Sigma 18-50mm F2.8 DC DN Review

Over the lifetime of Sony’s APS-C lineup, Sigma has put out some really incredible lenses, namely the iconic Sigma trio. Their primes are famous, but their 18-50 zoom is also worth taking a look at.

Per the company’s marketing, the Sigma 18-50mm F2.8 DC DN is supposedly the “world’s lightest and smallest F2.8 zoom lens”. As a lover of small kits, I just HAD to test this thing out myself, so I rented it out for a couple weeks.

Why You Can Trust Me

Chance (that’s me) has been practicing photography for 10 years and has been a paid professional for most of it. I bought my first Sony in 2018 so this website is the culmination of about 5 years of Sony experience (full site history). This was actually the first lens I rented for the website and I had it for about 12 days (read how I review/test gear).

So, in this review, I’ll be covering my hands-on impressions of Sigma’s incredible zoom (spoiler alert), along with sharing dozens of sample photos. Let’s dive in.

  • Sharp/consistent image quality
  • Incredibly compact for a zoom lens
  • Autofocus is reliable and fast
  • Solid long-lasting build quality
  • Not fully sealed (just rubber gasket)
  • Heavy flaring without lens hood
  • No image stabilization

Verdict: Look, I’m just going to say it: this is the best zoom lens for APS-C cameras. Seriously, it combines great image quality, a versatile zoom range, compact build, and great autofocus. I wholeheartedly recommend it.

Milwaukee sunset over lake Michigan
Gorgeous sunset captured at Milwaukee’s lakefront.

Size & Weight

So, let’s first talk about one of the main strong points of this lens: the size & weight! Despite having a versatile range and a fixed F2.8 aperture, Sigma has managed to make this lens QUITE small, coming in at only 2.9 inches (7.3cm).

The barrel does, however, extend a bit when zoomed, but it’s a fairly negligible amount. Honestly, when I took it out of the box and put it next to my Sigma 30mm F1.4, I was blown away that they were almost the same size. How is this even optically possible?

sigma 18-50mm f2.8 on white background

Big props to Sigma for managing to make such a tiny F2.8 zoom. As for its heft, I’m generally less concerned about weight versus size, but this compact zoom weighs a rather conservative 10.2oz (289g). While this isn’t incredibly light, it is, again, quite impressive for a zoom lens with these specs.

I’m just really impressed with how they’ve managed to engineer such a small lens with these specs. Lenses like this are what originally lead me to abandon my bulky DSLR and switch to a mirrorless system. It just fits so well on my a6000.

sigma 18-50mm f2.8 mounted on sony a6000
The lens on my a6000.

Build Quality

Now, small and compact doesn’t mean poor build quality! The Sigma 18-50mm F2.8 is made out of a mix of metal and “thermally stable composite” which is just Sigma’s way of saying high quality plastic.

While I haven’t been able to test the longevity of this lens specifically, the Sigma 30mm F1.4 shares the same materials and has lasted me over four years with no issues. During my tests, I accidentally smacked it into a concrete wall (was running to try to get a shot) and it didn’t sustain any damage, so that’s a good sign for its longevity…

sigma 18-50mm f2.8 lens on table

Included with the lens is a bog-standard petal shaped lens hood. It does its job well enough, protecting the front element from smudges, bumps, and flaring. It’s reversible and, despite also being made of plastic, is pretty durable.

The hoods on my other Sigma lenses have held together quite well over the years so I expect this one to be similar. My only complaint is that my hood felt almost a little loose. It held on just fine, but a light bump would loosen it.

I have a bad habit of gripping my lenses by the hood sometimes, and I almost dropped this one due to how loose it was. I’m not sure if this is intentional, I may have just gotten a slightly worn down copy.

side view of the sigma 18-50mm f2.8
Glamour shot of the lens.

As for weather-sealing, the lens does offer a rubber gasket around the lens mount, but nothing more than that. Either way, this is still nice to see for an APS-C lens, especially at this price point. I took it out during a light rainstorm and didn’t have any issues, but I didn’t want to push it too far as my a6000 itself lacks any sort of weather sealing.

Overall, I’d say the lens definitely feels high quality and built to last. As I mentioned prior, I’ve owned other APS-C Sigma lenses for a while and they’ve been nothing short of amazing in terms of longevity.

glamour photo of the sigma 18-50mm f2.8

As for ergonomics, the lens is a joy to use. As I stated prior, it balances SO well on my a6000. The zoom ring offers perfect resistance that allows for easy turning while being “tight” enough to feel tactile. I observed no zoom creeping, which is an issue some zooms suffer from (where, when the lens is facing down, it slowly “zooms” in or out due to gravity).

The rings are also incredibly grippy (despite being plastic), which is really nice especially in colder weather (big gloves and numb fingers). There are no buttons or switches, so no physical AF/MF switch, but that’s to be expected on a lens that’s this compact, so no complaints from me there.

Overall, the Sigma 18-50mm F2.8 is a joy to use, feeling perfectly perfectly well balanced and comfortable on my a6k. You can really tell this thing was purpose-built for Sony APS-C.

sigma c logo
As always, there is the iconic Sigma “C” logo.

Aesthetically, the lens is a bit boring but not necessarily in a bad way. The lens barrel is very simple, featuring a large zoom ring and a smaller focus ring.

There’s a focal length scale, the typical Sigma “C” logo, and the name of the lens engraved just above the focus ring. Besides that, it’s all sleek polycarbonate/metal. The white text engravings pop really nicely against the sleek black metal, and the whole lens gives off a very nice and minimalist vibe.

long exposure of a city street
Climbed a building for this shot. 18mm and 13s exposure.

Image Quality

Next up, let’s talk about sharpness. I generally don’t get very scientific in my reviews, so don’t expect any sort of MTF charts or other complicated graphs. I usually just pixel peep to the extreme at various F-stops and focal lengths.

When shooting at the widest end of the focal range, we actually see pretty respectable performance. At F2.8, there’s a bit of moderate softness near the corners, but otherwise the whole frame looks pretty nice.

Stopping down, even just a little (to F4, for example), shows noticeable improvement around the corners. More than adequate landscapes or any other sort of wide-angle subjects. Speaking of stopping down, the lens produces some surprisingly nice sun-stars at tight apertures. Honestly, I’m pretty impressed here, as a lot of budget zoom lenses really fall apart when shot at max aperture near the wide end of their zoom range.

skyline of Milwaukee at sunset
Panorama stitch of my city’s beautiful skyline.

On the other end of the zoom range we have 50mm. I shot a LOT at 50mm F2.8 and found that while corners tended to be a little soft, centers were razor sharp. The corner softness wasn’t a big concern to me, as I was generally using this focal length for portraiture or other center-focused subjects (cars, pets, etc.).

Still, stopping down slightly evens out the corners quite a bit, allowing for some really nice telephoto landscape potential (or panorama stitches!). So yeah, the Sigma 18-50mm F2.8 is very, very sharp given that it’s a budget zoom lens.

milwaukee skyline from riverwest
50mm makes for some really nice telephoto landscapes.

Now, we’ll look at optical flaws such as distortion, vignette and that sort of thing. First up, we have distortion… and yes, it’s quite heavy. The tighter end of the zoom range (40-50mm or so) suffered from some minor pincushion distortion, but the wider range wasn’t so lucky.

At 18mm, this thing suffers from pretty substantial barrel distortion. I was able to fix a lot of it in post-processing, but I did notice some architecture shots still had a bit of bendy-ness along straight lines. I wouldn’t let this scare you away, as post-processing can usually fix it (Lightroom has a lens profile), but I’ll include an example below for your consideration.

Next up, we have flaring. I didn’t have any problems with artificial lighting, being able to shoot directly into streetlights and whatnot with only minimal ghosting. Shooting in sunlight, however, was brutal. If the sun is directly in the frame, expect some pretty major flaring.

I’ve posted two examples below. The first shot was in direct sunlight, but for the second image I angled the lens down and used my hand as a makeshift “lens hood extension”. You can see the massive difference in flaring.

Moving onto vignette next. I don’t tend to worry about vignette, but I did observe pretty poor performance. The tighter end of the zoom range, once again, struggles very little, but at the wide end there is noticeable darkening around the corners. Stopping down remedies it.

I’d say it’s roughly a -1.5EV difference at 18mm F2.8, so it’s largely fixable in post-processing. You do run the risk of introducing digital noise though (when pushing exposure up in post) in dark conditions.

Finally, let’s look at chromatic aberrations. I found VERY little issue here, even in some of my more extreme tests. Generally, I find that shooting branches against a sunlit sky is a great test of CA performance and this lens didn’t struggle in that regard.

swan boats on a lake with skyline
A pleasant evening in Milwaukee (don’t look to closely at all the noise).

Next up, bokeh! The lens is no bokeh beast (F2.8 aperture), but it actually puts out some pretty decent results near the tighter end of the zoom range. The bokeh is creamy and pleasant. It’s not quite on the same level as a dedicated portrait lens such as the Sigma 56mm F1.4, but I was really happy with the results I was able to get.

In “busy” photographs (with cluttered backgrounds) or at the wider end of the zoom range, the bokeh can look a bit rough and chaotic. At 50mm, simple backgrounds produce clean bokeh balls. I understand bokeh is a bit of a subjective thing, so I’ve included a some samples below. There’s F2.8, 5.6, and F8 at both 18mm and 50mm.

Bokeh samples at various F-stops (swipe for more).

Sigma 18-50mm F2.8 Portrait Samples

As I said before, the Sigma 18-50mm F2.8 won’t match a dedicated portrait lens, but it performs great for photographing people. I found that shooting 50mm F2.8 offered great subject isolation, and the natural vignette went a long way in really isolated my subjects in the frame. Once again, pictures are worth a thousand words, so check out a few of my portrait samples below.

Macro & Minimum Focus

For those considering dabbling in macro, I want to mention the INCREDIBLY short focus distance on this lens. At 18mm, the minimum focusing distance is literally just an inch (2.5cm).

At this focal length, that means you have to stick the lens almost directly up to the subject, casting shadows and creating some insane field curvature. For macro enthusiasts though, zooming in (and backing up) offers better results. Focusing distance at 50mm is roughly 12 inches (30cm).

sunset over the Milwaukee river
A sunset cruise down the river.

This lens obviously can’t compete with a real macro lens, but it offers decent results. At 18mm, you’ll get a magnification ratio of roughly 1:2.8. Zooming into 50mm is closer to a 1:5 ratio. So, if you’re looking to just dabble in macro subjects, this lens is certainly capable! I’ve included a couple examples below.

Autofocus

Alrighty, so everything else looks good, but how is the autofocus on the Sigma 18-50mm F2.8? Really solid, actually. Originally I assumed it would use the same focusing system as the Sigma trio, but after using it for a while, it seems to be even faster and more reliable than my 30mm F1.4.

Performance was nearly flawless even in low light. I rarely had shots with missed focus, and those were generally in REALLY tough high-contrast situations. EyeAF worked fairly well, and the lens tracked VERY effectively with AF-C (continuous AF).

The stepping-motor is also quite quiet. When doing a quick video test, I found that the autofocus was barely perceptible on the (crappy) onboard microphone of my a6000. I’d imagine that using an actual dedicated microphone would be even better.

Video performance was quite fast and reliable as well, and I also noticed absolutely zero focus breathing. For those with stabilized bodies, this lens could be golden for video use.

people sitting on grass overlooking city
A small neighborhood music festival in Milwaukee.

Manual Focus

So, now that we’ve covered autofocus, let’s cover the art of manually focusing with your own hands. The manual focus experience is pretty typical of a modern autofocus lens.

The focus ring is well dampened and feels precise enough, but the awkward positioning (near the lens mount) made it a bit hard to grip. On the rare occasion I switched to MF, I found that it was precise enough but, again, the positioning of the focusing ring was just weird to me.

Finally, let’s talk about stabilization. As I alluded to earlier, the Sigma 18-50mm F2.8, unfortunately, does not offer image stabilization. While this is certainly a downside, I’m not surprised. Including stabilization would have added a bit of bulk (and cost) to this compact lens, plus newer Sony a6000 series cameras offer IBIS anyway. Still, as someone who still uses an a6000, the lack of stabilization is still kind of a bummer.

skyscrapers against a sunset sky
Loved the lighting in this shot. The skyscrapers lit up with the sunset.

Final Thoughts

I personally think the Sigma 18-50mm F2.8 is incredible, but I’d like to offer some alternatives before we round out the article. First up, if you’re upgrading from the kit lens, you’ll find that the Sigma will blow it away in literally every single aspect.

The main competitor would be the Sony 16-55mm F2.8. It’s a beast of a lens and offers similar image and build quality. You also gain a little bit of range on both the wide and telephoto ends. The two caveats, however, are that it’s much larger AND much more expensive than the Sigma.

The second competitor would be the Tamron 17-70mm F2.8. The Tamron offers a much larger focal range (and similar sharpness), but is HUGE and more expensive. It does, however, offer stabilization.

people having a picnic downtown
Picnic with a view.

Frankly, I find the Sigma 18-50mm F2.8 hard to beat. Sigma has put out nothing but quality lenses over the last few years, and this one is no exception.

A versatile zoom range, great image quality, and a solid yet compact build all come together to make this one of my favorite lenses I’ve ever used. Generally I’m a prime purist, but this Sigma has opened my eyes. Like I said earlier, lenses like this are what convinced me to originally switch to mirrorless from a bulky DSLR setup.

boat sailing towards Hoan Bridge
Boating in the Bay.

So, if I’ve convinced you to pick it up for yourself (and why wouldn’t you? it’s fantastic), I’ll leave a link below to purchase. Thanks for reading!

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Sigma 18-50mm F2.8 Sample Photos

sunset over Milwaukee's skyline
Yet another sunset picture.
abandoned shopping mall
An abandoned shopping mall in my city, left to rot over 20 years.
street scene at the Bristol ren faire
“Street scene” at the Ren Faire.

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