Sigma 18-50mm F2.8 DC DN Contemporary Lens Review

Nearly everyone needs a general-purpose zoom lens, and the Sigma 18-50mm F2.8 DC DN Contemporary Lens is an outstanding choice for APS-C camera owners (and not a bad choice for full-frame camera owners willing to work within the smaller image circle).

The advantages of a smaller image circle are reduced cost, decreased size, and a lower price, and the Sigma 18-50mm F2.8 DC DN Contemporary Lens embodies those attributes while still providing a zoom range, wide aperture, and impressive image quality. This is an attractively designed lens with an especially-valued focal length range.

If those attributes do not attract your attention, that this is the review-time best-selling APS-C zoom lens should.

Note that this is the first Sigma lens available with a Canon RF mount.

Focal Length Range

Back to Top

The focal length range is the first aspect to consider for zoom lens selection. Focal length drives subject distance choices, which determine perspective.

Most subjects can be photographed with any focal length, but not all angles of view provided by those focal lengths are practical from a working distance perspective, and they do not all provide the ideal relational perspective when the desired subject framing is obtained. For example, photographing a group of 15 people with a 600mm lens requires a working distance that might require a large sports field to keep all group members in the frame, and a phone may be required to communicate with them.

The moderately wide-angle through short telephoto 18-50 (27-75mm full-frame angle of view equivalent) focal length range covers a huge range of general-purpose needs, making it an ideal option for photographing a vast range of subjects. This is the type of lens you can take when you are unsure which focal lengths you will need, and it will usually be found to be the right choice.

The 18-50mm range is great for photographing people, and it is ideal for portraits, weddings, parties, events, documentaries, interviews, lifestyle, theater, fashion, studio portraiture, candids, and even some sports. Use 50mm for head and shoulders portraits and the wider end for groups and environmental imagery.

This lens is a perfect choice for media and photojournalistic needs, and it is a great option for street photography.

This lens is a good choice for landscape and cityscape photography, with compositions being ideally captured using every focal length available in this lens. It is not difficult to create compelling landscape compositions using the 18mm perspective while still providing emphasis on a foreground subject against an in-focus background while providing the viewer a sense of presence in the scene. 50mm works great for mildly-compressed landscapes featuring distant subjects such as mountains.

With a wide aperture, this lens is attractive for photographing the night sky, with the 18mm end typically being of most interest in that regard.

This lens is well-suited for commercial photography, and the wide end of the range is ready to capture exterior architecture and larger interior spaces. Cityscapes, countrysides, flowers, medium and large products, and much more are in this lens's capabilities list.

Here is a focal length comparison:

Load Comparison Images

These images illustrate the heart of the APS-C general-purpose focal length range.

Max Aperture

Back to Top

As of review time, few zoom lenses have a maximum aperture opening wider than this one, and the wide aperture is a big advantage.

Wide apertures are helpful for stopping action, both that of the subject and the camera, in low-light levels while keeping ISO settings low. In addition, wide apertures benefit AF systems, enabling them to work better in low-light environments.

While having an f/2.8 aperture may not be greatly advantageous from ISO and shutter speed perspectives when photographing under bright light (daylight, for example), wide apertures are useful for creating a strong background blur that makes a subject cleanly stand out, isolated from an even highly distracting background, at any time of the day.

These examples illustrate the maximum blur this lens can create:

Load Comparison Images

A disadvantage of a wide aperture is the required increased physical size of the lens elements. Larger lens elements come with heavier weight and higher costs. This lens avoids those disadvantages.

Most will appreciate this lens's constant max aperture, enabling f/2.8 throughout the focal length range.

Image Stabilization

Back to Top

The Sigma 18-50mm F2.8 DC DN Contemporary Lens does not feature image stabilization. Omitting the optical stabilization system reduces the size, weight, complexity, and cost. However, image stabilization is a useful feature.

Sony addresses that omission with Steady Shot IBIS (In-Body Image Stabilization) in their Alpha cameras. In addition to reducing camera shake, the stabilized imaging sensor provides a still viewfinder image, enabling careful composition. Furthermore, sensor-based AF takes advantage of the stabilized view for improved accuracy.

With no IS switch on the lens, the camera menu must be used to enable or disable IBIS or check the current settings. This extra step is a slight impediment to working quickly, going from tripod mounted to handholding, for example.

Image Quality

Back to Top

One aspect we never want to be compromised is the image quality produced by a lens, especially a most frequently used lens. How sharp is Sigma 18-50mm F2.8 DC DN Contemporary Lens? That is the first question most of us want to be answered, and I think you will like this answer.

At the wide end, this lens is impressively sharp at f/2.8 with little improvement showing or needed at f/4. The wide-open results slowly transition to slightly softer at 50mm f/2.8, where a modest improvement at f/4 brings on excellent sharpness.

Moving farther out on the image circle, where light rays are refracted to a stronger angle than in the center, lenses typically show decreased sharpness. However, this lens shows relatively little image quality degradation. Corner image sharpness is not far behind the center of the frame results.

Taking the testing outdoors, we next look at a series of center-of-the-frame 100% resolution crop examples. These images were captured in RAW format using a Sony Alpha 1 and processed in Capture One using the Natural Clarity method. The sharpening amount was set to only "30" on a 0-1000 scale. Note that images from most cameras require some level of sharpening, but too-high sharpness settings are destructive to image details and hide the deficiencies of a lens.

Load Comparison Images

Again, these results are good.

Next, we'll look at a series of comparisons showing 100% resolution extreme top left corner crops captured and processed identically to the above center-of-the-frame images. The lens was manually focused in the corner of the frame to capture these images. The first pair of results in each set is from the bottom left of the frame, and the balance are from the top left.

Load Comparison Images

Samples taken from the outer extreme of the image circle, full-frame corners, can be counted on to show a lens's weakest performance. Results this nice are especially impressive from a zoom lens.

This lens does not exhibit focus shift, the plane of sharp focus moving forward or backward as the aperture is narrowed (residual spherical aberration or RSA).

When used on a camera that utilizes a lens's entire image circle, a lens can be expected to create peripheral shading at the widest aperture settings. The about 3 stops of shading at 18mm f/2.8 is noticeable. The wide-open shading quickly drops off to well under 2 stops at 24mm and then increases to about 2.5 stops at 50mm. At f/4, vignetting decreases by approximately 1 stop, with little reduction seen after f/5.6, where about a stop of shading remains deep in the corners.

One-stop of shading is often used as the visibility number, though subject details provide a widely varying amount of vignetting discernibility. Vignetting is correctable during post-processing with increased noise in the brightened areas being the penalty, or it can be embraced, using the effect to draw the viewer's eye to the center of the frame. Study the pattern shown in our vignetting test tool to determine how your images will be affected.

Lateral (or transverse) CA (Chromatic Aberration) refers to the unequal magnification of all colors in the spectrum. Lateral CA shows as color fringing along lines of strong contrast running tangential (meridional, right angles to radii) with the mid and especially the periphery of the image circle showing the most significant amount as this is where the most significant difference in the magnification of wavelengths typically exists.

With the right lens profile and software, lateral CA is often easily correctable (often in the camera) by radially shifting the colors to coincide. However, it is always better to avoid this aberration in the first place.

Color misalignment can be seen in the site's image quality tool, but let's also look at a set of worst-case examples. The images below are 100% crops from the extreme top left corner of Sony a1 frames showing diagonal black and white lines.

Load Comparison Images

Only black and white colors should appear in these images, with the additional colors indicating a minor presence of lateral CA. Common is for a zoom lens to have noticeable color separation in the corners at the focal length extremes (with a reversing of the fringing colors) and little lateral CA at mid-range focal lengths.

A relatively common lens aberration is axial (longitudinal, bokeh) CA, which causes non-coinciding focal planes of the various wavelengths of light. More simply, different colors of light are focused to different depths. Spherical aberration along with spherochromatism, or a change in the amount of spherical aberration with respect to color (looks quite similar to axial chromatic aberration but is hazier) are other common lens aberrations to observe. Axial CA remains somewhat persistent when stopping down, with the color misalignment effect increasing with defocusing. The spherical aberration color halo shows little size change as the lens is defocused, and stopping down one to two stops generally removes this aberration.

In the real world, lens defects do not exist in isolation, with spherical aberration and spherochromatism generally found, at least to some degree, along with axial CA. These combine to create a less sharp, hazy-appearing image quality at the widest apertures.

The examples below look at the defocused specular highlights' fringing colors in the foreground vs. the background. The lens has introduced any fringing color differences from the neutrally-colored subjects.

Load Comparison Images

The color separation illustrated here ranges from minor at 18mm to strong at 50mm.

Bright light reflecting off lens elements' surfaces may cause flare and ghosting, resulting in reduced contrast and sometimes interesting, usually destructive visual artifacts. The shape, intensity, and position of the flare effects in an image are variable, dependent on the position and nature of the light source (or sources), selected aperture, shape of the aperture blades, and quantity and quality of the lens elements and their coatings. Additionally, flare and ghosting can impact AF performance.

On this lens, Sigma utilizes Super Multi-Layer Coating to combat flare. Additionally, relatively low (especially for a zoom lens) 13-element count is helpful in this regard. This lens produced minor flare effects at most, even at narrow apertures in our standard sun in the corner of the frame flare test. This is excellent performance.

Flare effects can be embraced or avoided, or removal can be attempted. Removal is sometimes challenging. Thus, high flare resistance is a welcomed trait of this lens.

Two lens aberrations are particularly evident in images of stars, mainly because bright points of light against a dark background make them easier to see. Coma occurs when light rays from a point of light spread out from that point instead of being refocused as a point on the sensor. Coma is absent in the center of the frame, gets worse toward the edges/corners, and generally appears as a comet-like or triangular tail of light which can be oriented either away from the center of the frame (external coma) or toward the center of the frame (internal coma). Coma clears as the aperture is narrowed. Astigmatism is seen as points of light spreading into a line, either sagittal (radiating from the center of the image) or meridional (tangential, perpendicular to sagittal). This aberration can produce stars appearing to have wings. Remember that Lateral CA is another aberration apparent in the corners.

The images below are 100% crops taken from the top-left corner of Sony Alpha 1 images captured at the widest available aperture.

Load Comparison Images

The peripheral stars are not rendered as perfect dots in these examples, but these results are normal (or slightly better).

The phrase "... the use of in-camera aberration correction further eliminates optical imperfections such as distortion ..." [Sigma] warns of impending geometric distortion.

This is a standard zoom lens, and the usual standard zoom lens geometric distortion description holds true, with the amounts being strong in this case. This lens has significant barrel distortion at the wide end, transitions into negligible distortion at approximately 24mm, and has moderately strong pincushion distortion by 35mm and through 50mm.

With increasing frequency, manufacturers are relying on software over physical lens design to handle geometric distortion. Most modern lenses have correction profiles available (including in-camera), and distortion can easily be removed using these. Still, geometric distortion correction requires stretching which is detrimental to image quality.

As seen earlier in the review, it is easy to illustrate the strongest blur a lens can create. Due to the infinite number of variables present among all available scenes, assessing the bokeh quality is considerably more challenging. Here are some f/11 and f/8 (for diaphragm blade interaction) examples.

Load Comparison Images

The first example set shows f/11 defocused highlights being relatively smoothly filled, but with the 7 aperture blades turning the circle into a polygon (a heptagon, to be specific).

The second set of examples shows full f/8 images reduced in size and looking normal.

Except for a small number of specialty lenses, the wide aperture bokeh in the frame's corner does not produce round defocused highlights, with these effects taking on a cat's eye shape due to a form of mechanical vignetting. If you look through a tube at an angle, similar to the light reaching the frame's corner, the shape is not round. That is the shape we're looking at here.

Load Comparison Images

As the aperture narrows, the entrance pupil size is reduced, and the mechanical vignetting absolves with the shapes becoming rounder.

A 7-blade count diaphragm will create 14-point sunstars (diffraction spikes) from point light sources captured with a narrow aperture. In general, the more a lens diaphragm is stopped down, the larger and better-shaped the sunstars tend to be. The examples below were captured at f/16.

Load Comparison Images

While the star effects are significant, the rays are multi-pointed.

The design of this lens is illustrated below.

Overall, the Sigma 18-50mm F2.8 DC DN Contemporary Lens produces sharp image quality, but there is strong geometric distortion over much of the zoom range and noticeable color separation at the longer end of the range.

Focusing

Back to Top

Driven by a stepping motor, the Sigma 18-50mm F2.8 DC DN Contemporary Lens smoothly autofocuses with fast speed. The focusing is internal and practically silent.

Remember that (at least some) cameras, including the Sony Alpha 1, defocus the image slightly before final focusing in AF-S mode, even if the subject was initially in focus, adding to the focus lock time. Autofocus lock speed is noticeably faster in AF-C mode.

With adequate contrast on the subject, this lens focuses in dark environments — especially dark for what is expected from an f/2.8 lens. As usual, autofocusing becomes slow in the lowest functioning light levels.

If the image is out of focus, it most likely is immediately deleted. The number one requirement of an AF system is to focus accurately, and this lens performed superbly in this regard. Nearly all images were ideally focused.

As illustrated in the 100% crops below, the reviewed lens does not exhibit parfocal-like characteristics. When focused at 50mm, zooming to wider focal lengths results in focus blur.

Load Comparison Images

If you adjust the focal length, re-establish focus. This rule applies to most zoom lenses.

Normal is for the scene to change size in the frame (sometimes significantly) as the focus is pulled from one extent to the other. This is focus breathing, a change in focal length resulting from a change in focus distance. Focus breathing impacts photographers intending to use focus stacking techniques, videographers pulling focus (without movement to camouflage the effect), and anyone critically framing while adjusting focus.

At 18mm, this lens produces a small change in subject size through a full extent focus distance adjustment. The focus magnification change becomes modest at 50mm.

Load Comparison Images

This lens does not have an AF/MF switch. Changing this frequently used camera setting requires using the menu system (or a camera switch on some models).

This lens has a small, plastic-ribbed focus ring that has the same diameter as the lens barrel — is it not especially easy to find. The ring rotates smoothly with ideal resistance.

The manual focus adjustment rate is variable, based on the ring's rotation speed. At 18mm, a full extent focus distance change requires 690° when turning the focus ring slowly. At 50mm, the required rotation increases to 990°. Turn the ring fast, and 450° of rotation does the same for both tested focal lengths.

The slow rotation manual focus adjustment steps are just short enough for high-precision focusing.

With a minimum focus distance of 4.8" (121mm), this lens has a huge 0.36x maximum magnification spec.

The chart below includes a set of complementary Sigma lenses along with more-similar alternatives.

Model	Min Focus Distance "(mm)		Max Magnification
Canon EF-M 15-45mm f/3.5-6.3 IS STM Lens	9.8	(250)	0.25x
Canon EF-M 18-55mm f/3.5-5.6 IS STM Lens	9.8	(250)	0.25x
Sigma 16mm F1.4 DC DN Contemporary Lens	9.8	(250)	0.10x
Sigma 30mm F1.4 DC DN Contemporary Lens	11.8	(300)	0.14x
Sigma 56mm F1.4 DC DN Contemporary Lens	19.7	(500)	0.14x
Sigma 18-50mm F2.8 DC DN Contemporary Lens	4.8	(121)	0.36x

At 18mm, a subject measuring approximately 2.2" x 1.5" (56 x 37mm) fills a full-frame imaging sensor at this lens's minimum focus distance. At 50mm, a 3.3 x 2.2" (84 x 56mm) subject does the same.

Load Comparison Images

The USPS love stamps shared above have an image area that measures 1.05 x 0.77" (26.67 x 19.558mm), and the overall individual stamp size is 1.19 x 0.91" (30.226 x 23.114mm).

Somewhat unusual is that this lens is capable of a significantly higher reproduction ratio at 18mm than 50mm. However, the 18mm peripheral image quality goes soft, even at f/16 (also notice the strong barrel distortion). While the resulting look has artistic qualities, it does not suit all requirements.

The 50mm minimum focus distance example shows far better image sharpness across the frame, with the strong barrel distortion swapped for moderate pincushion distortion.

Need a shorter minimum focus distance and higher magnification? Mount an extension tube behind this lens to significantly decrease and increase those respective numbers. Extension tubes are hollow lens barrels that shift a lens farther from the camera, allowing shorter focusing distances at the expense of long-distance focusing. Electronic connections in extension tubes permit the lens and camera to communicate and otherwise function normally. As of review time, Canon and Sony do not publish extension tube specs or manufacture these items in compatible mounts, but third-party extension tubes are available.

This lens is not compatible with extenders/teleconverters.

Build Quality & Features

Back to Top

The Sigma 18-50mm F2.8 DC DN Contemporary Lens has an aesthetically pleasing design that maintains tight tolerances and has a quality finish. The straight design aids in comfortable use.

Load Comparison Images

"To keep the lens as light as possible, SIGMA constructed the body from carefully selected materials. A polycarbonate called Thermally Stable Composite (TSC) was used for the construction of the barrel, which is sleek, robust, and importantly has a thermal conductivity close to that of aluminum. This ensures stable performance and good operability when used in changing temperatures. By deliberately using metal for some of the internal structure, the parts could be much thinner and have a higher rigidity, ensuring the lens can stand up to frequent, heavy use." [Sigma]

As is normal for standard zoom lenses, the 18-50 DC DN extends when zoomed to its longest focal length, but the full extension is only 0.86" (21.9mm).

Most photographers using this lens will frequently adjust the focal length, and this lens's smooth functioning, sharp-rubber-ribbed, slightly raised zoom ring is easy to find and a pleasure to use. I generally prefer a zoom ring positioned behind the focus ring, but in this case, the forward zoom ring position provides a natural grip location for the lens, and the small focus ring is tucked in close to the mount where it stays out of the way.

180° of the area between the rings features molded-in ribs that facilitate grip for mounting and dismounting the lens.

This lens has no buttons or switches. As hinted earlier, the AF/MF button is one I miss the most. Positive is that the lack of switches means increased reliability and decreased opportunity for dirt and moisture penetration.

"Are Contemporary lenses weather sealed? Contemporary lenses feature a gasket at the mount that protects against dust and moisture, but none feature sealing throughout the lens body (this is an additional reason that Contemporary lenses are more affordable). That said, the vast majority of contaminants work their way into lenses through the rear mount, so as long as they aren’t abused, these lenses will provide many years of trouble-free use, even in moderate weather. For regular use in more extreme conditions, Art or Sports lenses are the way to go." [Sigma]

The Canon RF mount version is shown below.

This Sigma lens is compatible with advanced mirrorless camera features, including Eye AF, in-camera lens correction (shading, chromatic aberration, distortion), and camera-based lens firmware updates.

Among normal zoom lenses in general, this one, promising only an APS-C-sized image circle, is tiny and light.

Model	Weight oz(g)		Dimensions w/o Hood "(mm)		Filter	Year
Canon EF-M 15-45mm f/3.5-6.3 IS STM Lens	4.6	(130)	2.4 x 1.8	(60.9 x 44.5)	49	2015
Canon EF-M 18-55mm f/3.5-5.6 IS STM Lens	7.4	(210)	2.4 x 2.4	(60.9 x 61)	52	2012
Sigma 16mm F1.4 DC DN Contemporary Lens	14.3	(405)	2.8 x 3.6	(72.2 x 92.3)	67	2021
Sigma 30mm F1.4 DC DN Contemporary Lens	9.4	(265)	2.6 x 2.9	(64.8 x 73.3)	52	2016
Sigma 56mm F1.4 DC DN Contemporary Lens	9.9	(280)	2.6 x 2.3	(66.5 x 59.5)	55	2018
Sigma 18-50mm F2.8 DC DN Contemporary Lens	10.2	(290)	2.5 x 2.9	(64.5 x 74.5)	55	2017

For many more comparisons, review the complete Sigma 18-50mm F2.8 DC DN Contemporary Lens Specifications using the site's lens specifications tool.

Here is a visual comparison of the small Sigma DC DN lenses being simultaneously evaluated:

Positioned above from left to right are the following lenses:

Sigma 16mm F1.4 DC DN Contemporary Lens
Sigma 30mm F1.4 DC DN Contemporary Lens
Sigma 56mm F1.4 DC DN Contemporary Lens
Sigma 18-50mm F2.8 DC DN Contemporary Lens

The same lenses are shown below with their hoods in place.

Use the site's product image comparison tool to visually compare the Sigma 18-50mm F2.8 DC DN Contemporary Lens to other lenses.

This lens features 55mm filter threads. While 55mm enjoys only limited popularity as a filter size, 55mm filters are small and relatively inexpensive.

Sigma always includes the hood, and the LH582-02 Lens Hood ships with the 18-50mm F2.8 DC DN Contemporary Lens. The LH582-02's petal shape is optimized to block as much light outside the utilized image circle as possible. As zoom lens hoods must be tuned for the wide end of the zoom range, less than optimal protection is afforded at the long end. Still, this hood offers reasonable front element protection from dust, water, fingers, limbs, etc., and from flare-inducing bright light.

The hood's interior is mold-ribbed for reduced internal reflections, and the LH582-02's semi-rigid plastic build absorbs some impact, adding a layer of physical protection to the camera and lens. The petal shape looks cool, and another advantage of this hood shape is easier installation alignment (simply align the small petal to the top), though a round-shaped hood enables the lens to stand on its hood (if conditions permit). The rear portion of the hood is rubberized to, along with the mold-ribbed ring, facilitate installation and removal.

No lens case is included in the box. Consider a Lowepro Lens Case or Think Tank Photo Lens Case Duo for a quality, affordable single-lens storage, transport, and carry solution.

Price, Value, Compatibility

Back to Top

It is not difficult to forecast a Sigma Global Vision lens being a great value, and the Sigma 18-50mm F2.8 DC DN Contemporary Lens is that. This lens has a lot to offer for a low price.

The "DG" refers to full-frame camera compatibility, and the "DN" indicates that this lens was designed for short flange mirrorless cameras. The Sigma 18-50mm F2.8 DC DN Contemporary Lens is compatible with all Canon RF and Sony E mount cameras, including APS-C sensor format models, and it is also available in the Leica L mount. Changing camera brands? Sigma offers a Mount Conversion Service to protect your investment.

Made in Japan, each Contemporary lens is tested with Sigma's proprietary MTF measuring system, ensuring a quality product. In regards to the Sony E-mount version of this lens, Sigma develops, manufactures, and sells lenses based on the specifications of E-mount, disclosed by Sony Corporation under license agreement. The RF lenses are produced under a license agreement with Canon. Sigma provides a 1-year limited warranty, and Sigma USA provides a limited 3-year warranty extension.

The reviewed Sigma 18-50mm F2.8 DC DN Contemporary Lens was online-retail sourced.

Summary

Back to Top

It is no accident that the Sigma 18-50mm F2.8 DC DN Contemporary Lens provides the most used general-purpose zoom range. That feature means it will be an always-mount favorite. The sharp image quality this lens delivers throughout the zoom range backs up that decision.