Sigma 40mm f/1.4 DG HSM Art Lens Review

Want to be impressed? Looking at the image quality delivered by this lens should take care of that desire. It will also create a new one. You are going to want this lens.

Optically, this is one of the best-performing f/1.4 lenses ever.

Announced at the same time, sharing many similarities and being simultaneously reviewed with this lens is the Sigma 28mm f/1.4 DG HSM Art Lens. While some of the Sigma Global Vision Art series lenses have been highly anticipated (as in expected), the 40mm f/1.4 was not. Sigma already had 35mm f/1.4 and 50mm f/1.4 lenses in their Art-series lineup and I have to admit to not seeing this lens coming. Obviously, someone determined that a gap needed to be filled and now there are 12 wide aperture prime Sigma Art lenses (all except two being f/1.4 models) and 19 Art lenses in total for an impressive overall lineup.

As with the rest of the Sigma Art lenses, the aesthetics and build quality of the 40mm f/1.4 Art lens will impress. The focal length is a useful one, featuring great general purpose utility. The size and weight are big and heavy for this lens's class, but not that big overall and still comfortable to use. The price? Not cheap, but from a relative standpoint, not high either. Autofocus performance? Read on.

Focal Length

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"The 40mm F1.4 DG HSM Art is Sigma’s first lens developed originally to live up to the sought-after angle of view and performance standard for a benchmark cine lens." [Sigma]

With a prime lens, you get one focal length and lens selection should begin with choosing the focal length that best suits the subject. When I show you the image quality this lens delivers, you are going to attempt to make this focal length work for even fringe purposes, but let's find center first. Fortunately, center is broad and this focal length has great general purpose utility.

Far more common than 40mm prime lenses are the 35mm and 50mm variants. The angle of view difference between 35mm, 40mm, and 50mm is illustrated below.

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Obviously, 40mm frames a bit tighter than 35mm and a greater bit wider than 50mm. Being in the middle mostly merges the uses of the other two.

Use the 40mm focal length for capturing a natural perspective. This angle of view encourages capture of the big scene but it is not so wide that people and other subjects are readily distorted by the close perspective invited by ultra-wide angles.

Photojournalism is a great use of the 40mm focal length. Portrait and wedding photographers will love the 40mm focal length for full to mid-body portraits and even for group portraits with a small group size, tight-enough spacing or large-enough space to work in. Landscape photographers can make use of all focal lengths, but the 40mm option is a common requirement for this pursuit.

Sports photographers able to get close to their subjects (such as basketball shot from over or under the net) or wanting to capture a wider/environmental view of their events will appreciate this focal length. Parents will love 40mm for capturing their indoor events. As indicated in this section's opening sentence, 40mm is also popular with videographers, especially for creating documentaries.

Want to pick a lens to walk around looking for images to be made with it? This 40mm lens makes a good choice.

Many products look great when captured at 40mm. The 40mm focal length paired with a wide aperture is especially appealing for creative photography.

As usual, I've only scratched the surface of the list of uses here.

APS-C sensor format cameras utilize a smaller portion of the image circle and that means a scene is framed more tightly, with 1.6x or 1.5x being the angle of view multiplier for Canon, Nikon and Sony's lineup. A 40mm lens behind one of these cameras results in a 60mm or 64mm full frame angle of view equivalent. The uses for these angles of view do not vary greatly from the native 40mm full frame angle of view, but more working space is required for the same subject framing. The narrower angle of view encourages a better portrait perspective by increasing the subject distance and enables tighter portrait framing while retaining a pleasing perspective. The narrower angle of view will likely find less application in landscape photography.

Max Aperture

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When you buy a prime lens instead of a zoom, you expect at least one strong advantage to offset the loss of zoom range versatility. Common advantages include smaller size, lighter weight, lower price, better image quality, and/or a wider aperture. This prime lens does not check the first three boxes, but it has big, bold Xs in the last two. I'll cover image quality in the next section, but with only a few exceptions, the f/1.4 max aperture made available by this lens is as wide as DSLR and MILC (Mirrorless Interchangeable Lens Camera) lenses get and no autofocus lens wider than 50mm exceeds the 40 Art's maximum aperture.

The wider the aperture, the more light is able to reach the imaging sensor. Allowing more light to reach the sensor permits freezing action, handholding the camera in lower light levels and/or use of a lower (less noisy) ISO setting. It seems that there is always enough light for this lens to capture a sharp image.

Increasing the aperture size also permits a stronger, better subject-isolating background blur (at equivalent focal lengths). The shallow f/1.4 depth of field must of course be acceptable to you in these circumstances, but shallow depth of field is a highly-desired lens capability, excellent for making the subject pop from a blurred background. Longer focal length lenses are better at creating a strong background blur, but this one can definitely get the job done if the subject is close enough as illustrated in the maximum blur example below.

Those looking for a prime lens often already have a general purpose zoom lens in their kits and 40mm is typically covered by that lens. Compare the background blur of your lens at its maximum-available 40mm aperture.

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Especially if your lens's max aperture is f/4 or f/5.6 at 40mm, the difference between it and f/1.4 is significant.

F/1.4 enables the higher precision AF capabilities (most often the center AF point) in all cameras supporting this feature and f/1.4 presents a bright viewfinder image. This wide aperture is especially valuable after the sun sets, under shade and when shooting indoors, including indoors using only ambient window light.

Note that, especially under full sun conditions, even a 1/8000 shutter speed will often be not fast enough to avoid blown highlights in f/1.4 images (use a neutral density filter to avoid this issue).

Image Quality

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This lens checks the better image quality checkbox. A useful focal length and wide aperture are great to have, but if the lens does not produce high-enough quality images at that aperture, that wide aperture is of less value. While few of us buy lenses to shoot test charts with, these charts are quite revealing of the performance a lens is capable of achieving. The black and white chart details quickly reveal any flaws present.

Test chart captures from the 40 f/1.4 Art lens are quite impressive and have generated a collective "Wow!". In the center through full frame periphery of the image circle, this lens performs impressively at f/1.4, competing strongly for the title of best f/1.4 lens performance ever. Especially with contrast improving, results become noticeably sharper only 1/3 stop down at f/1.6. This lens's f/2 results are extremely impressive and the f/2.8 results are slightly even more so. This lens is ready for the highest-resolution cameras available.

In addition to our standard lab tests, I like to share some real-world examples. The images below are 100% resolution crops from images captured in RAW format using a Canon EOS 5Ds R. The images were processed in Canon's Digital Photo Professional using the Standard Picture Style with sharpness set to "1" (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). These examples are from the center of the frame.

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The f/1.4 results show great resolution and, with a small amount of contrast and sharpening added, they would look especially nice. While this lens performs strongly at f/1.4, the amazingness of the f/2 image quality is attention-getting. The contrast pop that happens at f/2 is noticeable and these results are jaw-dropping. You can stop down to f/2.8 if you wish, but the f/2 image quality is hard to improve upon at 50 MPs.

Focus shift, the plane of sharp focus moving forward or backward as the aperture is narrowed (residual spherical aberration), is only a minor issue with this lens. At f/2 and f/2.8, much of the depth of field increase is beyond the focused-on subject, but the foreground comes into stronger focus at f/4 and narrower apertures.

Here is a look at the extreme top-left corner image quality. These images were processed identically to the center results with the subject being manually focused in the corner.

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If you look carefully into the branches until the sharpest are found, you will see this lens turning in impressively-sharp corner image quality even at f/1.4. Stopping down increases depth of field and reduces peripheral shading which improves contrast.

When used on a camera that utilizes a lens's entire image circle, peripheral shading can be expected at the widest aperture settings. Ultra-wide aperture lenses tend to show strong peripheral shading wide open and the about-3-stops of shading in the 40 f/1.4 Art's corners is indeed relatively strong, but about as expected. Stopping down one stop reduces the shading by about 50% to roughly 1.4-stops. At f/2.8, the shading drops well under the often-visible 1-stop mark to about 0.6-stops. Shading stops clearing at f/4 with about 0.5-stops remaining in the corners throughout the balance of the aperture range.

Vignetting can be corrected during post-processing with increased noise in the brightened areas being the penalty. Vignetting can also be embraced, using the effect to draw the viewer's eye to the center of the frame.

The effect of different colors of the spectrum being magnified differently is referred to as lateral (or transverse) CA (Chromatic Aberration). 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 greatest amount as this is where the greatest difference in the magnification of wavelengths exists.

While lateral CA is usually easily corrected with software (often in the camera) by radially shifting the colors to coincide, it is of course better to not have it in the first place. Any color misalignment present can easily be seen in the site's image quality tool, but let's also look at a worst-case example, a 100% crop from the extreme top left corner of an ultra-high resolution 5Ds R frame.

There should be only black and white colors in these images and the lack of additional colors indicates that this lens is performing impressively in this regard.

A relatively common lens aberration is axial (longitudinal, bokeh) CA, which causes non-coinciding focal planes of the various wavelengths of light, or 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 look for. Axial CA remains at least somewhat persistent when stopping down with the color misalignment effect increasing with defocusing while 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.

In the example above, look at the fringing colors in out of focus areas of the image. In such an example, an ultra-wide aperture lens usually produces specular highlights in the foreground showing purple fringing and specular highlights in the background showing green fringing, indicating the presence of these defects. Such defects are impressively absent in the results from this lens.

Flare is caused by bright light reflecting off of the surfaces of lens elements, resulting in reduced contrast and interesting artifacts. The shape, intensity, and position of the flare in an image is variable and depends on the position and nature of the light source (or sources) as well as on the selected aperture, shape of the aperture blades and quality of the lens elements and their coatings. I don't recall testing a lens that could not be induced to show flare effects, but seldom does a lens produce fewer effects than this one. At f/1.4 with the sun in the corner of the frame, this lens shows almost no flare effects. The effects gradually increase as the aperture is narrowed. This is normal, but less-than-normal is the relatively minor amount of effect at f/16.

There are two lens aberrations that are particularly evident when shooting 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). 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). Lateral CA is an additional aberration apparent in the corners.

The image below is a 100% crop taken from the extreme top-left corner of an EOS 5Ds R frame.

While these stars are not perfect dots, they are not far from being so and these results are good for an f/1.4 lens.

No need to worry about straight lines staying straight with this lens. With practically no geometric distortion, you are safe placing those lines along the edge of the frame as illustrated below.

That this lens can create a strong background blur for its 40mm focal length is easy to discern. Harder is evaluating the bokeh, referring to the quality of that blur. Here are some examples of out-of-focus specular highlights.

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Stopped down 5 stops to f/8, the aperture blades are strongly influencing the bokeh and these results appear decent/normal.

The "CE" results reference the cat's eye bokeh effect, a form of mechanical vignetting, seen in the corners, the top-right in these examples. If you look through a tube at an angle, similar to the light reaching the corner of the frame, the shape of the hole is not round and that is the shape seen here. As the aperture narrows (to f/2.8 with this lens), the entrance pupil size is reduced and the mechanical vignetting absolves with the shapes becoming round.

As the aperture gets narrower, point light sources take on a starburst effect and often the case is that the wider the max aperture of the lens, the stronger the star effect a lens can produce.

When stopped down, this lens's 9-blade aperture produces beautiful, distinct 18-point stars from point light sources.

That is a entertaining lens design. "This lens effectively arranges three FLD (“F” Low Dispersion) glass elements and three SLD (Special Low Dispersion) glass elements to correct axial chromatic aberration and magnification chromatic aberration. Designed for exceptional sharpness at maximum aperture, this lens excels at available light photography. With less than 1% distortion and near non-existent sagittal coma flare, this lens demonstrates consistent optical results featuring both 8K-compatible resolution and a beautiful bokeh." [Sigma]

From an image quality perspective, few lenses compare to this one.

Focusing

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To date, all Art lenses feature Sigma's premium HSM (Hypersonic Motor) AF system.

The 40 Art's AF system has decent speed with the amount of distance change being a significant factor in the experienced AF lock time. Focus at minimum focus distance and then at infinity and you will likely consider the speed rather slow as you wait for the subject to come into focus. Focus on one subject and then on a nearby subject and the lock time will seem fast. As usual, focusing speeds are reduced in low light and some minor autofocus distance adjustments are often made after the initial focus acquisition, increasing the overall AF lock times of even shorter distance adjustments.

This lens focuses quietly with only a quiet shuffling ("shhhh") along with clicks sometimes being heard (if focusing in a quiet environment). Focusing is internal and FTM (Full Time Manual) focusing is supported (unless intentionally disabled using the Sigma Dock).

With an ultra-wide aperture lens being able to produce shallow depth of field at close distances, the AF system's accuracy takes on increased importance – far more importance than autofocus speed to most of us. A mis-focused image heads straight to the trash can most of the time, AF accuracy performance testing is always a high priority for me and experience has taught me to be especially sensitive to third party lens performance in this regard. While some of Sigma's recent lenses have been turning in good AF accuracy for me, to put it bluntly, this one does not. Before going any further, I want to note that sensor-based AF systems, including DSLR live view and the AF systems in mirrorless interchangeable lens cameras, will focus this lens accurately. The conventional DSLR phase detection AF systems I have been utilizing for evaluating this lens have been proving troublesome.

With an ultra-high-resolution Canon EOS 5Ds R behind it, the 40 Art's inconsistent AF performance is magnified. Performance from the Canon EOS-1D X Mark II seems better, but the lower resolution of this imaging sensor probably accounts for most of the difference. On the 1D X II, prefocusing to a distance beyond the subject seemed to produce improved accuracy, but the 1D X II's peripheral AF points seemed to produce reduced accuracy. It is not unusual for Sigma to release lens firmware updates addressing AF issues, so watch for such for this lens.

Focus calibration is also a key to accurate focusing with conventional DSLR phase detection AF systems and the Art lens's compatibility with the Sigma Dock (more later) ensures that this issue, should it exist, can be easily resolved. Cameras with the autofocus microadjustment feature also have the ability to adjust calibration in-camera.

When this lens's focus distances are changed significantly, expect subjects to change size a moderate amount. While this focus breathing attribute is not unusual, photographers intending to use focus stacking techniques involving focus distance adjustment, videographers pulling focus and anyone critically framing a scene should be aware.

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As usual for an Art lens, Sigma provides a focus distance window and a depth of field scale is provided, though f/8 and f/16 are the only marks included.

The 40 Art lens's manual focus ring is significant in size, measuring 2.22" (56.4mm) and easy to find. The focus ring is smooth, has no play and has ideal resistance. Completing this lens's excellent manual focus design is the 128° of rotation that provides for ideal manual focusing precision over the entire focus distance range. This focus ring makes distance adjustments by turning in the same direction as Canon and Sony lenses, opposite that of Nikon lenses.

The Sigma 40mm f/1.4 Art Lens will win no awards for its close focusing capabilities. Wide aperture prime lenses are not often champions in this regard and the 15.7" (400mm) minimum focus distance results in a low 0.15x maximum magnification. Following is a comparison table showing minimum focus distance (MFD) and maximum magnification (MM) for a selection of at least somewhat similar lenses.

Model	Min Focus Distance "(mm)		Max Magnification
Canon EF 35mm f/1.4L II USM Lens	11.0	(280)	0.21x
Canon EF 35mm f/2 IS USM Lens	9.4	(240)	0.24x
Canon EF 40mm f/2.8 STM Lens	11.8	(300)	0.18x
Nikon 35mm f/1.4G AF-S Lens	11.8	(300)	0.20x
Sigma 40mm f/1.4 DG HSM Art Lens	15.7	(400)	0.15x
Sony FE 35mm f/1.4 ZA Lens	11.8	(300)	0.18x
Tamron 35mm f/1.8 Di VC USD Lens	7.9	(200)	0.40x
Tamron 45mm f/1.8 Di VC USD Lens	11.4	(290)	0.29x

Following is a comparison table of all the Sigma full frame prime Art lenses (as of review time).

Sigma 14mm f/1.8 DG HSM Art Lens	10.6	(270)	0.10x
Sigma 20mm f/1.4 DG HSM Art Lens	10.9	(277)	0.14x
Sigma 24mm f/1.4 DG HSM Art Lens	9.8	(250)	0.19x
Sigma 28mm f/1.4 DG HSM Art Lens	11.0	(280)	0.19x
Sigma 35mm f/1.4 DG HSM Art Lens	11.8	(300)	0.19x
Sigma 40mm f/1.4 DG HSM Art Lens	15.7	(400)	0.15x
Sigma 50mm f/1.4 DG HSM Art Lens	15.7	(400)	0.18x
Sigma 70mm f/2.8 DG Macro Art Lens	10.2	(258)	1.00x
Sigma 85mm f/1.4 DG HSM Art Lens	33.5	(850)	0.12x
Sigma 105mm f/1.4 DG HSM Art Lens	39.4	(1000)	0.12x
Sigma 135mm f/1.8 DG HSM Art Lens	34.4	(875)	0.20x

The largest orchid bloom in the minimum focus distance sample image below measures about 2.5" (6.35cm) in width.

A great option for reducing this lens's minimum focus distance is an extension tube. By positioning the lens farther away from the camera, extension tubes permit the lens to focus to a closer distance, increasing maximum magnification, though infinity and long distance focusing are sacrificed. Most are going to find a 12mm extension tube to be perfect for this lens, offering a range of focus distance down to close to the front element of the lens with image quality remaining good. A 25mm extension tube seems a bit strong for this focal length with the range of focus distances being extremely close and image quality taking a bigger hit, especially in the periphery.

This lens is not compatible with Sigma teleconverters, another option commonly used to increase maximum magnification.

Build Quality & Features

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With a strong resemblance showing throughout the line, Sigma's Global Vision series Art lenses all have a classy modern styling, visually featuring various reflectivity levels of black finish and the build quality seems great.

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The 40 Art's exterior features quality Thermally Stable Composite material construction with metal used for the glossy black mount end and of course metal is utilized liberally internally. The barrel diameter changes only slightly throughout the length of the lens, primarily at the focus ring. The sharply-ribbed focus ring feels great and a 180° section of the barrel is mold-ribbed to facilitate grip.

The AF/MF switch, like the rest of the Art lenses, has a white background indicator when in the AF position. The switch is easy to find on its raised switch bank and it is firm with a strong click into position. This lens has some weather sealing, including a rear gasket seal as seen below.

Wide aperture lenses require wide diameter lens elements and, as seen in the design illustration shared earlier in the review, this lens has a lot of densely-arranged elements. Those add up to a noticeable weight for this lens's modest size. Overall, this lens is large and heavy for its class, but it has a comfortable size to use and I haven't minded the weight (though a backpack full of similar lenses would become a burden).

Let's compare:

Model	Weight		Dimensions w/o Hood "()		Filter	Year
Canon EF 35mm f/1.4L II USM Lens	26.8	(760)	3.2 x 4.2	(80.4 x 105.5)	72	2015
Canon EF 35mm f/2 IS USM Lens	11.8	(335)	3.1 x 2.5	(77.9 x 62.6)	67	2012
Canon EF 40mm f/2.8 STM Lens	4.6	(130)	2.7 x 0.9	(68.2 x 22.8)	52	2012
Nikon 35mm f/1.4G AF-S Lens	21.2	(600)	3.3 x 3.5	(83.0 x 89.5)	67	2010
Nikon 35mm f/1.8G AF-S Lens	10.8	(305)	2.8 x 2.8	(72.0 x 71.5)	58	2014
Sigma 40mm f/1.4 DG HSM Art Lens	42.4	(1200)	3.5 x 5.2	(87.8 x 131.0)	82	2018
Sony FE 28mm f/2 Lens	7.1	(200)	2.5 x 2.4	(64.0 x 59.9)	49	2015
Sony FE 35mm f/1.4 ZA Lens	22.2	(630)	3.1 x 4.4	(78.5 x 112.0)	72	2015
Tamron 35mm f/1.8 Di VC USD Lens	16.9	(479)	3.2 x 3.2	(80.4 x 81.3)	67	2015
Tamron 45mm f/1.8 Di VC USD Lens	19.2	(544)	3.2 x 3.6	(80.4 x 91.4)	67	2015

Here is a comparison table of, at review time, all Sigma full frame prime Art lenses.

Model	Weight		Dimensions w/o Hood "()		Filter	Year
Sigma 14mm f/1.8 DG HSM Art Lens	41.3	(1170)	3.8 x 5.0	(95.4 x 126)		2017
Sigma 20mm f/1.4 DG HSM Art Lens	33.5	(950)	3.6 x 5.1	(90.7 x 129.8)		2015
Sigma 24mm f/1.4 DG HSM Art Lens	23.5	(665)	3.3 x 3.6	(85.0 x 90.2)	77	2015
Sigma 28mm f/1.4 DG HSM Art Lens	30.5	(865)	3.3 x 4.2	(82.8 x 107.7)	77	2018
Sigma 35mm f/1.4 DG HSM Art Lens	23.5	(665)	3.0 x 3.7	(77.0 x 94.0)	67	2012
Sigma 40mm f/1.4 DG HSM Art Lens	42.4	(1200)	3.5 x 5.2	(87.8 x 131.0)	82	2018
Sigma 50mm f/1.4 DG HSM Art Lens	28.8	(815)	3.4 x 3.9	(85.4 x 99.9)	77	2014
Sigma 70mm f/2.8 DG Macro Art Lens	18.2	(515)	2.8 x 4.2	(70.8 x 105.8)	49	2018
Sigma 85mm f/1.4 DG HSM Art Lens	39.9	(1130)	3.7 x 5.0	(94.7 x 126.2)	86	2016
Sigma 105mm f/1.4 DG HSM Art Lens	57.9	(1640)	4.6 x 5.2	(115.9 x 131.5)	105	2018
Sigma 135mm f/1.8 DG HSM Art Lens	39.9	(1130)	3.6 x 4.5	(91.4 x 114.9)	82	2017

For many more comparisons, review the complete Sigma 40mm f/1.4 DG HSM Art Lens Specifications using the site's Lens Spec tool.

A comparison photo can greatly help put the sizes into perspective.

Positioned above from left to right are the following lenses:

Sigma 24mm f/1.4 DG HSM Art Lens
Sigma 28mm f/1.4 DG HSM Art Lens
Sigma 35mm f/1.4 DG HSM Art Lens
Sigma 40mm f/1.4 DG HSM Art Lens
Sigma 50mm f/1.4 DG HSM Art 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 28mm f/1.4 DG HSM Art Lens to other lenses. That link is preloaded with a comparison, but also check out this one with a Zeiss Otus 28mm Lens being compared.

The 82mm filters this lens uses are quite large and rather expensive, but this filter size has become popular. Thus, sharing 82mm filters among other lenses in the kit becomes more likely. Sharing 82mm filters with lenses having smaller-than-82mm filter threads is easy with the right step-up filter adapter ring.

This lens does not have a tripod ring available and it is rather front heavy when hanging over a tripod-mounted camera. This is not an issue with a high-quality tripod head, but it can cause lower-strength heads to sag after being tightened.

Like the rest of the Sigma Art lenses, the 40 Art lens arrives with a lens hood, the Sigma LH878-01, included in the box. This hood is large in size, affording a nice amount of protection to the lens from both impact and flare-inducing light. Constructed of strong molded plastic, this hood has a slight amount of flex (good for absorbing impact) and the interior is ribbed to avoid reflections. The push-button release allows easy installation and removal.

New with the 28mm and 40mm Art lens hoods is an increased area of rubberized surface at the back of the hood with the narrow molded-in ribbed area moved toward the front. Note that the rubberized area rapidly showed signs of use, appearing dirty. Welcomed is the push-button release, making installation and removal easy.

Sigma Art lenses come in a nicely padded, double-zippered nylon case. A shoulder strap is provided, but a belt loop is not.

Sigma's lens caps are nice.

Sigma Global Vision and the USB Dock

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Sigma's Global Vision lenses get a classification of "A", "C" or "S", representing a primary Sigma-intended use of "Artistic", "Contemporary" and "Sports". A full description of these categories can be found in the Sigma 35mm f/1.4 Art Lens press release.

Sigma has been introducing some nice lenses in the Global Vision series, but I'm not a fan of the narrow categorization structure. This of course is an "Art" lens and as such, gets an "A" stamped in a classy chrome circle on the lens barrel. Don't limit the lens's use to its letter designation (unless you consider all photography to be "art").

A great feature of the Global Vision lenses is compatibility with the Sigma Dock. The dock, working in conjunction with the Sigma Optimization Pro software, allows the lens's firmware to be updated (bug fixes, compatibility updates, feature enhancements, etc.) and allows precise autofocus calibration at four distances. FTM focusing can also be disabled/controlled via the dock.

Here are some screen captures showing some of the functionality.

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The focus calibration values were set for illustration purposes only.

Price, Value, Compatibility

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Sigma Art lenses are not typically in the realm of "cheap", but they are nearly-always great-value-priced. While the price of this lens is reaching into the mid-tier of lenses overall, it seems like a bargain to me, at least from an optical performance perspective, as the lens compares similarly to or exceeds that of lenses costing far more.

The Sigma 40mm f/1.4 DG HSM Art Lens is available in Canon, Nikon, Sony E and Sigma mounts. This lens qualifies for Sigma's Mount Conversion Service in case you later change your mind. My standard disclaimer: There are potential issues with third party lenses. With the exception of the Sony E mount, Sigma reverse engineers (vs. licenses) manufacturer electronics and algorithms and there is always the potential that a DSLR body might not support a (likely older) third party lens. Usually a lens can be made compatible by the manufacturer via a firmware update, but this cannot be guaranteed. Compatibility with the Sigma USB Dock is risk reducing as Sigma can make dock-compatible lens firmware updates available for easy download. In regards to the Sony mount version of this lens, Sigma states "This product is developed, manufactured and sold based on the specifications of E-mount which was disclosed by Sony Corporation under the license agreement with Sony Corporation." Sigma provides a 1-year limited warranty and Sigma USA provides a limited 3-year warranty extension.

The reviewed Sigma 40mm f/1.4 DG HSM Art Lens in Canon mount was online-retail sourced.

Alternatives

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While there is a large list lenses that could be considered alternatives to the 40mm f/1.4 Art lens, the 40mm prime lens alternatives are extremely limited. I'll start the comparisons section with one of them.

If a Canon-mount lens will work for you, either natively or via an adapter, the Canon EF 40mm f/2.8 STM Lens will give you the same focal length. As the Sigma 40mm f/1.4 Art Lens vs. Canon EF 40mm f/2.8 Lens comparison shows, these lenses are nearly opposites in most other regards. The Canon pancake lens is tiny, ultra-light and inexpensive. The Canon's max aperture is commonly matched by prime lenses. While the Canon lens performs well, the Sigma is sharper at f/1.4 than the Canon is at f/2.8.

A 35mm focal length is not much wider than 40mm and this focal length has many directly-comparable prime lenses, including Sigma's own 35mm f/1.4 DG HSM Art Lens. While the 35 Art has been a highly-regarded lens, the image quality comparison shows the 40 easily besting it. The 40 has slightly less linear distortion and shows modestly less vignetting.

Looking at the specs and measurements, the Sigma 40mm f/1.4 Art Lens compared to the 35mm f/1.4 Art Lens shows the 35 weighing just over 1/2 as much and measuring well under the 40's dimensions. The smaller size means smaller filter threads (67mm vs. 82mm) and the 35 has a higher maximum magnification (0.19x vs. 0.15x). The 40 has a longer focus ring rotation (128° vs. 97°). No one will complain about the 35's considerably lower price tag.

If we can go down to 35mm for a comparison, we can also reasonably move up to 50mm and Sigma's Art lens entry for that focal length is the 50mm f/1.4 DG HSM Art Lens. You will find this comparison quite similar to the last. The 40mm vs. 50mm image quality comparison shows the 40mm as the obviously better lens. The 50 has slightly less linear distortion and shows modestly less vignetting.

Looking at the specs and measurements, the Sigma 40mm f/1.4 Art Lens vs. 50mm f/1.4 Art Lens comparison shows the 50 being considerably lighter and smaller. The 50 has slightly smaller filter threads (77mm vs. 82mm) and a higher maximum magnification (0.18x vs. 0.15x). The 40 has a longer focus ring rotation (128° vs. 92°). Again, no one will complain about the 50's considerably lower price tag.

One of my favorite wide-aperture 35mm lenses is the Canon EF 35mm f/1.4L II USM Lens and this lens is a worthy competitor to the Sigma 40 Art lens. In the image quality comparison at f/1.4, the Canon is a bit sharper in the center of the frame and the Sigma is a bit sharper in the periphery. Which is better depends on the scenario being photographed. Stopped down a couple of stops, the Sigma catches the Canon in the center and retains the periphery advantage. The Sigma shows slightly less flare.

Looking at the specs and measurements, the Sigma 40mm f/1.4 Art Lens vs. Canon EF 35mm f/1.4L II Lens comparison shows, as you are coming to expect, the Canon being smaller and weighing considerably less. The Canon has slightly smaller filter threads (72mm vs. 82mm) and a noticeably-higher maximum magnification (0.21x vs. 0.15x). I have much more confidence in the Canon's AF accuracy when mounted on a DSLR. The Sigma has a modestly-lower price tag.

Nikon's most-similar lens is the Nikon 35mm f/1.4G AF-S Lens. We have yet to test this lens on a high-resolution camera, but the image quality comparison we currently have shows the Sigma obviously being the sharper lens. The Nikon shows modestly less vignetting and the Sigma has less linear distortion.

Looking at the specs and measurements, the Sigma 40mm f/1.4 Art Lens vs. Nikon 35mm f/1.4G Lens comparison shows the Nikon weighing half as much and being much smaller in size. The Nikon has smaller filter threads (67mm vs. 82mm) and a noticeably-higher maximum magnification (0.20x vs. 0.15x). I have more confidence in the Nikon's AF accuracy when mounted on a DSLR. The Sigma has a modestly-lower price tag.

Tamron's closest 40 Art competitor is the Tamron 35mm f/1.8 Di VC USD Lens. The Tamron gives up some max aperture, but it has Vibration Compensation to its advantage and if the subject is motionless, the Tamron exceeds the Sigma's low light capabilities. In this image quality comparison, the Sigma clearly bests the Tamron. The Sigma has slightly less linear distortion.

Or, perhaps Tamron's closest 40 Art competitor is the Tamron 45mm f/1.8 Di VC USD Lens. Again, the Tamron gives up some max aperture, but it has Vibration Compensation to its advantage and if the subject is motionless, the Tamron exceeds the Sigma's low light capabilities. In this image quality comparison, the Sigma outperforms the Tamron. The Tamron has slightly more peripheral shading.

Looking at the specs and measurements, the Sigma 40mm f/1.4 Art Lens vs. Tamron 45mm f/1.8 VC Lens comparison again repeats the story. The Sigma is significantly heavier and larger, has larger filter threads and has a much lower maximum magnification spec. The Tamron is dramatically less expensive.

Not so long ago, I would have said that 2-stops of aperture would have to be given up to get into a zoom lens covering the 40mm focal length, but the recently-prior-introduced Canon RF 28-70mm f/2L USM Lens gives up only 1 stop and the Sigma 24-35mm f/2 DG HSM Art Lens comes close to 40mm with an f/2 aperture. Zoom lenses provide great versatility, but they are not completely advantaged over the primes. Use the site's comparison tools to make your evaluations.

Summary

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Overall, the Sigma 40mm f/1.4 Art lens is remarkable and leading this lens's remarkableness is the image quality. Few lenses have image quality (especially resolution and contrast) as good as this one, few lenses have wide open image quality as good as this one and that few lenses have an aperture as wide as this one makes that last feature even more exceptional. This lens looks as good on the outside as it performs on the inside and the build quality matches.

The 40 Art's size and weight may be considered a downside by some, but though it is relatively large and heavy for its class, the Sigma 40mm f/1.4 Art is in a class of relatively small, light lenses. This lens has a comfortable size for use and it is that not burdensome from a weight perspective. More concerning to me was the DSLR AF accuracy inconsistencies I experienced. Sensor-based AF systems should completely side-step this problem.

That this lens is priced near the slightly-wider focal length prime lenses available from the big camera manufacturers may seem a downside, considering its exceptional image quality, this lens seems value-priced. Value-increasing is that, with superb image quality, a wide f/1.4 aperture and a useful general-purpose focal length, this lens will see a lot of use.