sigma-19mm-f28ex-dn

Introduction

Sigma 19mm f/2.8 EX DN is the second lens in the new series of lenses for mirrorless cameras that Sigma has introduced in early 2012. The lens currently is available for both NEX as well as mFT cameras and retails at ~$199 (as of April 2012). Along with its 30/2.8 EX DN cousin, the 19mm lens targets entry level market and fills in a niche between Sony's UWA 16/2.8 and 24/1.8 lenses.

The optical construction of the lens consists of 8 elements in 6 groups, with three aspherical surfaces. The build quality is consumerish, with plastic barrel and plastic knurled focusing ring. The lens is fairly compact and light, measuring 60.6x45.7mm (2.4x1.8in) and weighing 140g (4.9oz). The lens accept 46mm screw-in type filters. Aperture is electronically controlled, with min aperture of f/22. The minimum focusing distance is 20cm (7.9in).

 

View 1

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THe manufacturer's box contains the lens, front and rear caps, plastic lens hood and manual/registration cards. Within the scope of this review, the lens was tested on APS-C type Sony NEX-5n and Sony NEX-7 cameras, where its EFOV is 28mm.

Summary

Lens Composition 8 elements in 6 groups
Angular Field 59 degrees (Sony NEX)
Minimum Focus 20cm/7.9in
Focusing Action AF/MF
f-stop Scale f/2.8-f/22, electronic
Filter Size 46mm
Lens Hood Plastic (included)
Weight 140g/4.9oz
Dimensions 60.6x45.7mm/2.4x1.8"
Lens Case Soft pouch (included)
Retail Price $199 (2012)
Depreciation -$50 (2012)


 

Handling

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As the first native WA alternative lens, Sigma 19/2.8 holds a lot of promise. Sitting between the ho-hum Sony 16/2.8 and super-expensive Sony Zeiss 24/1.8 lenses, Sigma offers a lof of appeal to someone who is willing to sacrifice a little bit in FL but save in costs and possibly even get an improvement in quality. Performance of the 16/2.8 lens, particularly on the higher resolution NEX-7 cameras has been a thorny issue for many users, so Sigma can easily corner this side of the market, if its second DN lens shows at least as good performance characteristics as the 30/2.8 EX DN, which we reviewed recently.

Like the 30/2.8 EX DN, Sigma 19/2.8 EX DN is a no frills lens. The look and build of this lens is outright unimpressive on the first look, although the plastic barrel actually can withstand some day to day abuse, including occasional bangs against much harder places. The lens sports a focusing ring, but lacks any other feature commonly found in most SLR and rangefinder lenses, like aperture ring or DOF/distance scale. Sigma incorporated a linear AF motor, which is disengaged when the camera is powered off. This results in some rattling noise when you move the camer/lens combo, but goes away when the camera is turned on and the AF motor is locked in. The lens supports manual focusing as well as manual focus adjust while in DMF and full AF in movie mode. AF operation is slightly slower than with the 30/2.8, but generally the lens focuses on subjects withn 1 to 2 seconds. The usual caveats apply - dimly lit environments and low contrast scenes cause the AF to hunt. Without the DOF/distance scale you would end up relying on the EVF for focusing, which is certainly more convinient in some situations. The focusing ring give about 180 degrees of rotational thrust to those interested in manual focusing this lens.



 

Resolution

Internet forums have been ablaze about the Sigma 19/2.8 lens ever since the first copies started popping up at the doors of eager NEX users. The virtual majority of the users seemed to be fairly satisfied with the imaging quality of the lens, although you could hear complaints once in a while as well. We recently compared Sigma 19mm f/2.8 EX DN to Sony E 16/2.8 only to discuver that Sigma is a stronger, in absolute terms, performer (of course that test needsto be taken with some grain of salt, since we're effectively were comparing lenses of different FL). But everything is obviously relative here - if we were to take Sony's 16mm lens as a benchmark, then Sigma seems to offer a much better quality, albeit at a longer FL. On the other hand, if we were to compare it to the Zeiss 24/1.8, than Sigma's distinction starts to fade away.

If we were to review the lens in isolation (meaning not using any other benchmark whatsover), we could say that performance characteristics of the lens are decent, but not remarkable. The patterns are very similar on both NEX-5n as well as NEX-7. Outstanding center resolution throughout the aperture range and average border performance. This is quite common in most wiide angle lenses (and this is particularly true on NEX-7, which puts significantly more pressure on the lens corners in general) - corners are softer than the center, particularly at wider apertures. Sigma follows this trend, but the absolute difference between center and borders is not as large as with the Sony's 16mm lens - that's why we can claim that Sigma is really an improvement over the otherwise mediocre Sony's UWA.
 

MTF50 (Sony NEX-5n)

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MTF50 (Sony NEX-7)

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LW/PH (Sony NEX-5n)

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LW/PH (Sony NEX-7)

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Of course, arguing about raw MTF50 chart is as useful to a practitioner as a cold shower to a cat. So instead let's take a look at the simplified SQF charts below (just don't forget that there's a reason SQF is called subjective). Here we can see that the lens does not offer much flexibility when it comes to prints, with all print sizes over 17in probably showing some visible quality problems around corners.

 

SQF (Sony NEX-5n)

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SQF (Sony NEX-7)

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Before moving on to the next section, let's first take a look at the crops from the imaging target and then some real life tests. The crops show clear difference in image quality with both NEX-5n as well as NEX-7. Borders at f/2.8 are visibly softer in both cases, sort of confirming what Imatest seems to be complaining about.

 

Sony NEX-5n

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Sony NEX-7

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Eyeballing the results from the real life tests, all done at the infinity with NEX-7 and uncorrected for artifacts, we can observe some minor softness around corners at f/2.8. As we stop down the lens, image quality around corners improves and by f/8 there is no major difference between the center and the corners. Center seems more or less uniform throughout the aperture range. Unfortunately, monitor is not necessarily the best medium for noticing subtle changes and at normal viewing distances some artifacts, even softness around corners, might not be very noticeable - you'd need to blow up the picture to higher magnification to be able to see subtle variation in quality as you stop down the lens from f/2.8. So the bottom line is that unless you are really obsessed at pixel-peeping, or plan to print in large format, you are probably gonna be reasonably happy with the overall quality of images produced by Sigma 19/2.8 DN.
 

Center

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L.L.Corner

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U.R.Corner

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Color & Rendering

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Sigma 19mm f/2.8 EX DN is one of the dozens, if not hundreds, of lenses that don't really have anything unique about the way they render images. There is nothing wrong with that, meaning that users get fairly consistent and predictable performance, albeit without any memorable characteristics. Conventional, boring, predictable, consistent - pick your adjective here.

Like many UWA lenses out there, Sigma 19/2.8 EX DN produces reasonably well saturated colors,with the color gamut that seems to be shifted slightly towards blues. Not exactly cool blue a la Zeiss, but slightly warmer blue. Contrast levels streight out of camera are fairly good - global contrast varies from moderate at wider aperture to moderately high at smaller apertures. Tonal reproduction is average, with balanced range across shadows and mid-tones.

While you can obviously tweak the colors in post-processing and end up with pretty much any look you wish (there are some interesting color profiles out there on the web - some even claim color rendering styles matching Leica and Zeiss lenses), the old good NEX system itself is probably the best option for an average user - just let the built-in image processor optimze colors for you and for the most part you would not be disappointed in this department.

Like many UWAs, Sigma 19/2.8 also shows some CA.. Per Imatest, lateral CA around borders remains pretty constant on both NEX-5n and NEX-7, averaging ~1.5px across the aperture range on NEX-7 and ~1.2px on NEX-5n. This means that you would probay see some color fringing around borders at very high magnification, but the real life impact should not be a major issue.

 

Lateral CA

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DOF & Bokeh

A 19mm lens does not really offer much flexibility in controlling your DOF. With the MFD of 20cm and its max aperture of f/2.8, Sigma 19/2.8 offers DOF of ~1.14cm. Not too bad for the general purposes, but you still are not going to be able to blur the background significantly and achieve a decent level of isolation for subjects, as can be seen in the sample shots below. The OOF rendering of the lens is neutral, with OOF highlightsretaining even illumination and no major signs of longitudinal aberration.
 

DOF @ 30cm

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Flare

Flare control is average in the Sigma 19/2.8 EX DN lens. You can observe that the lens shows some flare and color streaks across the frame in situations when a strong light source (in this case sun) is within the picture frame. Overall however, this is not a terrible result, given the focal length of the lens.

 

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Vignetting

Sigma showed moderate levels of vignetting on NEX-7. At f/2.8 light falloff reaches ~1.5px (uncorrected) but drops to ~0.7px by f/4, making vignetting almost a non-issue.

 

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The camera's built-in vignettign correction reduces vignetting to almost non-existent, but you can also correct it in post-processing - set Photoshop's Vignetting correction to +25 at f/2.8 an to +10 at f/4 to reduce vignetting to minimum.

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Distortion

Distortion is average in this lens - at ~1.4% barrel distortion is not going to cause major issues in real life, although in some cases might be visible around corners.

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Macro

Like the Sony E 16/2.8, Sigma's 19mm lens is not particularly well suited for macro photography. The lens gives you magnification rate of ~0.14x at the MFD, which is not particularly exciting in the macro world. The lens does retain its sharpness in the center throughout the focusing range, so nothing should prevent you from shooting at or close to the MFD, but  ultimately if you're even remotely interested in macro photography, this is not the lens for you.

 

f/2.8 @ MFD

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f/8 @ MFC

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Coma

As can be observed from the image crops below (taken ~1m focusing distance, f/2.8 and f/8 @ 3s exposire), Sigma shows minor degree of coma at f/2.8, which is reduced with stopped down apertures to pretty much non-existent levels

 

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Alternatives

As mentioned earlier in the review, currently there are not that many choices out there for native Sony NEX mount UWA lenses. If you're shooting m43 cameras, you are lucky - there is a ton of opptions available, but Sony users are stuck with either a rather mediocre Sony E 16/2.8 lens or super-expensive Sony Zeiss 24/1.8 lens. A possible solution is to use an Alpha mount UWA lens like Minolta/Sony AF 20/2.8 with an E-LA1/E-LA2 adapter. Or opt for a fish-eye like Samyang 8mm f/3.5 and use a PTLens distortion correction to fix the fish-eye effect. If you don't mind shooting in a manual mode, then a wide selection of rangefinder lenses like Voigtlander Ultra Wide Heliar 12/5.6 and Voigtlander Wide Heliar 15/4.5, or any of the UWA Nikkor Ai/Ai-S lenses should also be considered.

 

Recommendation

As a new entrant into the NEX market segment, Sigma is certainly doing quite well. Sigma 19/2.8 EX DN is the company's second solid offering (the first one was 30/2.8 EX DN) for this system. While the lens might not offer any bells and whistles and does not carry the premium brand name recognition like Zeiss does, Sigma 19/2.8 does a lot of things right - price, resolution, color are all things that, while not absolutely remarkable, are done right in this lens. As one would expect, the lens is not without its weaknesses - some CA, some distortion, some flare and some vignetting, but all of which can either be corrected for or minimized under right circumstances. Bottom line is that this is a fairly good lens in the rather limited selection UWA market for NEX.

 

Sample Images

 

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