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Full review of the Sigma NEX 30mm F/2.8 EX DN lens. 

2012summer/sig30nbox.jpg
Box and contents

 
 
The Sony NEX-C3 was used for this review.  For a better understanding of terms and methods used in this review, go here.
 
The usual center, mid-section and corner crops are located at the very bottom of the page.
 
Restyled in 2013, but the lens performance is the same as the original version reviewed here.
 
  
Introduction.
 

The Sigma NEX 30mm F/2.8 is one of two new Sigma prime lenses (announced in early 2012) designed for use with the Sony NEX and micro 4/3 system, the other lens being a 19mm, F/2.8, also reviewed here.  Both these focal lengths are odd choices by Sigma for APS-C cameras in my opinion, and they don't make any better sense in 4/3 either. 

 

Sigma claims the 30mm F/2.8 EX DN (digital neo) telecentric optical lens has two glass molded aspherical elements, and super multi-layer coatings to reduce flare and ghosting.  Sigma omitted 'OSS' or optical stabilization, probably to keep the price down like Sony did with their NEX 30mm F/3.5 lens.  For some reason the aperture blades are reversed on this lens, meaning the tips of the blades are showing through the front element, it's usually the other way around.

 

Fit and finish are very good.  The lens appears to be clad in high quality plastic with a metal mount.  The lens is made in Japan, and is written in big letters around the front element!!  I guess Sigma is proud they didn't offshore it.  When shaking the lens, it sounds like something is loose inside, and in fact the middle group is just floating around in the center of the lens, but when it gets power from the camera, it stays put; this procedure also takes a couple of seconds, and lengthens the start up time, the owners manual alludes to this.  Avaliable in  Silver or black.

 

Budget lens reality; Sigma basically says in the manual that sending the lens in for repair from water or other damage is a waste; in other words, when the lens fails for whatever reason, unless covered under the warranty, throw it away.

 

Filter size is 46mm, which is a clear nod to Panasonic and Olympus that have numerous micro 4/3 lenses using this size.  Unfortunately, Sony makes no lenses with this filter size, so you might have to get a step-down ring to mount your 49mm filters. 

  
Focusing.  This lens auto-focuses quickly and mostly accurately, and has a very quiet linear focusing motor so it can be used for video.  The front filter ring doesn't turn when focusing, so your polarizers and grads will work great.  The focusing ring is easy to turn, and is damped about right.  If you hold the lens to your ear when the camera is turned on, you can just barely hear it whirring.
 
In the box is the lens, front and rear caps, a padded softcase and owner's manual---no hood, although Sigma says a hood comes with the lens on their website as of this review.  Note; the 19mm hood will not fit on this 30mm lens, there is no way to attach a hood.
 

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Requisite product shots.

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Small front element.
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Back side

 
 
General information and specifications.

Lens

Box contents

Front cap, rear cap, nice padded softcase and user's manual.

Cost

Approximately $199 

Build quality

Very good.

Additional information

This model is made for Sony 'E' mount NEX cameras, and won't work on 'A' mount cameras.  Also available for micro 4/3.

Specifications below

 

Optical configuration

7 elements in 5 groups

Angle of view

50.7˚  Equivalent to about 45mm in full frame (135 format) terms.

Aperture

7 blades, curved

Full frame and APS-C

Sony NEX only.

Depth of field and focus scales?

Nothing.

Minimum focus, image plane to subject

About 11.8"  (300mm)

Minimum focus, end of lens barrel to subject

About 8.9" (226mm) from front of lens barrel.

Hard stop at infinity focus?

No.

Length changes when focusing?

No.

Focus ring turns in AF?

No

Filter size

46mm.

Filter ring rotates?

No

Distance encoder?

Yes
 

Max magnification

1:8.1 or 0.12x 

Min. F/stop

F/22  

Sony teleconverter compatible?

No

Length changes when zooming?

N/A

Dimensions WxL  (my measurements)

2.38" x 1.56"    61mm x 40mm.  

Maximum  extended length (my measurements)

Lens does not extend.                                                 

Weight bare (my scale)

4.7oz, (132g) bare.

 
 
Optical qualities summary.
 
Lens flare/ghosting.  Poor control, see examples below.
 
Light fall-off.  Nothing to worry about.  See samples below.

Color fringing (CA).  Average control.  I see mostly purple along the sides of the image at high contrast edges.  I notice no axial type.
 
Bokeh.  Somewhat smooth.  See crops below.
 
Color.   Seems about the same as Sony lenses.
 
Close-up filter.  Works ok, +4 tested.   
 
Coma.  None.
 
Regular filters: probably don't cause any additional light fall-off, however, I didn't test this as I don't have any 46mm filters.  
 
Filter size.  46mm.  No Sony or Minolta lenses use this size, Sigma used it for the micro 4/3 system which has plenty of lenses already using 46mm.
 
Distortion.  Mild barrel with a slight wave.
 
Distortion example directly below.
 

2012summer/sig30ndis.jpg
Mild barrel distortion

 

The distortion pattern is barrel, with a very slight wave.  Distortion correction sliders are able to almost eliminate it.

 

 

Bokeh samples.

 

           F/2.8

             F/4

2012summer/sig30nbok28.jpg
2012summer/sig30nbok40.jpg

 

Bokeh looks pretty smooth at all subject to background distances, although there is a very slight outer ring at all apertures.

 

 

Light fall-off

 

           F/2.8 Infinity focus

              F/4 infinity focus

2012summer/sig30nvig28.jpg
2012summer/sig30nvig40.jpg

 

There is not much of a problem with light fall-off or 'corner shading' with this lens.  At F/5.6 there is additional brightening of the sides. 

 

 

Flare and Ghosting

 

Heavy magenta flare, sun inside frame, F/11

Flare and green aperture blob, F/5.6

2012summer/sig30ngst1.jpg
2012summer/sig30ngst2.jpg

 
Flare and ghosting control is poor; I see magenta streaks and loss of contrast when the sun is in the image, or just outside the image.  A large green blob shows up too when the sun is towards the center.  Viewing your images on your camera screen may not always show this stuff, it's much more noticeable when you get home and look at the pictures on a large screen.  Use you hand to block the sun from the front element, otherwise you'll be sorry.
 
 
Lateral color fringing.
 

2012summer/sig30ncf.jpg

 
Lateral color fringing is noticeable along the sides of the image, this is about as bad as it gets.  Some cameras will automatically remove this, so you won't see it.  This crop is from the last 700 pixels of the image at the middle left side. 
 

 
 
 
Let's check out the close-focus capabilities of this lens.

The sample shot was taken with the Sony NEX-C3 16.2MP camera, so don't compare it with others that were taken with 12 or 24mp sensor cameras.  The subject is a standard US stamp, 0.87"x 1.0" or 22mm x 25mm.  The shot was taken as close to the subject as focusing allowed; in this case a long 8.9"" (226mm), measured from the front of the lens barrel to the subject.  
 
The Sigma 30mm F/2.8 has a reproduction size of 1:8.1, which is very small.  The close focus shot is pretty sharp with good contrast, but due to the small size, it's boring.
 

2012summer/sig30nmac661.jpg
As close as you can get, F/5.6. No larger size

 
 
Conclusion
 
Overall, the Sigma 30mm F/2.8 EX DN lens is pretty good in optical terms, it's just not a useful combo in my opinion.  Add in the poor flare control, small reproduction size, lack of image stabilization, and this lens really doesn't make a whole lot of sense.  I suppose video shooters may want it if operating at F/2.8 and need this focal length.  
 
Landscapers may notice a little extra sharpness out of the Sigma 30mm F/2.8 if they're currently using the kit 18-55mm lens.  If you need a fast lens for low-light work, consider the Sony 35/1.8 OSS, it's almost the same in focal length, but performs a little better all the way around and is optically stabilized (OSS) for more money.   Also check out the superb CZ 24/1.8, it's expensive, but worth it.
 
Don't get me wrong; the Sigma 30mm F/2.8 EX DN would be fine if this is your focal length, and F/2.8 is fast enough for you.  
 

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Full image showing crop area.

 

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Sample crops from the centers, mid-sections and corners.

 

 

          Center

          Mid-section

             Corner

F/2.8

2012summer/sig30nctr28.jpg
2012summer/sig30nmid28.jpg
2012summer/sig30ncorn28.jpg

F/4

2012summer/sig30nctr40.jpg
2012summer/sig30nmid40.jpg
2012summer/sig30ncorn40.jpg

F/5.6

2012summer/sig30nctr56.jpg
2012summer/sig30nmid56.jpg
2012summer/sig30ncorn56.jpg

F/8

2012summer/sig30nctr80.jpg
2012summer/sig30nmid80.jpg
2012summer/sig30ncorn80.jpg

F/11

2012summer/sig30nctr11.jpg
2012summer/sig30nmid11.jpg
2012summer/sig30ncorn11.jpg

 

The centers look the sharpest at F/2.8, with the best contrast at F/4.  The mid-sections are a bit soft when compared to the sharp centers, but look good at F/5.6.  The corners don't seem to respond well to changes in aperture; they're a little mushy, but are very acceptable at F/8.  Maximum performance seems to be around F/4 in the centers, F/5.6 in the mid-sections, F/8 at the corners.  Landscapers use F/5.6-8 for the best overall image.   

 

Exposure differences are from light fall-off.  Manual focusing used.

 

Please check out the Sigma 30mm F/2.8 EX DN E lens at B&H Photo and help support the site!