Head to Head: Sony a7III vs. Nikon D850
Can the mirrorless A7III stack up to a king of DSLRs?
Let's get the obvious out of the way: The Sony A7III is still new to me. This is not an in-depth review. What I intend for this to be is more like a reactionary storytelling of my first few experiences with the camera in the field. No, these cameras are not direct competitors in their lineups. The D850 is designed for serious landscape photography work, but is a general powerhouse for just about every other use. The Sony A7III was definitely not designed to compete with that; that's what the A7R series is for.
This is me, finally jumping aboard the mirrorless ship, seeing what Sony has to offer now that they are many iterations into making full frame mirrorless cameras, and so far, I like what I'm seeing.
I recently came into an opportunity to buy this practically brand new A7III with a Sony 35mm f/2.8 and the Sony 85mm f/1.8 (plus a battery grip and two extra batteries) together for a really great price from a close friend. He put literally less than 100 shots on the body, so I grabbed it up and have already taken it out for a couple nights of shooting astro. Let me preface the rest of this by saying that I'm not a professional reviewer. If I don't cover all the bases or if I make some assumptions that don't line up with other people's experiences - that's just because this is the first time I'm able to compare two cameras of this caliber and they happen to be from two entirely different systems. This is also my first time putting to words what my experience is like - comparing two pieces of equipment side-by-side like this.
So now, let's dig in.
Battery life is important to me. When I first got into photography, I couldn't imagine that I'd one day be needing batteries that could allow me to shoot a couple thousand images before needing to swap for a new one, but here I am shooting numerous weddings a year, doing long-running timelapses, and spending weekends in the woods capturing all manner of subjects. I need a camera that can go the distance and I found that in both the Nikon D500, and more recently the Nikon D850. I purchased my D850 at the end of summer in 2020. I used it for a couple weddings, took it on many trips for fall color landscape photography, and have lately been giving it a good run for its money with wildlife photography between the ducks, bald eagles, and swans that inhabit a riverside park not far from my home. I've never felt the battery life to be less than exceptional in this camera.
To put this plainly, the Sony A7III has blown me away. I just hoped that the A7III would match the battery life I enjoyed out of the Nikon DSLR system, but what I've found so far is consistent performance that indicates battery life is far better on the A7III than the D850. Let me break down my experiences.
On the first night I took the cameras out together, a 2-hour period on March 9th, I noted down what I thought was an anomaly. When my Nikon D850 was roughly at 50% battery left, the Sony was still near 80% and I couldn't believe it. I used both cameras side-by-side for roughly two hours straight, shooting long exposures of the stars. It was blistering cold, nearing 10 degrees with the constant winds, so faster battery drain was to be expected.
I went home scratching my head wondering why a mirrorless camera would hold it's battery life more efficiently than a DSLR. There's no EVF on a DSLR. I used live-view far less frequently, and the Sony camera has more electronic workings going on than the Nikon does, including stabilization and focus assistance. It just didn't add up, but here's the thing; that's consistently been the case now, on warmer nights and much longer sessions.
The D850 battery is, in fact, the EN-EL15a battery, designed to best perform on the D850, as opposed to using older versions of the EN-EL15, so that wasn't an issue. The A7III was also at a disadvantage because it basically is using live-view all the time as opposed to the Nikon only having live view on when I needed to re-check focus or check my internal level relative to my composition. I'm sure I can make changes to the behavior of live-view on the Sony, but as it sits now, it only turns off/goes into a sleep state after a one minute period of being left alone. Not only that, but I have the display quality set to high, which may also affect battery life on the Sony. Despite all that, it performed better. Perhaps it's because the D850 is pushing out almost twice the resolution in every image - that may have something to do with it.
On my next night out, I spent six hours shooting the northern lights at the same area, but with temperatures closer to 40 degrees on that night. After 4 hours, the Nikon D850 battery was drained to less than 5%, which is the point at which I turned the camera off and swapped in for another battery. At this time, the Sony A7III still had 68% of its battery left and I couldn't have been more impressed. I even went on to shoot with the Sony for another hour and by the time sunrise came around, I still hadn't drained the Sony battery to 50%.
The A7III absolutely dominated the D850 in the battery life category and I now know that the stigma placed on mirrorless cameras for having poor battery life is a thing of the past.
So What's It Like In The Field?
As different as these cameras may be, specifically for astrophotography and shooting at night where it's difficult to see what you're doing without a light on, the Nikon D850 is the winner in my mind with its bigger, spaced out, illuminating buttons. Once I actually get familiar with all the menus and command locations for the relevant settings for astro, I'm sure the Sony will be just as easy to use as the Nikon for me, but the D850 buttons lighting up really do help. I'm sure I'll end up writing a long term review of this A7III, so I'm not going to knock any points for me not being familiar with the setting locations yet, so I'll hold most of that judgement for a later time, but if I was to grab one of these two cameras and rush out of the house, I'd grab the Nikon if for no other reason than to have those illuminating buttons, eliminating any errors in the dark.
Outside of astro, the experience on the Sony is not dissatisfying. IBIS makes any lens stabilized, which is an amazing thing to experience for the first time, especially while using all-manual adapted lenses. I look forward to taking advantage of that in the future.
Additionally, the A7III is considerably lighter in weight. After long hikes, the D850 (1015g) with, say, the Sigma 50mm 1.4 art lens can really put a strain on my neck with it hanging from the strap most of the day. On my first hike out with the Sony, I pushed through icy and muddy terrain for almost 3 hours with the 85mm 1.8 mounted on the A7III (650g) and it was a breeze.
To talk about buttons once more, I feel the size of the buttons on the A7III are a bit too small for me. I don't have super large hands, and the camera itself isn't too small to grip it well, but each of the smaller round buttons could stand to be a little bigger. Specifically, I really think the AF-ON button needs to be spaced away from the video record button a bit more and the video record button needs to move away from the EVF a few millimeters. Trying to fit my finger overtop the video record button results in my fingertip getting pressed against the outside of the EVF and that's not too comfortable, no matter how infrequently I may need to hit that button. The AF-ON button could also benefit from extruding out just a tad more for a more tactile feel. Sometimes I'll hit that button and not feel confident that I actually pressed in hard enough to activate it. If that button just stuck out a tad bit more, that would ease my mind while I'm trying to focus through the EVF. That's pretty picky stuff, so consider that I had no other major issues complaints to be a good thing about the cameras design and user experience.
The menu layout seems fine. I hear Sony catch a lot of flak for bad menu design, but this is just one of those things that when you learn it, that's it. It's no longer an issue.
The Nikon system isn't exactly perfect. While the D850 is bigger and heavier, that allows more room for considerate button design. Everything feels super tactile on this camera, so if I'm shooting at night, I don't have to question whether I actually pressed a button down hard enough. Alright, that's enough about buttons.
Let's talk about EVF vs OVF
Back in 2012 I purchased my first camera, the Sony a55, and then a year later I purchased the Sony a65. My first two cameras both had electronic viewfinders and I really enjoyed the benefits of them. Being able to see what my settings would do to the image I was about to take before I hit that shutter button was really cool. I actually believe it's a good way to learn how certain settings affect your exposure. Watching the exposure change in real time through an EVF as you spin your aperture or shutter speed dials takes a lot of guesswork out of the equation very quickly.
In 2015, I purchased the Nikon D5300 - my first body with an optical viewfinder, which lacks all the benefits an electronic viewfinder gives. But guess what? Using cameras with an EVF for three years had given me all the time I needed to learn how to make a proper exposure because I spent three years watching exactly how each setting changed my exposure. When I got my Nikon, I had absolutely no issue transitioning to an optical viewfinder. I used Live-View when I needed to see my composition on-screen beforehand, but I found an OVF to be perfectly good. It felt real, natural, organic - whatever you want to call it; an OVF is just easy and comfortable.
Now, before you read too far into my opinion of the EVF implementation on the A7III, just remember this is a first-impression comparison, so I'm going to eventually learn to be more comfortable with this, but I do not miss using an EVF one bit after being away from it for 6 years. Sony has made great strides in allowing the EVF to be really functional. You can enable both zebra stripes and focus peaking with customizations for them inside the EVF, which can be really handy, especially for recording video if you needed that. There's a lot to like about an EVF in general, but I just didn't miss it and using it on the A7III doesn't make me feel like it's helping me any now that I know exactly what to expect for every change in my exposure settings. I can still tell I'm looking at a digital display, rather than looking through glass at the actual scene. This just boils down to personal preference and what I've been using most of my shooting career, but I can now understand why so many old school pros have held onto their DSLRs with some of them refusing to transition to mirrorless.
Again, give me a year and I'll probably come to love it once again.
Reviewing the Files
On my few nights out with both cameras, I've now had time to really shoot them side by side. Let me break down my setups.
On the D850 I mounted the Sigma 20mm f/1.4 Art lens. This is a magnificent lens for collecting lots of light for landscape astrophotography, but isn't without its faults. The lens opened to f/1.4 suffers from moderate distortion in the stars in the corners of the image. This is a common quality among wider lenses in general, but especially so at such a fast aperture. When stopped down to, say, 1.8 or higher, the corners tighten up considerably.
On the A7III, I adapted my Samyang 24mm f/1.4 lens with an Urth brand manual-only adapter. For a lens that's only got manual aperture control anyway, this was just fine. And yes, I'll acknowledge that these two lenses are on entirely different quality levels. The sigma is twice the price of the Samyang, but what I'm more interested in, is how the files from these cameras hold up with regard to noise profiles and shadow recovery, more than technical sharpness necessarily.
At a difference of 4 millimeters in focal length, I made sure to only use shutter speeds that both could achieve without star trailing characteristics showing up and did choose to keep both lenses wide open at f/1.4 to keep it fair and simple. I expect in the future I will continue comparing the two at higher apertures to see how well both hold up at different settings.
So how did it go?
The A7III held up wonderfully. The D850 uses a BSI sensor developed by Sony, and while it delivers almost twice the resolution as the A7III, they were both incredibly similar performers with high-ISO at night.
Let me show some examples. On my second night out, I had the pleasure of shooting for six hours from 2am until sunrise as the northern lights danced in the sky; a convenient event for my testing session.
For the purposes of posting to social media, or generally viewing the images on a backlit screen, they both look quite good. Both of these are edited images that got exactly the same edits synced together with the exception of temperature and tint shifts.
Both these images were shot at ISO 12,800 with a 4 second exposure wide open at f/1.4
Zooming way in, you can spot plenty of lens characteristics on the stars that would be remedied by stopping down a bit, but looking at the noise profile on both, remembering the edits are exactly the same, the A7III seems to hold up slightly better. But that's to be expected if for no other reason than because the D850 has nearly twice the resolution. The pixel pitch on the A7III is bigger, which tends to result in better noise performance all other things being equal and I think that's what we're seeing here. This is an extremely close look; I'm talking 100-200% zoom. This isn't how anyone else would actually look at these images, so considering that, side-by-side, the image quality of these two shots is far too close to say one is better than the other, which could be considered a win for the Sony given the price different of the two bodies.
The first image, the Sony, the second, the Nikon.
Let's look at another set of images.
This time, I'll show you two RAW files. On the same night, I turned to the south and captured some images of the Milky Way as it can be seen at about 4am now that it's March.
These are completely unedited exported JPEGS so you can see just what I see when I go in to look at the differences. One thing to note is that for whatever reason, I had sporadic difficulties focusing correctly on stars with the A7III. That's just another thing that will iron out over time, but other than the very slight missed focus, again we're looking at extremely similar files with regards to noise profiles. Both these images were shot with 15 second exposures at ISO 6400, wide open at f/1.4. Again, the Sony on top, and the Nikon after that. Disregard color temperatures differences - for some reason they seemed to differ a bit even though they were both set to the same custom color temperature in camera, but these are easily tweaked while editing RAW files.
Here's one more set of edited images (synced settings) just for good measure. and just to be clear, no lens corrections have been applied to any of these images for the sake of comparison.
Settings: 2" - ISO 8000 - f/1.4
I did notice that on the back of the screen on the Sony, images tend to appear much more contrasty in playback than they do on the D850, but it was just a difference in the display quality because when I got all the files together back at the office, on the same screen the raw files look much more similar than they did in the field.
Shadow recovery is excellent on both. I'll have to do more testing for a good understanding of the real dynamic range on the A7III, but there were points during this night where I really did get close to clipping highlights in the aurora, so recovering the highlights worked just as fine with the Sony as on the Nikon, but this will be better tested for sessions with lots of daylight and strong shadows in one composition.
As a bonus, lets stretch some data and see what we might determine from pulling some sliders around. Take a look:
The highlighted image on the left is the Sony and the right is the Nikon. Sorry if this was a bit hard to follow, but I wanted to have a look at just what kind of dynamic range these files had, given we have deep shadows to pull. The first thing to notice was that the simple shadow recovery slider had less impact at +100 on the Sony than the Nikon, and the same can be seen when I pull the highlights up as well. The Nikon D850 seems to have access to more range of data in the RAW files as evidenced on screen and on the histogram. Check out the histogram difference when I flip back and forth after upping the shadow slider on both. You can see the Nikon file has significantly more data further right on the histogram compared to the Sony - where you can see more of that file's data touching the left side. This is all far from scientific analysis, but it is real-world application when I find myself doing this kind of work as frequently as I do.
I will note that it appeared to me that the Nikon file had more apparent, harsher noise that got worse the more I stretched the shadows. Comparing the recovered shadow areas of the two showed that the Sony had cleaner recovered shadows, which again, could be mostly the result of the resolution difference, but it was worth noting for my own reference. I'll be interested in comparing this again with low ISO files and seeing if I can spot similar differences and consistent behaviors with dynamic range.
All in all, the Sony files appear to give a fantastic amount of latitude given I'm comparing the files to a camera that retailed for almost twice its price. Remembering just what kind of difficulties with noise and dynamic range I had way back on the a55 and a65, I can confidently say that Sony has made incredible strides to compete in the full frame camera space. I would love to get my hands on something like the A7RIV some day to do some similar comparisons because I find this all fascinating, being the nerd I am.
If you were trying to decide between these two cameras, you can rest easy knowing the Sony A7III holds its own under the stars against the likes of the D850. The files are clean, the battery lasts a long time, and it was a lot of fun to use in the field. I'm going to personally continue to use my D850 for most of my astro work simply because I have the sigma lens ready for it, but once I build up a better collection of E-Mount glass, I wouldn't hesitate for a second to bring the Sony out solo.
With that said, you absolutely don't need either of these expensive cameras to get started taking pictures of the night sky or subjects in low light. I wrote another blog post way back in 2015 detailing what you need to get started photographing the night sky, and honestly, I should probably update it because even many phones now can take pretty decent images of the night sky with the night/astro modes some of them are equipped with now.
I've also got a landscape and astrophotography workshop coming up in June you may be interested in. We spend a long weekend in the U.P. camping and taking pictures together as I guide a small group through the DeTour State Forest Campground trails and shorelines on Lake Huron for sunrises, sunsets, and nights under the stars. Only a few slots remain open - claim one for yourself today and join us this summer!