Sony a7R IIIA vs Sony a5100

This is a full comparison between the cameras Sony a7R IIIA and Sony a5100. We compare them by looking at the categories you see below.

Manufacturing

These cameras are both manufactured by Sony.

Sony a7R IIIA were released 2021 and Sony a5100 was released 2014. That is a 7 years difference. In tech, this period can be of interest since technology is always improving, etc.

Camera Released
Sony a7R IIIA 2021
Sony a5100 2014

Type of camera

Both these cameras are Mirrorless cameras. No difference there.

Sensors / crop factor

These cameras have different sensors. Sony a7R IIIA has a "Sony Full Frame"-sensor while Sony a5100 has a "Sony APS-C"-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 a7R IIIA 50 mm
Full-frame sensor
No crop factor/focal length multiplier
Sony a5100 75 mm
Sony APS-C 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)

Resolution

Sony a7R IIIA has a 42 MP (Megapixels) resolution while Sony a5100 has 24 MP. If we break down this in more detail this is the data behind the numbers:

Camera Megapixels
Sony a7R IIIA 42 MP
42177408 pixels
7952 x 5304
Sony a5100 24 MP
24000000 pixels
6000 x 4000

Sony a7R IIIA has a 76 % larger resolution than Sony a5100. 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 a7R IIIA has a larger ISO-range than Sony a5100. Sony a7R IIIA has an ISO range that stretches from 100 to 32000 while Sony a5100 has 100 to 25600.

Camera ISO Range
Sony a7R IIIA 100-32000
Sony a5100 100-25600

Autofocus and lens compatibility

Both of these cameras have a built-in autofocus motor. Some lenses, that support autofocus, do not have an autofocus motor of their own but this won't cause any problems with these two cameras.

Here is a complete overview of which lenses work with each camera:
Lens compatibility chart for Sony a7R IIIA
Lens compatibility chart for Sony a5100

Pictures per second

Depending on what you are shooting the FPS, or frames/pictures per second, can definitely be of interest. Sony a7R IIIA can shoot up to 10 pictures per seconds and Sony a5100 can shoot up to 6 pictures per seconds.

Camera FPS (Frames per second)
Sony a7R IIIA 10
Sony a5100 6

Ability to record movies

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

In this case, both Sony a7R IIIA and Sony a5100 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 a7R IIIA weighs 657 gr (equal to 1.45 lb) which is 132% heavier than Sony a5100 and its 283 gr (or 0.62 lb).

Camera Weight
Sony a7R IIIA 657 gr
1.45 lb
Sony a5100 283 gr
0.62 lb

Sony a7R IIIA vs Sony a5100 Specs

Below you will find the complete and detailed technical specs for both Sony a7R IIIA and Sony a5100, 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 a7R IIIA
Sony a5100
Name Sony a7R IIIA Sony a5100
Manufacturer Sony Sony
Release Date and Price
Sony a7R IIIA
Sony a5100
Release Year 2021 2014
Release Date 2021-04-07 2014-08-18
MSRP 3199 USD 549 USD
Buy it today
Camera Type
Sony a7R IIIA
Sony a5100
Camera Type Mirrorless Mirrorless
Sensor
Sony a7R IIIA
Sony a5100
Sensor Size Full Frame (approx 36 x 24 mm) APS-C (approx 23.5 x 15.6 mm)
Sensor Type BSI-CMOS CMOS
Resolution 7952 x 5304 pixels 6000 x 4000 pixels
Megapixels 42 MP 24 MP
Image Processor BIONZ X Bionz X
Image
Sony a7R IIIA
Sony a5100
ISO Range 100 - 32000 100 - 25600
White Balance Presets 10 10
Custom White Balance Yes Yes
Image Stabilization Yes
(Sensor-Shift (5-axis))
No
Image Stabilization CIPA Rating 5.5 stops 0 stops
Uncompressed format RAW RAW
Optics & Focus
Sony a7R IIIA
Sony a5100
Autofocus Motor Yes Yes
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
Touch
Face Detection
LiveView
Focus Points 399 179
Lens Mount Sony E

See Compatible Lenses
Sony E

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
APS-C Sensor (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 a7R IIIA
Sony a5100
Articulated LCD Tilting Tilting
Screen size 3” 3”
Screen dots 2360000 921600
Touch screen Yes Yes
Screen type TFT LCD TFT LCD
Live view Yes Yes
Viewfinder Type Electronic No Viewfinder
Viewfinder Coverage 100%
Viewfinder Magnification 0.78x
Viewfinder Resolution 3686400 0
Photography features
Sony a7R IIIA
Sony a5100
Frames per second 10 fps 6 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 4 meters
External Flash Yes No
Self-Timer Yes Yes
Time-lapse No Yes
Metering modes Multi
Center Weighted
Spot
Multi
Center Weighted
Spot
Exposure Compensation +/- 5 (at 1/3 EV, 1/2 EV steps) +/- 3 (at 1/3 EV steps)
Videography features
Sony a7R IIIA
Sony a5100
Video recording Yes Yes
Video format MPEG4
XAVC-S
AVCHD
MPEG4
XF-AVC
AVCHD
Video resolution 1920 x 1080
3840 x 2160
1440 x 1080
1920 x 1080
Built-in Microphone Yes Yes
Built-in Speakers Yes Yes
Storage
Sony a7R IIIA
Sony a5100
Memory Card SD/SDHC
Memory Stick Pro Duo
SD/SDHC
Connectivity
Sony a7R IIIA
Sony a5100
HDMI Output Yes Yes
Microphone Port Yes No
Headphone Port Yes No
Wireless Yes
Built-in (802.11b/g/n + NFC + Bluetooth)
Yes
Built-in (802.11b/g/n with NFC)
Remote Control Yes (wired, wireless, smartphone) Yes (wired or PC)
GPS No No
Body & Dimensions
Sony a7R IIIA
Sony a5100
Enviromentally sealed Yes Yes
Battery Battery Pack Battery Pack
Battery Details NP-FZ100 lithium-ion battery and charger
NP-FW50 lithium-ion battery and USB charger
Battery Life (CIPA) 650 shots 400 shots
Width 127 mm 110 mm
Height 96 mm 63 mm
Depth 74 mm 36 mm
Weight 657 gram 283 gram