Nikon D5100 vs Sony A9 III
The Nikon D5100 and the Sony Alpha A9 III are two digital cameras that were officially introduced, respectively, in April 2011 and November 2023. The D5100 is a DSLR, while the A9 III is a mirrorless interchangeable lens camera. The cameras are based on an APS-C (D5100) and a full frame (A9 III) sensor. The Nikon has a resolution of 16.1 megapixels, whereas the Sony provides 24 MP.
Below is an overview of the main specs of the two cameras as a starting point for the comparison.

Check D5100 offers at
ebay.com

Check A9 III price at
amazon.com
Going beyond this snapshot of core features and characteristics, what are the differences between the Nikon D5100 and the Sony Alpha A9 III? Which one should you buy? Read on to find out how these two cameras compare with respect to their body size, their imaging sensors, their shooting features, their input-output connections, and their reception by expert reviewers.
Body comparison
The physical size and weight of the Nikon D5100 and the Sony A9 III are illustrated in the side-by-side display below. The two cameras are presented according to their relative size. Three successive views from the front, the top, and the rear are shown. All size dimensions are rounded to the nearest millimeter.



If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A9 III is notably larger (6 percent) than the Nikon D5100. Moreover, the A9 III is markedly heavier (25 percent) than the D5100. It is noteworthy in this context that the A9 III is splash and dust-proof, while the D5100 does not feature any corresponding weather-sealing.
The above size and weight comparisons are to some extent incomplete since they do not consider the interchangeable lenses that both of these cameras require. A larger imaging sensor will tend to go along with bigger and heavier lenses, although exceptions exist. You can compare the optics available for the two cameras in the Nikon Lens Catalog (D5100) and the Sony FE Lens Catalog (A9 III). Mirrorless cameras, such as the A9 III, have moreover the advantage that they can use many lenses from other systems via adapters, as they have a relatively short flange to focal plane distance.
Concerning battery life, the D5100 gets 660 shots out of its Nikon EN-EL14 battery, while the A9 III can take 530 images on a single charge of its Sony NP-FZ100 power pack. The power pack in the A9 III can be charged via the USB port, which can be very convenient when travelling.
The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. If you want to switch the focus of the display and review another camera pair, you can move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons there.

| Camera Model |
Camera Width |
Camera Height |
Camera Depth |
Camera Weight |
Battery Life |
Weather Sealing |
Camera Launch |
Launch Price |
Street Price |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Nikon D5100 | 128 mm | 97 mm | 79 mm | 560 g | 660 | n | Apr 2011 | US$ 749 | ebay.com | |
| 2. | Sony A9 III | 136 mm | 97 mm | 83 mm | 702 g | 530 | Y | Nov 2023 | US$ 5 999 | amazon.com | |
| 3. | Canon T2i | 129 mm | 98 mm | 62 mm | 530 g | 440 | n | Feb 2010 | US$ 699 | ebay.com | |
| 4. | Nikon D3100 | 124 mm | 96 mm | 75 mm | 505 g | 550 | n | Aug 2010 | US$ 599 | ebay.com | |
| 5. | Nikon D3200 | 125 mm | 96 mm | 77 mm | 505 g | 540 | n | Apr 2012 | US$ 599 | ebay.com | |
| 6. | Nikon D5000 | 127 mm | 104 mm | 80 mm | 590 g | 510 | n | Apr 2009 | US$ 749 | ebay.com | |
| 7. | Nikon D5200 | 129 mm | 98 mm | 78 mm | 555 g | 500 | n | Nov 2012 | US$ 749 | ebay.com | |
| 8. | Nikon D5300 | 125 mm | 98 mm | 76 mm | 480 g | 600 | n | Oct 2013 | US$ 799 | ebay.com | |
| 9. | Nikon D5500 | 124 mm | 97 mm | 70 mm | 470 g | 820 | n | Jan 2015 | US$ 899 | ebay.com | |
| 10. | Nikon D5600 | 124 mm | 97 mm | 70 mm | 465 g | 970 | n | Nov 2016 | US$ 699 | ebay.com | |
| 11. | Nikon D7000 | 132 mm | 105 mm | 77 mm | 780 g | 1050 | Y | Sep 2010 | US$ 1 499 | ebay.com | |
| 12. | Sony A1 II | 136 mm | 97 mm | 83 mm | 743 g | 520 | Y | Nov 2024 | US$ 6 499 | amazon.com | |
| 13. | Sony A7 II | 127 mm | 96 mm | 60 mm | 599 g | 350 | Y | Nov 2014 | US$ 1 999 | ebay.com | |
| 14. | Sony A7 III | 127 mm | 96 mm | 74 mm | 650 g | 610 | Y | Feb 2018 | US$ 1 999 | amazon.com | |
| 15. | Sony A9 | 127 mm | 96 mm | 63 mm | 673 g | 650 | Y | Apr 2017 | US$ 4 499 | ebay.com | |
| 16. | Sony A9 II | 129 mm | 96 mm | 76 mm | 678 g | 690 | Y | Oct 2019 | US$ 4 499 | amazon.com | |
| 17. | Sony NEX-5N | 111 mm | 59 mm | 38 mm | 269 g | 460 | n | Aug 2011 | US$ 699 | ebay.com | |
| Note: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders. | |||||||||||
Any camera decision will naturally be influenced heavily by the price. The manufacturer’s suggested retail prices give an idea on the placement of the camera in the maker’s lineup and the broader market. The D5100 was launched at a markedly lower price (by 88 percent) than the A9 III, which puts it into a different market segment. Usually, retail prices stay at first close to the launch price, but after several months, discounts become available. Later in the product cycle and, in particular, when the replacement model is about to appear, further discounting and stock clearance sales often push the camera price considerably down. Then, after the new model is out, very good deals can frequently be found on the pre-owned market.
Sensor comparison
The imaging sensor is at the core of digital cameras and its size is one of the main determining factors of image quality. A large sensor will tend to have larger individual pixels that provide better low-light sensitivity, wider dynamic range, and richer color-depth than smaller pixel-units in a sensor of the same technological generation. Furthermore, a large sensor camera will give the photographer more possibilities to use shallow depth-of-field in order to isolate a subject from the background. On the downside, larger sensors tend to be more expensive and lead to bigger and heavier cameras and lenses.
Of the two cameras under consideration, the Nikon D5100 features an APS-C sensor and the Sony A9 III a full frame sensor. The sensor area in the A9 III is 128 percent bigger. As a result of these sensor size differences, the cameras have a format factor of, respectively, 1.5 and 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

With 24MP, the A9 III offers a higher resolution than the D5100 (16.1MP), but the A9 III nevertheless has larger individual pixels (pixel pitch of 5.94μm versus 4.80μm for the D5100) due to its larger sensor. Moreover, the A9 III is a much more recent model (by 12 years and 7 months) than the D5100, and its sensor will have benefitted from technological advances during this time that further enhance the light gathering capacity of its pixel-units.
The resolution advantage of the Sony A9 III implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the A9 III for good quality output (200 dots per inch) amounts to 30 x 20 inches or 76.2 x 50.8 cm, for very good quality (250 dpi) 24 x 16 inches or 61 x 40.6 cm, and for excellent quality (300 dpi) 20 x 13.3 inches or 50.8 x 33.9 cm. The corresponding values for the Nikon D5100 are 24.6 x 16.3 inches or 62.6 x 41.5 cm for good quality, 19.7 x 13.1 inches or 50.1 x 33.2 cm for very good quality, and 16.4 x 10.9 inches or 41.7 x 27.6 cm for excellent quality prints.
The A9 III has on-sensor phase detect pixels, which results in fast and reliable autofocus acquisition even during live view operation.
The Nikon D5100 has a native sensitivity range from ISO 100 to ISO 6400, which can be extended to ISO 100-25600. The corresponding ISO settings for the Sony Alpha A9 III are ISO 250 to ISO 25600, with the possibility to increase the ISO range to 125-51200.
In terms of underlying technology, the D5100 is build around a CMOS sensor, while the A9 III uses a Stacked CMOS imager. Both cameras use a Bayer filter for capturing RGB colors on a square grid of photosensors. This arrangement is found in most digital cameras.

For many cameras, data on sensor performance has been reported by DXO Mark. This service determines an overall sensor rating, as well as sub-scores for low-light sensitivity ("DXO Sports"), dynamic range ("DXO Landscape"), and color depth ("DXO Portrait"). The table below summarizes the physical sensor characteristics and sensor quality findings and compares them across a set of similar cameras.

| Camera Model |
Sensor Class |
Resolution (MP) |
Horiz. Pixels |
Vert. Pixels |
Video Format |
DXO Portrait |
DXO Landscape |
DXO Sports |
DXO Overall |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Nikon D5100 | APS-C | 16.1 | 4928 | 3264 | 1080/30p | 23.5 | 13.6 | 1183 | 80 | |
| 2. | Sony A9 III | Full Frame | 24.0 | 6000 | 4000 | 4K/120p | 25.4 | 14.7 | 3243 | 96 | |
| 3. | Canon T2i | APS-C | 17.9 | 5184 | 3456 | 1080/30p | 22.1 | 11.5 | 784 | 66 | |
| 4. | Nikon D3100 | APS-C | 14.2 | 4608 | 3072 | 1080/24p | 22.5 | 11.3 | 919 | 67 | |
| 5. | Nikon D3200 | APS-C | 24.1 | 6016 | 4000 | 1080/30p | 24.1 | 13.2 | 1131 | 81 | |
| 6. | Nikon D5000 | APS-C | 12.2 | 4288 | 2848 | 720/24p | 22.7 | 12.5 | 868 | 72 | |
| 7. | Nikon D5200 | APS-C | 24.0 | 6000 | 4000 | 1080/60i | 24.2 | 13.9 | 1284 | 84 | |
| 8. | Nikon D5300 | APS-C | 24.0 | 6000 | 4000 | 1080/60p | 24.0 | 13.9 | 1338 | 83 | |
| 9. | Nikon D5500 | APS-C | 24.0 | 6000 | 4000 | 1080/60p | 24.1 | 14.0 | 1438 | 84 | |
| 10. | Nikon D5600 | APS-C | 24.0 | 6000 | 4000 | 1080/60p | 24.1 | 14.0 | 1306 | 84 | |
| 11. | Nikon D7000 | APS-C | 16.1 | 4928 | 3264 | 1080/24p | 23.5 | 13.9 | 1167 | 80 | |
| 12. | Sony A1 II | Full Frame | 49.8 | 8640 | 5760 | 8k/30p | 25.4 | 14.8 | 3363 | 97 | |
| 13. | Sony A7 II | Full Frame | 24.0 | 6000 | 4000 | 1080/60p | 24.9 | 13.6 | 2449 | 90 | |
| 14. | Sony A7 III | Full Frame | 24.0 | 6000 | 4000 | 4K/30p | 25.0 | 14.7 | 3730 | 96 | |
| 15. | Sony A9 | Full Frame | 24.0 | 6000 | 4000 | 4K/30p | 24.9 | 13.3 | 3517 | 92 | |
| 16. | Sony A9 II | Full Frame | 24.0 | 6000 | 4000 | 4K/30p | 25.0 | 14.0 | 3434 | 93 | |
| 17. | Sony NEX-5N | APS-C | 16.0 | 4912 | 3264 | 1080/60i | 23.6 | 12.7 | 1079 | 77 | |
| Note: DXO values in italics represent estimates based on sensor size and age. | |||||||||||
Many modern cameras are not only capable of taking still images, but also of capturing video footage. The two cameras under consideration both have sensors whose read-out speed is fast enough to capture moving pictures, but the A9 III provides a better video resolution than the D5100. It can shoot movie footage at 4K/120p, while the Nikon is limited to 1080/30p.
Feature comparison
Apart from body and sensor, cameras can and do differ across a variety of features. For example, the A9 III has an electronic viewfinder (9440k dots), while the D5100 has an optical one. Both systems have their advantages, with the electronic viewfinder making it possible to project supplementary shooting information into the framing view, whereas the optical viewfinder offers lag-free viewing and a very clear framing image. The viewfinder in the A9 III offers a wider field of view (100%) than the one in the D5100 (95%), so that a larger proportion of the captured image is visible in the finder. In addition, the viewfinder of the A9 III has a higher magnification (0.9x vs 0.51x), so that the size of the image transmitted appears closer to the size seen with the naked human eye. The adjacent table lists some of the other core features of the Nikon D5100 and Sony A9 III along with similar information for a selection of comparators.

| Camera Model |
Viewfinder (Type or 000 dots) |
Control Panel (yes/no) |
LCD Specifications (inch/000 dots) |
LCD Attach- ment |
Touch Screen (yes/no) |
Max Shutter Speed * |
Max Shutter Flaps * |
Built-in Flash (yes/no) |
Built-in Image Stab |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Nikon D5100 | optical | n | 3.0 / 921 | swivel | n | 1/4000s | 4.0/s | Y | n | |
| 2. | Sony A9 III | 9440 | n | 3.2 / 2100 | full-flex | Y | 1/80000s | 120.0/s | n | Y | |
| 3. | Canon T2i | optical | n | 3.0 / 1040 | fixed | n | 1/4000s | 3.7/s | Y | n | |
| 4. | Nikon D3100 | optical | n | 3.0 / 230 | fixed | n | 1/4000s | 3.0/s | Y | n | |
| 5. | Nikon D3200 | optical | n | 3.0 / 921 | fixed | n | 1/4000s | 4.0/s | Y | n | |
| 6. | Nikon D5000 | optical | n | 2.7 / 230 | full-flex | n | 1/4000s | 4.0/s | Y | n | |
| 7. | Nikon D5200 | optical | n | 3.0 / 921 | swivel | n | 1/4000s | 5.0/s | Y | n | |
| 8. | Nikon D5300 | optical | n | 3.2 / 1037 | swivel | n | 1/4000s | 5.0/s | Y | n | |
| 9. | Nikon D5500 | optical | n | 3.2 / 1037 | swivel | Y | 1/4000s | 5.0/s | Y | n | |
| 10. | Nikon D5600 | optical | n | 3.2 / 1037 | swivel | Y | 1/4000s | 5.0/s | Y | n | |
| 11. | Nikon D7000 | optical | Y | 3.0 / 921 | fixed | n | 1/8000s | 6.0/s | Y | n | |
| 12. | Sony A1 II | 9437 | n | 3.2 / 2100 | full-flex | Y | 1/8000s | 30.0/s | n | Y | |
| 13. | Sony A7 II | 2400 | n | 3.0 / 1230 | tilting | n | 1/8000s | 5.0/s | n | Y | |
| 14. | Sony A7 III | 2359 | n | 3.0 / 922 | tilting | Y | 1/8000s | 10.0/s | n | Y | |
| 15. | Sony A9 | 3686 | n | 3.0 / 1440 | tilting | Y | 1/8000s | 20.0/s | n | Y | |
| 16. | Sony A9 II | 3686 | n | 3.0 / 1440 | tilting | Y | 1/8000s | 20.0/s | n | Y | |
| 17. | Sony NEX-5N | optional | n | 3.0 / 920 | tilting | Y | 1/4000s | 10.0/s | n | n | |
| Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one. | |||||||||||
One difference between the cameras concerns the presence of an on-board flash. The D5100 has one, while the A9 III does not. While the built-in flash of the D5100 is not very powerful, it can at times be useful as a fill-in light.
Both cameras have an articulated rear screen that can be turned to be front-facing. This feature will be particularly appreciated by vloggers and photographers who are interested in taking selfies.The reported shutter speed information refers to the use of the mechanical shutter. Yet, some cameras only have an electronic shutter, while others have an electronic shutter in addition to a mechanical one. In fact, the A9 III is one of those camera that have an additional electronic shutter, which makes completely silent shooting possible. However, this mode is less suitable for photographing moving objects (risk of rolling shutter) or shooting under artificial light sources (risk of flickering).
The Nikon D5100 and the Sony A9 III both have an intervalometer built-in. This enables the photographer to capture time lapse sequences, such as flower blooming, a sunset or moon rise, without purchasing an external camera trigger and related software.
The D5100 writes its imaging data to SDXC cards, while the A9 III uses CFexpress (type A) or SDXC cards. The A9 III features dual card slots, which can be very useful in case a memory card fails. In contrast, the D5100 only has one slot. The A9 III supports UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s), while the D5100 can use UHS-I cards (up to 104 MB/s).
Connectivity comparison
For some imaging applications, the extent to which a camera can communicate with its environment can be an important aspect in the camera decision process. The table below provides an overview of the connectivity of the Nikon D5100 and Sony Alpha A9 III and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.

| Camera Model |
Hotshoe Port |
Internal Mic / Speaker |
Microphone Port |
Headphone Port |
HDMI Port |
USB Port |
WiFi Support |
NFC Support |
Bluetooth Support |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Nikon D5100 | Y | mono / mono | Y | - | mini | 2.0 | - | - | - | |
| 2. | Sony A9 III | Y | stereo / mono | Y | Y | full | 3.2 | Y | - | Y | |
| 3. | Canon T2i | Y | stereo / - | Y | - | mini | 2.0 | - | - | - | |
| 4. | Nikon D3100 | Y | mono / mono | - | - | mini | 2.0 | - | - | - | |
| 5. | Nikon D3200 | Y | mono / mono | Y | - | mini | 2.0 | - | - | - | |
| 6. | Nikon D5000 | Y | mono / mono | - | - | mini | 2.0 | - | - | - | |
| 7. | Nikon D5200 | Y | stereo / mono | Y | - | mini | 2.0 | - | - | - | |
| 8. | Nikon D5300 | Y | stereo / mono | Y | - | mini | 2.0 | Y | - | - | |
| 9. | Nikon D5500 | Y | stereo / mono | Y | - | mini | 2.0 | Y | - | - | |
| 10. | Nikon D5600 | Y | stereo / mono | Y | - | mini | 2.0 | Y | Y | Y | |
| 11. | Nikon D7000 | Y | mono / mono | Y | - | mini | 2.0 | - | - | - | |
| 12. | Sony A1 II | Y | stereo / mono | Y | Y | full | 3.2 | Y | - | Y | |
| 13. | Sony A7 II | Y | stereo / mono | Y | Y | micro | 2.0 | Y | Y | - | |
| 14. | Sony A7 III | Y | stereo / mono | Y | Y | micro | 3.1 | Y | Y | Y | |
| 15. | Sony A9 | Y | stereo / mono | Y | Y | micro | 2.0 | Y | Y | Y | |
| 16. | Sony A9 II | Y | stereo / mono | Y | Y | micro | 3.1 | Y | Y | Y | |
| 17. | Sony NEX-5N | Y | stereo / mono | - | - | mini | 2.0 | - | - | - |
It is notable that the A9 III offers wifi support, which can be a very convenient means to transfer image data to an off-camera location. In contrast, the D5100 does not provide wifi capability.
Studio photographers will appreciate that the Sony A9 III (unlike the D5100) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.
The A9 III is a recent model that features in the current product line-up of Sony. In contrast, the D5100 has been discontinued (but can be found pre-owned on ebay). As a replacement in the same line of cameras, the D5100 was succeeded by the Nikon D5200. Further information on the features and operation of the D5100 and A9 III can be found, respectively, in the Nikon D5100 Manual (free pdf) or the online Sony A9 III Manual.
Review summary
So what is the bottom line? Is the Nikon D5100 better than the Sony A9 III or vice versa? Below is a summary of the relative strengths of each of the two contestants.

Arguments in favor of the Nikon D5100:
- Brighter framing: Features an optical viewfinder for clear, lag-free composition.
- Less heavy: Is lighter (by 142g or 20 percent) and hence easier to carry around.
- Longer lasting: Can take more shots (660 versus 530) on a single battery charge.
- Easier fill-in: Is equipped with a small onboard flash to brighten deep shadow areas.
- More affordable: Was introduced into a lower priced category (88 percent cheaper at launch).
- More heavily discounted: Has been available for much longer (launched in April 2011).

Advantages of the Sony Alpha A9 III:
- More detail: Has more megapixels (24 vs 16.1MP), which boosts linear resolution by 22%.
- Better image quality: Is equipped with a larger and more technologically advanced sensor.
- Richer colors: The sensor size advantage translates into images with better, more accurate colors.
- More dynamic range: Larger sensor captures a wider spectrum of light and dark details.
- Better low-light sensitivity: Larger sensor produces good images even in poorly lit environments.
- Better video: Provides higher definition movie capture (4K/120p vs 1080/30p).
- Better live-view autofocus: Features on-sensor phase-detection for more confident autofocus.
- Better sound control: Has a headphone port that enables audio monitoring while recording.
- More framing info: Has an electronic viewfinder that displays shooting data.
- More complete view: Has a viewfinder with a larger field of view (100% vs 95%).
- Larger viewfinder image: Features a viewfinder with a higher magnification (0.9x vs 0.51x).
- Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
- More detailed LCD: Has a higher resolution rear screen (2100k vs 921k dots).
- Fewer buttons to press: Has a touchscreen to facilitate handling and shooting adjustments.
- Faster shutter: Has higher mechanical shutter speed (1/80000s vs 1/4000s) to freeze action.
- Faster burst: Shoots at higher frequency (120 vs 4 flaps/sec) to capture the decisive moment.
- Less disturbing: Has an electronic shutter option for completely silent shooting.
- Easier travel charging: Can be conveniently charged via its USB port.
- Better sealing: Is splash and dust sealed for shooting in inclement weather conditions.
- Sharper images: Has stabilization technology built-in to reduce the impact of hand-shake.
- More legacy lens friendly: Can use many non-native lenses via adapters.
- Faster data transfer: Supports a more advanced USB protocol (3.2 vs 2.0).
- Easier file upload: Has wifi built in for automatic backup or image transfer to the web.
- Easier wireless transfer: Supports Bluetooth for image sharing without cables.
- Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
- Greater peace of mind: Features a second card slot as a backup in case of memory card failure.
- Faster buffer clearing: Supports a more advanced SD data transfer standard (UHS-II vs UHS-I).
- More modern: Reflects 12 years and 7 months of technical progress since the D5100 launch.
If the number of relative strengths (bullet points above) is taken as a guide, the A9 III is the clear winner of the contest (29 : 6 points). However, the relevance of individual strengths will vary across photographers, so that you might want to apply your own weighing scheme to the summary points when reflecting and deciding on a new camera. A professional wildlife photographer will view the differences between cameras in a way that diverges from the perspective of a family photog, and a person interested in architecture has distinct needs from a sports shooter. Hence, the decision which camera is best and worth buying is often a very personal one.
How about other alternatives? Do the specifications of the Nikon D5100 and the Sony A9 III place the cameras among the top in their class? Find out in the latest Best DSLR Camera and Best Mirrorless Interchangeable Lens Camera listings whether the two cameras rank among the cream of the crop.
In any case, while the specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it remains incomplete and does no justice, for example, to the way the D5100 or the A9 III perform in practice. User reviews that are available, for instance, at amazon can sometimes shed light on these issues, but such feedback is all too often partial, inconsistent, and inaccurate.
Expert reviews
This is why expert reviews are important. The adjacent summary-table relays the overall verdicts of several of the most popular camera review sites (amateurphotographer [AP], cameralabs [CL], digitalcameraworld [DCW], dpreview [DPR], ephotozine [EPZ], photographyblog [PB]). As can be seen, the professional reviewers agree in many cases on the quality of different cameras, but sometimes their assessments diverge, reinforcing the earlier point that a camera decision is often a very personal choice.

| Camera Model |
AP score |
CL score |
DCW score |
DPR score |
EPZ score |
PB score |
Camera Launch |
Launch Price |
Street Price |
||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1. | Nikon D5100 | 5/5 | + + | .. | 76/100 | 4.5/5 | 4.5/5 | Apr 2011 | US$ 749 | ebay.com | |
| 2. | Sony A9 III | 4.5/5 | .. | .. | 91/100 | .. | .. | Nov 2023 | US$ 5 999 | amazon.com | |
| 3. | Canon T2i | .. | + + | .. | 77/100 | 4/5 | 4.5/5 | Feb 2010 | US$ 699 | ebay.com | |
| 4. | Nikon D3100 | 5/5 | + + | .. | 72/100 | 4.5/5 | 4.5/5 | Aug 2010 | US$ 599 | ebay.com | |
| 5. | Nikon D3200 | 5/5 | + + | .. | 73/100 | 4.5/5 | 4.5/5 | Apr 2012 | US$ 599 | ebay.com | |
| 6. | Nikon D5000 | .. | + + | .. | 75/100 | 4/5 | 4.5/5 | Apr 2009 | US$ 749 | ebay.com | |
| 7. | Nikon D5200 | 4/5 | + + | .. | 79/100 | 4.5/5 | 4.5/5 | Nov 2012 | US$ 749 | ebay.com | |
| 8. | Nikon D5300 | 4/5 | + + | .. | 79/100 | 4.5/5 | 4.5/5 | Oct 2013 | US$ 799 | ebay.com | |
| 9. | Nikon D5500 | 5/5 | + | .. | 79/100 | 4.5/5 | 4.5/5 | Jan 2015 | US$ 899 | ebay.com | |
| 10. | Nikon D5600 | 4/5 | .. | 4/5 | 79/100 | 4.5/5 | 4/5 | Nov 2016 | US$ 699 | ebay.com | |
| 11. | Nikon D7000 | 4/5 | .. | .. | 80/100 | 4.5/5 | 4.5/5 | Sep 2010 | US$ 1 499 | ebay.com | |
| 12. | Sony A1 II | .. | .. | .. | .. | .. | .. | Nov 2024 | US$ 6 499 | amazon.com | |
| 13. | Sony A7 II | 5/5 | + | 4/5 | 82/100 | 4.5/5 | 5/5 | Nov 2014 | US$ 1 999 | ebay.com | |
| 14. | Sony A7 III | .. | + + | 4.5/5 | 89/100 | 5/5 | 5/5 | Feb 2018 | US$ 1 999 | amazon.com | |
| 15. | Sony A9 | 5/5 | + + | 4.8/5 | 89/100 | 5/5 | 5/5 | Apr 2017 | US$ 4 499 | ebay.com | |
| 16. | Sony A9 II | .. | .. | 5/5 | 90/100 | 5/5 | 5/5 | Oct 2019 | US$ 4 499 | amazon.com | |
| 17. | Sony NEX-5N | 3/5 | + + | .. | 79/100 | 4.5/5 | 4.5/5 | Aug 2011 | US$ 699 | ebay.com | |
| Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available. | |||||||||||
The review scores listed above should be treated with care, though. The ratings were established in reference to similarly priced cameras that were available in the market at the time of the review. A score, therefore, has to be seen in close connection to the price and market introduction time of the camera, and comparing ratings of very distinct cameras or ones that are far apart in terms of their release date have little meaning. Also, please note that some of the review sites have changed their methodology and reporting over time.

Check D5100 offers at
ebay.com

Check A9 III price at
amazon.com
Other camera comparisons
Did this review help to inform your camera decision process? If you would like to see a different side-by-side camera review, just make a corresponding selection in the search boxes below. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.
- Canon R6 vs Sony A9 III
- Canon S120 vs Sony A9 III
- Canon SX10 vs Sony A9 III
- Canon SX520 vs Nikon D5100
- Canon SX740 vs Sony A9 III
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- Nikon D5100 vs Olympus E-M5 II
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Specifications: Nikon D5100 vs Sony A9 III
Below is a side-by-side comparison of the specs of the two cameras to facilitate a quick review of their differences and common features.
| Camera Model | Nikon D5100 | Sony A9 III |
|---|---|---|
| Camera Type | Digital single lens reflex | Mirrorless system camera |
| Camera Lens | Nikon F mount lenses | Sony E mount lenses |
| Launch Date | April 2011 | November 2023 |
| Launch Price | USD 749 | USD 5,999 |
| Sensor Specs | Nikon D5100 | Sony A9 III |
| Sensor Technology | CMOS | Stacked CMOS |
| Sensor Format | APS-C Sensor | Full Frame Sensor |
| Sensor Size | 23.6 x 15.7 mm | 35.6 x 23.8 mm |
| Sensor Area | 370.52 mm2 | 847.28 mm2 |
| Sensor Diagonal | 28.3 mm | 42.8 mm |
| Crop Factor | 1.5x | 1.0x |
| Sensor Resolution | 16.1 Megapixels | 24 Megapixels |
| Image Resolution | 4928 x 3264 pixels | 6000 x 4000 pixels |
| Pixel Pitch | 4.80 μm | 5.94 μm |
| Pixel Density | 4.34 MP/cm2 | 2.83 MP/cm2 |
| Moiré control | Anti-Alias filter | Anti-Alias filter |
| Movie Capability | 1080/30p Video | 4K/120p Video |
| ISO Setting | 100 - 6,400 ISO | 250 - 25,600 ISO |
| ISO Boost | 100 - 25,600 ISO | 125 - 51,200 ISO |
| Image Processor | EXPEED 2 | Dual BIONZ XR |
| DXO Sensor Quality (score) | 80 | .. |
| DXO Color Depth (bits) | 23.5 | .. |
| DXO Dynamic Range (EV) | 13.6 | .. |
| DXO Low Light (ISO) | 1183 | .. |
| Screen Specs | Nikon D5100 | Sony A9 III |
| Viewfinder Type | Optical viewfinder | Electronic viewfinder |
| Viewfinder Field of View | 95% | 100% |
| Viewfinder Magnification | 0.51x | 0.9x |
| Viewfinder Resolution | 9440k dots | |
| LCD Framing | Live View | Live View |
| Rear LCD Size | 3.0inch | 3.2inch |
| LCD Resolution | 921k dots | 2100k dots |
| LCD Attachment | Swivel screen | Fully flexible screen |
| Touch Input | no Touchscreen | Touchscreen |
| Shooting Specs | Nikon D5100 | Sony A9 III |
| Focus System | Phase-detect AF | On-Sensor Phase-detect |
| Manual Focusing Aid | no Peaking Feature | Focus Peaking |
| Max Shutter Speed (mechanical) | 1/4000s | 1/80000s |
| Continuous Shooting | 4 shutter flaps/s | 120 shutter flaps/s |
| Electronic Shutter | no E-Shutter | up to 1/80000s |
| Time-Lapse Photography | Intervalometer built-in | Intervalometer built-in |
| Image Stabilization | Lens stabilization only | In-body stabilization |
| Fill Flash | Built-in Flash | no On-Board Flash |
| Storage Medium | SDXC cards | CFexA or SDXC cards |
| Single or Dual Card Slots | Single card slot | Dual card slots |
| UHS card support | UHS-I | UHS-II |
| Connectivity Specs | Nikon D5100 | Sony A9 III |
| External Flash | Hotshoe | Hotshoe |
| Studio Flash | no PC Sync | PC Sync socket |
| USB Connector | USB 2.0 | USB 3.2 |
| HDMI Port | mini HDMI | full HDMI |
| Microphone Port | External MIC port | External MIC port |
| Headphone Socket | no Headphone port | Headphone port |
| Wifi Support | no Wifi | Wifi built-in |
| Bluetooth Support | no Bluetooth | Bluetooth built-in |
| Body Specs | Nikon D5100 | Sony A9 III |
| Environmental Sealing | not weather sealed | Weathersealed body |
| Battery Type | Nikon EN-EL14 | Sony NP-FZ100 |
| Battery Life (CIPA) | 660 shots per charge | 530 shots per charge |
| In-Camera Charging | no USB charging | USB charging |
| Body Dimensions |
128 x 97 x 79 mm (5.0 x 3.8 x 3.1 in) |
136 x 97 x 83 mm (5.4 x 3.8 x 3.3 in) |
| Camera Weight | 560 g (19.8 oz) | 702 g (24.8 oz) |

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