
24000000 pixels
6000 x 4000
Nikon D5100 16,2 MP
16084992 pixels
4928 x 3264

Sony a9 has a 49 % larger resolution than Nikon D5100. This could give you more details in the picture but also a possibility to crop more in the pictures, afterward while editing the pictures, if needed that is.

ISO range

Sony a9 has a larger ISO-range than Nikon D5100. Sony a9 has an ISO range that stretches from 100 to 51200 while Nikon D5100 has 100 to 6400.

Camera ISO Range
Sony a9 100-51200
Nikon D5100 100-6400

Autofocus and lens compatibility

There is a big difference between these two cameras. Sony a9 has a built-in autofocus motor but Nikon D5100 does not. If you want to be able to use autofocus on Nikon D5100 there is a need for having an autofocus motor inside the lens. We really encourage you to look closely at our lens compatibility charts at the links below.

Here is a complete overview of which lenses work with each camera:
Lens compatibility chart for Sony a9
Lens compatibility chart for Nikon D5100

Pictures per second

Depending on what you are shooting the FPS, or frames/pictures per second, can definitely be of interest. Sony a9 can shoot up to 20 pictures per seconds and Nikon D5100 can shoot up to 4 pictures per seconds.

Camera FPS (Frames per second)
Sony a9 20
Nikon D5100 4

Ability to record movies

It is becoming more and more popular to record movies with digital cameras.

In this case, both Sony a9 and Nikon D5100 can shoot movies.

Weight

The weight of the camera can be an extremely important factor, especially if the camera is about to be used, or carried around, for several hours at a time.

Sony a9 weighs 673 gr (equal to 1.48 lb) which is 10% heavier than Nikon D5100 and its 611 gr (or 1.35 lb).

Camera Weight
Sony a9 673 gr
1.48 lb
Nikon D5100 611 gr
1.35 lb

Sony a9 vs Nikon D5100 Specs

Below you will find the complete and detailed technical specs for both Sony a9 and Nikon D5100, next to each other. Each category of data is a link to an article covering the subject, giving you a deeper understanding so you can better understand the strengths and weaknesses of the two camera models.

Product
Sony a9
Nikon D5100
Name Sony a9 Nikon D5100
Manufacturer Sony Nikon
Release Date and Price
Sony a9
Nikon D5100
Release Year 2017 2011
Release Date 2017-04-19 2011-04-05
MSRP 4499 USD 359 USD
Buy it today
Camera Type
Sony a9
Nikon D5100
Camera Type Mirrorless DSLR
Sensor
Sony a9
Nikon D5100
Sensor Size Full Frame (approx 36 x 24 mm) APS-C (approx 23.7 x 15.5 mm)
Also known as "DX"
Sensor Type Stacked CMOS CMOS
Resolution 6000 x 4000 pixels 4928 x 3264 pixels
Megapixels 24 MP 16,2 MP
Image Processor Bionz X EXPEED 2
Image
Sony a9
Nikon D5100
ISO Range 100 - 51200 100 - 6400
White Balance Presets 10 12
Custom White Balance Yes Yes
Image Stabilization Yes
(Sensor-Shift (5-axis))
No
Image Stabilization CIPA Rating 0 stops 0 stops
Uncompressed format RAW RAW
Optics & Focus
Sony a9
Nikon D5100
Autofocus Motor Yes No
Autofocus Contract Detect (sensor)
Phase Detect
Multi Area
Center
Selective Single Point
Tracking
Single
Continuous
Touch
Face Detection
LiveView
Contract Detect (sensor)
Phase Detect
Multi Area
Center
Selective Single Point
Tracking
Single
Continuous
Face Detection
LiveView
Focus Points 693 11
Lens Mount Sony E

See Compatible Lenses
Nikon F

See Compatible Lenses
Focal Length Multiplier Full frame
No multiplier
Example:
24 mm remains 24 mm
50 mm remains 50 mm
100 mm remains 100 mm
200 mm remains 200 mm
DX / APS-C (1.5x)
1.5x multiplier
Example:
24 mm becomes 36 mm
50 mm becomes 75 mm
100 mm becomes 150 mm
200 mm becomes 300 mm
Screen & Viewfinder
Sony a9
Nikon D5100
Articulated LCD Tilting Fully articulated
Screen size 3” 3#
Screen dots 1440000 921000
Touch screen Yes No
Screen type TFT LCD TFT LCD monitor
Live view Yes Yes
Viewfinder Type Electronic Optical (pentamirror)
Viewfinder Coverage 100% 95%
Viewfinder Magnification 0.78x 0.78× (0.52× 35mm equiv.)
Viewfinder Resolution 3686400 N/A
Photography features
Sony a9
Nikon D5100
Frames per second 20 fps 4 fps
Minimum Shutter Speed 30 seconds 30 seconds
Maximum Shutter Speed 1/8000 seconds 1/4000 seconds
Built-in Flash No Yes
Built-in Flash Range N/A 12 meters
External Flash Yes Yes
Self-Timer Yes Yes
Time-lapse No Yes
Metering modes Multi
Center Weighted
Highlight Weighted
Spot
Average
Multi
Center Weighted
Spot
Exposure Compensation +/- 5 (at 1/3 EV, 1/2 EV steps) +/- 5 (at 1/3 EV, 1/2 EV steps)
Videography features
Sony a9
Nikon D5100
Video recording Yes Yes
Video format MPEG4
H.264
AVCHD
MPEG4
Video resolution 1280 x 720
1920 x 1080
3840 x 2160
1280 x 720
1920 x 1080
Built-in Microphone Yes Yes
Built-in Speakers Yes Yes
Storage
Sony a9
Nikon D5100
Memory Card SD/SDHC
SD/SDHC
Connectivity
Sony a9
Nikon D5100
HDMI Output Yes Yes
Microphone Port Yes Yes
Headphone Port Yes No
Wireless Yes
Built-in (802.11/b/g/n with NFC)
Yes
Eye-Fi Connected
Remote Control Yes (Wired or wireless) Yes (Optional ML-L3)
GPS No Yes
Optional with GP-1
Body & Dimensions
Sony a9
Nikon D5100
Enviromentally sealed Yes No
Battery Battery Pack Battery Pack
Battery Details NP-FZ100
Lithium-Ion EN-EL14 rechargeable battery & charger
Battery Life (CIPA) 650 shots N/A
Width 127 mm 128 mm
Height 96 mm 97 mm
Depth 63 mm 79 mm
Weight 673 gram 611 gram