Lens Reviews / Sigma Lenses i Lab tested

30mm	$223 average price

SLRgear Review
10/11/2013
by William Brawley

The Sigma 30mm ƒ/2.8 DN "Art" is an updated version of their well-regarded 30mm ƒ/2.8 prime lens for mirrorless interchangeable lens cameras. This new version gets the Global Vision treatment with an "Art" Series designation and new metal exterior with improved build quality. Optically, though, this new version is practically identical to its predecessor with the same lens element configuration, ƒ/2.8 aperture, minimum focusing distance and maximum magnification.

The Sigma 30mm ƒ/2.8 DN "Art" is available for both Sony E-mount and Micro Four Thirds cameras. We tested the previous model on a Micro Four Thirds camera, but this time around, we were sent the NEX E-mount version, which we tested with our Sony NEX-7. The 30mm ƒ/2.8 DN "Art" lens provides a 45mm (35mm equivalent focal length) angle of view on E-mount cameras and a 60mm angle of view (35mm equivalent focal length) with Micro Four Thirds cameras, due to the difference size sensors.

Like its predecessor, the 30mm ƒ/2.8 DN "Art" lens takes 46mm filters, however it now ships with its own lens hood, which the previous model did not. The new Art-series lens also borrows the same retail price as the older model at just $199.

Note: Although this lens is a Global Vision model, it is not compatible with Sigma's USB Dock tool for configuring lens AF parameters.

Sharpness
As we saw with the old model, the new Sigma 30mm ƒ/2.8 DN "Art" is a very sharp lens, even wide open at ƒ/2.8. There is some corner softness at ƒ/2.8, but overall the effect is minor. When you stop down to ƒ/4, you see much better corner to corner sharpness. Between ƒ/4 and ƒ/5.6 you hit the sweet spot of the lens with optimal sharpness, and you begin to see diffraction-related softness from ƒ/11 and beyond.

Chromatic Aberration
We saw fairly significant chromatic aberration with the previous model, and despite a seemingly identical optical construction, the new Art-series model shows much better control of CA. While the older model averaged around a solid 6/100th of a percent of frame height, the new model cuts the average by more than half, averaging well below 3/100th of a percent of frame height. In fact, the maximum values of CA in the new lens are less than the average values from the old lens throughout all apertures.

Shading (''Vignetting'')
While the 30mm ƒ/2.8 DN "Art" does show some vignetting, it’s not very severe, with the worst at just over half a stop of light loss in the corners at ƒ/2.8. It quickly drops down to a near-constant 1/4-EV of light loss once you stop down to ƒ/5.6 and smaller.

Distortion
Distortion is very well controlled in this new version with a just a bit of barrel distortion (+0.19%), which is a slight improvement over the previous model with its +0.25% barrel distortion.

Autofocus Operation
The Sigma 30mm ƒ/2.8 DN "Art" autofocuses very quickly, and take just under one second to move through it’s focus range. Autofocusing is performed by an inner-focusing linear AF motor and is near-silent. Manual focusing is also available, although there are no focus markings or distance window on the lens and the focus ring rotates indefinitely. The front element does not extend nor does it rotate during focusing, making accessories like circular polarizers easy to use with this lens.

Macro
With a minimum focusing distance just shy of 12-inches at 11.8” and a maximum magnification ratio of just 1:8.1, the Sigma 30mm ƒ/2.8 DN "Art" isn't a great macro performer.

Build Quality and Handling
Improvements in build quality appear to be the primary update to this lens. The lens barrel is now made entirely of metal, while the lens mount remains metal as in the older model. The lens comes in two color options now -- silver, or black with a two-toned metal finish. The focus ring has a polished look, while the rest of the barrel has a brushed metal finish. The new lens hood, however, only comes in black and is made of durable polycarbonate plastic, locking onto the front with a rather satisfying click.

Inside the barrel sit 7 elements in 5 groups with two aspherical molded glass lenses, including one double-sided aspherical lens, that provide correction for chromatic aberrations. The aperture is comprised of seven rounded blades, just like its predecessor, and has a range of ƒ/2.8 to ƒ/22.

Physically, this lens is very compact and lightweight at only 1.6 inches long without the hood, and weighing only 141.2 grams. The lens hood weighs next to nothing at just over 13 grams and adds about 3/4 of an inch in length. This small lens matches the diameter of the NEX-7's lens mount perfectly and balances nicely on this camera (and with other small mirrorless cameras as well). An interesting change from the previous model is that the focus ring is now completely smooth, without any rubberized grip. Thankfully, the focusing ring is very smooth and easy to rotate.

Similar to what we found with the previous version, the lens elements that move when focusing seem a little loose inside the lens when it's not attached to the camera or when the camera is powered down so they make a rattling noise. When you power up the camera, the linear focusing motor is engaged and there is no more rattling.

Alternatives

Sony E 35mm ƒ/1.8 OSS ~$448
Not a wide as the Sigma 30mm, but with a much wider aperture plus Optical SteadyShot image stabilization for better low-light performance, the Sony E-mount 35mm ƒ/1.8 OSS is good alternative, but at more than the double the price of the Sigma.

Sony E 30mm ƒ/3.5 Macro ~$278
Also for the E-mount, Sony's 30mm ƒ/3.5 isn't as sharp in the corners and has a slightly smaller maximum aperture (ƒ/3.5 instead of ƒ/2.8), however the macro performance of the Sony is much better than the Sigma, obviously, and CA and distortion are better as well.

Olympus 25mm ƒ/2.8 Zuiko Digital ~$250
For the Micro Four-Thirds mount, the tiny Olympus 25mm pancake has a clear advantage for users wanting a very compact and lightweight lens while also providing very sharp images. CA is handled well, except when the lens is stopped down significantly, and distortion and vignetting is slightly higher than the Sigma.

Panasonic 25mm ƒ/1.4 ASPH Leica DG SUMMILUX ~$628
On the Panasonic side of things for the Micro Four-Thirds mount, the similar focal length lens is a bit more expensive, but offers the fastest aperture setting of them all, a full two stops faster at ƒ/1.4. Even wide open, this lens is extremely sharp (sharper than the Sigma, except in the corners), and distortion is practically non-existent. CA, however, is somewhat of an issue in the corners.

Conclusion
The Sigma 30mm ƒ/2.8 DN "Art" lens pack quite a punch in such a small package and for such a small price. Although the lens has undergone Sigma’s Global Vision remake, the only major changes over its predecessor seem to be cosmetic. The barrel has been redesigned with metal rather than plastic, and it comes in a black finish as well as a silver.

Despite a seemingly identical lens construction, the new model does better at controlling chromatic aberration and distortion. We tested the old model on the Panasonic G3 with the smaller Micro Four-Thirds sensor, so if the optical construction was identical, we would assume the distortion would be slightly worse when tested on the larger APS-C Sony NEX-7. However this was not the case, leading us to believe that Sigma has made some minor adjustments to the optical construction.

With a small, lightweight design, sharp images and improved optical corrections all for the bargain price of just $200, the 30mm ƒ/2.8 DN "Art" looks to be another solid performer from folks over at Sigma.

Also, check out this Sigma overview video for more information on the Sigma 30mm ƒ/2.8 DN "A" lens.

Product Photos

Sample Photos

View our sample gallery photos over on our Flickr page.

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.