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Full review of the Sigma 10-20mm F/3.5 EX DC HSM lens

Box and contents

The Sony A580 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.
Sigma now offers a high quality, constant aperture, super wide zoom that has the same focal range as the Sigma 10-20mm F/4-5.6 I reviewed a few years ago.  The newer Sigma includes a relatively fast, (and constant) F/3.5 aperture, along with a few other things like Hyper-Sonic Motor (HSM) focusing, a better build quality, and unfortunately, a poor choice 82mm filter ring.  Is it worth upgrading if you already have the older version?  Is it worth the money if you're looking to buy your first super wide zoom?  Read on!  
The Sigma 10-20mm F/3.5 HSM has a very good build quality, with a mix of metal and plastic, and a smooth satin black finish, which is much nicer than the standard sparkly rough black finish used on many of Sigma's other lenses.  This lens sports a focus distance window, (no DOF scale), a rubber ribbed manual focusing ring at the front, a rubber ribbed zoom ring at the back with focal length marks at 10mm, 12mm, 14mm, 17mm and 20mm.  Also included is an AF/MF switch on the left side to turn off the HSM.  Sigma claims the use of a whopping four Asperical elements, two "ELD" and one "SLD" element in the design of the lens.  Most of those abbreviations are marketing spin, and are meant to make you think this lens has what others in the same class may not have.  The lens says "made in Japan."
Zooming causes the lens to extend (raises the front section) to its longest at 10mm; becoming shortest at 14mm, then starts to extend out again at 20mm.


Works on full frame sensor without APS-C size capture on, but clips corners hard between 10-15mm.


The 10-20mm focal length covers the same area as 15-30mm on a 35mm film or full frame digital camera.  

EXIF focal length data reads correctly at the index marks for 10mm, 12mm, 17mm and 20mm.  At the 14mm mark the data reads 15mm, just like the other sigma 10-20mm lens, there is no 14mm in the data at any zoom setting, in fact, I've never seen 14mm in the EXIF data on any super wide zoom, why is that?
In the box is the lens, front and rear caps, plastic petal type hood, soft case, and owner's manual.  
Focusing.  This lens has a relatively quiet motor inside to provide focusing, (similar to Sony's SSM) and doesn't use the slot-screw type system that's typical for older lenses from Minolta and Sony.  All focusing is done internally, so your polarizer and graduated neutral density filters will stay in the position you originally set them in.  The focusing ring turns about 130°, which allows precise manual focusing, although my copy is aggressively damped, so it's too hard to turn with one finger.  Focusing seems pretty accurate, although at longer distances the lens wants to focus slightly past infinity, which can cause some soft shots, depending on temperature or your camera's calibration etc.  Fortunately, manually focusing with a super wide zoom is pretty easy; for most subjects beyond 10' or 20' (4-7m), just set the focus at the infinity mark, stop the aperture down a little and forget it.  At the long end with a wide aperture, you might have to "tweak" that setting a bit.  I rarely use AF on super wide lenses. 


Requisite product shots.

Side shot
Back side
Front element
Sigma X-ray view and incomplete MTF chart

General information and specifications.


Sigma 10-20mm F/3.5 EX DC HSM

Box contents

Front cap, rear cap, hood, nice softcase and users manual.


Approximately $650 

Build quality

Very good.

Additional information

Better built and faster than the original Sigma 10-20mm F/4-5.6  

Specifications below


Optical configuration

13 elements in 10 groups

Angle of view

102˚-64° APS-C 


7 blades, curved

Full frame and APS-C

Made for APS-C cameras only, but will work on full frame using APS-C size capture.

Depth of field and focus scales?

Focus distance scale in window.

Minimum focus, image plane to subject

About 9.5"  (240mm)

Minimum focus, end of lens barrel to subject

About 3.75"  (95mm) 

Hard stop at infinity focus?


Length changes when focusing?


Focus ring turns in AF?


Filter size

82mm, bad choice by Sigma, as they're expensive.

Filter ring rotates?


Distance encoder?


Max magnification

1:6.6 or 0.15x

Min. F/stop


Sony teleconverter compatible?


Length changes when zooming?


Dimensions WxL  (my measurements)

3.43" x 3.47"   87mm x 88mm, widest at filter ring.

Maximum  extended length (my measurements)

3.6"  (92mm) longest at 10mm.                                           

Weight bare (my scale)

18.3oz  (520g) bare

Optical qualities summary.
Lens flare/ghosting.  Very good control.  I sometimes see a small green blob in the image when the sun or bright lights are near the edges, or inside the frame, see examples below.
Light fall-off.  moderate amounts at F/3.5, but it makes a smooth transition from the corners to the center.  See samples below.

Color fringing (CA).  Lateral color fringing control is below average for a super wide zoom from the twenty first century.  I see magenta and cyan along the edges of the image at all focal lengths.  Axial color fringing (occurs all over) is noticeable at wide apertures, but stopping down get rid of this.  See example farther down the page.  
Bokeh.  Smooth at F/3.5, but fairly harsh at other apertures, see examples below.
Color.   Seems about the same as Sony lenses.
Close up filter.  N/A    
Coma.  A tiny bit at F/3.5, 10mm, gone at F/4.5.
Regular filters cause no additional light fall-off.  
Filter size.  82mm, and a poor choice by Sigma as this size is not used on very many lenses, (none for Sony), and they're expensive as compared to the normal 77mm size you'd find on a super wide-angle lens.  You can use 77mm filters with caution, see the light fall-off samples for more info.
Distortion.  Minor to moderate barrel and pincushion, depending on focal length, see samples below.

Moderate barrel distortion at 10mm
Minor barrel distortion at 12mm.
Minor pincushion distortion at 16mm.
Moderate pincushion distortion at 20mm.


The distortion produced by this lens at 10mm is somewhat simple in that it doesn't have "mustache" type like the similar, but less expensive Sigma 10-20mm model; however, it does seem to have a "flat" section in the middle at all focal lengths, so it isn't so easy to completely correct in post processing, although the distortion isn't very noticeable unless you're shooting straight lines along the edges of the image, such as architectural or interior subjects.  Distortion is almost flat at 14mm.



Bokeh samples.


          10mm   F/3.5

            10mm   F/5.6


           20mm  F/3.5

             20mm  F/5.6



Bokeh looks pretty smooth at wide apertures, but the aperture shape and slight ring shows up when stopped down smaller than F/4.5.  It's hard to get any background blur (especially at 10mm!) unless you focus on something very close.  Bokeh is out of focus highlight blur, and not simply how far out of focus the background is.

Light fall-off samples.

           10mm  F/3.5



           20mm  F/3.5

              20mm  F/5.6


           10mm  F/3.5  Close focus

              10mm  F/3.5, with 77mm filter



The light fall-off signature transitions from dark to light gradually and smoothly, so it isn't very noticeable.  Close focus shows a somewhat hard transition, but that's at maximum reproduction range.


It is possible to use 77mm filters on this lens at all focal lengths if you hold the filter up directly against the lens face.  If you use an 82mm-77mm step-down ring, you'll see clipped corners at 10mm-12mm, but the rest of the focal range is clear.


Full image light fall-off.




This image (showing shadowy person with long legs and huge head) illustrates real world light fall-off from 10mm, F/3.5.  It doesn't bother me.  The soft spot (cactus) on the left side is mostly caused by being out of the focus range.  Specs, 10mm, F/3.5, ISO 200, 1/3200sec, +0.30eV.



Flare and  ghosting.


Small green dot at top center, with sun out of shot.  10mm, F/5.6.

Nothing at 20mm, F/5.6.


Ghosting control is generally very good.  When the sun is in, or near the image, a green spot or amber/orange colored blob might be visible, but it doesn't happen much.  When stopped down hard, like F/11-22, ghosting is much more noticeable.  Use your hand to block bright light sources when they're out of the image, even if the hood is on, especially at the super wide end.
Coma samples

10mm, F/3.5.

10mm, F/4.5.


Coma takes the form of weird, smeared blobs at points of light in the corners of the image, especially in super wide angle lenses.  The Christmas tree lights here show just a small amount of coma at 10mm, but it clears up quickly by stopping down the aperture.  100% crops from the far corners.

Let's check out the macro capabilities of this lens.

The sample shot was taken with the Sony A 580 16.2MP camera, so don't compare it with some others that were taken with the 12.2mp A700.  The subject is a standard US stamp, 0.87"x 1.0" or 22mm x 25mm.  Also, note the macro shot was taken as close to the subject as focusing allowed; in this case a very short 3.75" (95mm), measured from the front of the lens barrel to the subject.  
I see a somewhat small (0.15x), but sharp stamp shot, (click for cropped image, 314k), all the way from F/3.5-F/8.  As a side note; the "1996" on the bottom left of the stamp measures a mere 1mm wide.  

As close as you can get, F/4.



Lateral color fringing.


Color fringing crop from far right side, 10mm, F/5.6


This crop is from the last 700 pixels on the middle right side.  I see some pretty heavy magenta and cyan color fringing along the tree branches, but is mostly removable in RAW using CA sliders.





The Sigma 10-20mm F/3.5 super wide-angle zoom has some really nice qualities, but isn't perfect; then again, what lens is?  If you own the slower and cheaper Sigma 10-20mm F/4-5.6, should you upgrade?  Would this be a good lens for Real Estate or interior photography? 


On the plus side for the upgraded Sigma is the excellent build quality, it looks and feels like an expensive lens.  It also has a constant, relatively fast F/3.5 aperture, and is sharp in the centers at that aperture, at all focal lengths.  The mid-sections are pretty sharp at F/5.6, although not super sharp like the centers.  On the down side; the corners are soft at wide apertures at all focal lengths, but do sharpen up to acceptable levels around F/5.6-8 depending on zoom length.  Another issue is color fringing, it's strong, and noticeable along the sides of the image (at all focal lengths), especially if you look at your pictures fully enlarged on your computer screen.  A fix for this is to shoot in RAW and fix it with CA (chromatic aberrations) sliders, if you have that feature in your photo editing software. 


The HSM focusing system is almost silent, and mostly accurate, but not really any better than the old slot/screw system.  The last thing I'd like to mention is distortion, this new Sigma doesn't have the annoying "mustache" type of distortion at 10mm that the old one has, and that makes it easier to fix.  If you shoot mainly between 12-20mm, there isn't much difference.


Now to answer the questions in the first paragraph; people that already own the Sigma 10-20mm F/4-5.6 should ask themselves, do I need more light gathering ability at the longer focal lengths?  If not, there is no reason to upgrade.  Yes, the new lens is sharper in the centers, especially at 10mm, but is that the length you use the most, and is that the most important quality you're looking for?  If you don't already own a super wide-angle zoom, and are considering the two Sigma's, I'd probably go with the new version, as it isn't much more money, and it offers a stop and a third of light at the long end, that's important if you shoot in low light without a tripod.


People getting into Real Estate photography will be happy with this lens, however, stay away from the super-wide end, that's showing way too much for interior shots, and will be nearly impossible to light properly. 


Bottom line; the Sigma 10-20mm F/3.5 is a very good choice for a super wide zoom, if you're worried about the soft corners, simply use a little less focal length, and crop the extreme corners out.  I almost always straighten and crop my images a little bit; most people do, and that would eliminate the soft corners.






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



















The 10mm centers look pretty sharp wide open at F/3.5, but stopping down to F/4 helps bring up the contrast.  The mid-sections sharpen up nicely at F/5.6, but never quite equal the centers.  The corners sharpen up reasonably well at F/5.6, although no match for the centers or mid-sections.  The softness at the corners transitions quickly, so a little bit of cropping can remove the blurry extreme corner areas.  Distance from camera to subject is about 25' (7.5m).





















At 16mm, the centers are pretty sharp at all apertures, but the mid-sections require another stop or so to peak, and then look about the same as the centers, that's good.  The corners look awful at F/3.5-4, but do respond positively when closing the aperture, and by F/8 seem acceptable.  The subject is two large rocks with a small pot placed next to them.  Distance from camera to subject is about 35' (10.5m).




















Performance at 20mm looks about the same as 16mm, which is good except for the extreme corners.  The tree branches are waving in the breeze, that's why the shadows are different.  Distance from camera to subject; about 70' (21m).


Please check out the Sigma 10-20mm F/3.5 EX DC HSM at B&H Photo and help support the site!