Focal length range
AF speed.
Lens hood & carry bag.

Decentered.
Heavy Chromatic aberations.
Poor resolution.
Poor contrast.
You don't get what you pay for.

I shall be brief
The worst lens I've ever had (EOS 30D, EOS 7D)
I had three different copies, tried in 6 months from different distributors
All decentered
One time right side soft + extreme back focus
Two times - left side completely soft, blurred
Stopping down to f/11 or f/16 did not solve the problem

Everything back, changing to Tokina, happy.

Price.
Quality of build.
Quality of image.

None as yet.
I would have liked it to be faster, but I had the choice of spending more and buying the f3.5.

I bought this lens on Ebay without reading any reviews, but based upon my previous experience with the Sigma DP1 which I consider to be a great camera. Sigma stood high in my books.
The Sigma 10/20 was to use on my Nikon 300D.
All my other lenses for this camera are Nikkor, so in a way it was a leap into the unknown.

So, having bought the 10/20 f4.5 I started reading reviews while I waited for it to arrive from UK. To be frank, some of the reviews spun me out, with reports of poor image quality, poor quality control, poor lens cap design etc.etc..

But then the lens arrived, and I've tested it out for the last two weeks on everything from landscapes to architectural interiors.
Mine is a great lens !!
So I guess it means that Sigma have got their act together & have overcome earlier problems ?
I am getting really sharp images when shooting at f8 in all conditions.
Hope this review helps someone.

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I have a Nikkor 10.5 fisheye, which is great for some shots,
but I needed a super wide angle with a lot less distortion. This Sigma 10/20 fills that requirement

Build quality. With my copy, this was definitely the strong point of this lens. I just cannot fault it. It's heavy enough to feel solid in the hand, and light enough to not be a chore to carry around. It feels like it could take a lot of beating, and also gives it an expensive feel.
Image Quality. Well, to an extent anyway. It's not the sharpest lens I have ever used, but I definitely wouldn't say it's bad or even average. Very good centre sharpness, which deteriorates at the corners (though quite heavily at larger apertures).
Price. One of the main reasons I purchased this lens. It is very generously priced, considering it's strengths.
Speed. Since it's a third party lens, I would say it's very good in terms of AF speed. However, in terms of aperture, It's not that good, especially for low light. But, the recently released Sigma 10-20mm f/3.5 lens is a good alternative to this if you want that aperture increase (and want to stick with Sigma. There are larger aperture wide angle lenses available).
'What's in the box'. It comes with a carrying case and lens hood, like many 3rd party lenses do. The lens hood is thick and solid, and case is nicely padded at the top and bottom.

Corner quality wide open. Corner quality at wide apertures is always a problem for lenses (for some it's much less of a problems than for others, but corners are generally weaker than the center), but the distortion on this lens definitely doesn't help much.
Distortion. Not the worst performer in terms of distortion, but it is quite high. In fact, any more and you could probably call it a fish-eye (ok, it's not that bad, but I'm just trying to give an example), so it's probably not the best choice for architectural photography.
Vignetting. At wide apertures, vignetting can be a problem.

To clarify, I am not an expert, more of an advanced amateur, but there was no option for this, and I'm definitely above Intermediate. Also, I live in the UK so price given is in Pound Sterling.

I bought this on eBay from a reputable seller, even after hearing about Sigma's quality control issues. I had considered getting the Canon EF-S 10-22mm, but it was too expensive for my taste, and the Sigma provided everything the same (well, except for 2mm at the long end, but it overlaps nicely with my kit lens). Anyway, being part of Sigma's EX line, I decided to take the plunge and purchased it.

I received it about 3 days later, and, to be frank, I was astounded by it. The build quality is just fantastic. While it is made out of plastic, it is high quality and definitely doesn't feel cheap. It is also reasonably heavy for it's size. I prefer heavy lenses, as they feel more solid in my hand, and I seem to be able to hold them steadier for longer periods (I expect my arms try to compensate too much with the lighter lenses, by thinking the lens weighs more than it does, causing major shake).

I didn't get much of a chance to use it on the first day, so I just took some quick snaps to analyse on my screen. While I wasn't amazed at optical quality (to be fair, it was at 10mm at f/4) it was definitely sharp. The first time I really got to use this lens properly was on a trip to Cornwall. It definitely proved it's worth there, and f/8 seemed to be it's strong point. However, it does take a while to get used to composing images with such a wide field of view, and the fact that the viewfinder I was using was only 95% coverage meant I would continuously get things in the frame that shouldn't have been there (for instance, an image I took of Spinnaker Tower from the base while I was lying down had to be redone about 8 times because I kept getting the top of the Lifeguard safety buoy that was hanging straight above me). That was most likely due to my inexperience at the time.

Autofocus is fast and accurate, just like it should be. Though, not as fast at the Canon 10-22mm I tried on my camera, it got the job done quickly and smoothly.

Customer Service

Didn't have to use Customer service, and probably never will.

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Canon EF-S 10-22mm

Very good image quality. Aberration is visible as with any wide lens, but in practical images (i.e. in images not shot at lab with intentions to find aberrations) not easily seen unless looked for. Build is firm, better than most Canon lenses I see. Comes with a hood. Full-time manual focus in addition to AF, which is a big plus.

Nothing at this price; if it cost more than twice it's price, I'd probably say something about aberrations in lab shoots or about my flash not being able to cover the area under 14mm without the extra plate, but then again, those are usually minor problems. And since it's this cheap, I don't cry---aberrations just teach to think better, shoot better.

Astounding lens in every way, both price and quality. Even if the "big name" lenses bring better quality (how can they?), it's not an excuse for a price that's over double of this lens. And though inexpensive in terms of ultra wide angle lenses, the quality of the images is as good as it gets---to see the lens quality be bad I'd need 10 to 20 more years of experience , and with that I could then also circumvent the possible caveats of this thing..

I didn't dare buying a wide angle lens before I was more or less sure I could get something for the price, but having bought this Sigma lens now I sort of hate myself not buying it earlier already!

Customer Service

Excellent. (plus I got this lens mailed to me in one day)

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Nothing as wide as this, as there's not much available.

Extreme wide angle FOV.
Good if not excellent build quality.
Compact.
Low edge distortion(relative to angle of view).
Low lineal distortion(less than I expected).
Smooth auto focussing.
Cheap price.

Can't really fault this one given it's low cost and good performance.

Using this lens really widens the view for any frustrated APS-C D-SLR user.The width available with this lens is incredible and opens up a whole new world of wide angle photography.
Quality has traditionally been an issue when deciding on OEM lenses or third party but this is one of the better ones that Sigma has produced with good all round performance and relatively low edge distortion for such a wide field of view.
The lens has a good quality, solid feel about it and focuses smoothly on my D200.
A great addition for any APS-C Dslr user.....Must Have!.

Customer Service

None needed-loaner lense.

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Nikon 12-24mm Nikkor.
Nikon 18-35mm Nikkor.

HSM Focusing is quiet and blistering fast.
Manual focus is easy to use. User can be confident of a sharp image.
Composition and distortion is easily achieved in camera position to subject. Not a difficult feat.
Personal like: 77mm lens works with my expensive filters. No vignetting noticed in test shots.

None yet. This lens is built to perform, and as a air traveler, my back pack will provide good protection for this lens, kept in my camera bag, inside my roller board backpack. Nothing weak about this economical performer.

Dollar for dollar this ultra-wide performs. Weight is not an issue, size is super and it easily replaces one of my Zuiko Lenses in my camera bag. With the 10 - 20mm Zoom I have full coverage with my lens sets to 400mm and all easy to pack up and carry.

$499 is a great price for this lens. Little flare issues, sharp, (obviously not as fast as some, but for the money spent - no issue here). Good thing for this user is that it shares my 77mm filters, used on another lens I carry.

Smooth manual focus, and excellent auto-focus. Zoom is smooth and lens performs well on the Olympus E-3. I have read that some users of ultra-wides experience focus ease - I did not experience anything out of the ordinary in that regard.

Can't say enough good things about B&H. They had it in stock and shipped to me in less than a week from order date.

Used with care and conscious of composition issues with a ultra-wide, the focus and distortion control are incredibly easy to deal with. I was able to get very sharp images in medium to low light hand-held. With a tripod - there is nothing this lens can't do, that the more expensive lenses do.

For a person working on a budget, this lens is the way to go. Thanks to Sigma for working out the bugs on this 4/3rds aspect super wide angle lens.

Putting economics before pride - I am very happy with this lens and recommend it as an alternative to more costly ultra-wides. Money well spent!

Customer Service

Hopefully I will never have to go here. I have used SIGMA products for years, and with good care and not chancing a lens to adverse operating environments - I will hopefully never have to deal with customer service.

Must give B&H one more kudo. These folks are GREAT and the PRINTED CATALOG they sent to my home is a staple "Counter Book" in my kitchen. Everything to make a photographer to drool over. Their approach to business is to keep you as a customer. I am glad that I am and I will go back in the future. Give them a try!

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I have 2 other SIGMA lenses and they perform well. With all the money I have saved using SIGMA, I can afford to FLY and TRAVEL more often! :-)

Good color, accuate focusing and just the right size on the D70.
The light fall-off in the corners (have you seen some of the $1,800.00 primes?) is nothing to be concerned about since the main subject is never in the corners!
Allows a range of creative results at extreme close-up that other wide angles cannot duplicate. Flare control is good (and looks good when you use it for effect!). The price is right. It's a good lens to learn wide angle photography with.

I use a glass lens cap and the hood all the time.
I always replace the Sigma front and rear caps with Nikon caps.
There are no other caveats.

I've been in photography since 1958 and have used many lenses and cameras during that time. Wide angle lenses have always been part of my photography.
My first Sigma lens was a 24mm f2.8 MF back in 1976 used on a Nikkormat FT2.
The widest lens I've used (until this Sigma) was an 18mm Nikkor f3.5 (which at $760.00 18 years ago was very costly!). Any shorter lens was out of the question due to the price.
Sigma has changed all that with this lens. The results I get doing interior photography in homes, businesses and industrial settings with a D70 using RAW files, rival the results I used to get with the 18mm Nikkor and my 28mm PC Nikkor lens on film. Straight lines stay straight and any perspective corrections (minor with good shooting practices) can easily be corrected in Photoshop Elements 3, 4 or 5.
The color is consistant with past results on film (and shooting digital means that color can be tweaked to choice quite easily!). The lens has good build quality, smooth manual focusing and quick quiet electronic (HSM) focusing. It's fun to use and stays on one D70 body while the other D70 has the Nikkor 18-70 f3.5-4.5 or the Sigma 24-70 f2.8 DG lens attached (I always keep an 80-200 f2.8 Nikkor nearby to fill out my go-anywhere kit). This lens is worth the $500.00.

Customer Service

None

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Nikkors: 18mm f3.5 MF, AF18-35mm f3.5-4.5, AF18-70mm f3.5-4.5,
MF 25-50mm f4, 28mm f3.5 PC, 24mm f2.8C
Sigma: MF24mm f2.8, AF24-70 f2.8 DG

Wide field of vew
Relative lack of linear distortion
Compact and light
Usable at widest apertures
Excellent stopped down
Can take 77mm filters inc poloriser without significant vignetting

Poor design of lens caps
Needs careful composition to avoid prespective distortion
Watch your feet dont get in the picture if you shoot vertically.

I bought this lens to replace my old 12-24 which was a groundbreaking lens 4 years ago; but Sigma’s new 10-20 promised wider field of view, slightly faster speed, better resolution, smaller size and cheaper too.

I tried one out a few months ago and compared it to the Nikn 10.5 F2.8 there was no contest as I don't personally like fisheye distortion as the Nikon 10.5.

I was impressed enough to buy one. It’s small, quite light looks well made and has a 77mm filter; so can be used with polarizer; the main advantage for me, as its not practical with my old 12-24.

The 2mm wider focal length may not seem much; but at the extreme end of the wide angle scale that can make a much larger difference than one might think. This lens can make ordinary landscapes into dramatic pictures with such a wide field of view.

Considering the wide nature of this lens, Sigma have done an amazing job of controlling linear distortion. The 12-24 was remarkable in that way; but had too be used stopped down to F11 to get the best from it. The 10-20 gives usable results even at F5.6; so by using a 10th second shutter speed; one can use it indoor in darker conditions.

The 10-20 does have some distortion; but it takes the form of a slight mustachio wave; tending towards pin cushion rather than the expected barrel distortion.

The lens needs careful use to reduce the effects of perspective distortion. The extreme perspective distortion causes structures to lean inwards or outwards. This can be exploited to achieve dramatic composition, or be corrected to give a more natural view

For most applications the distortion is hardly an issue; and compared to the serious distortion on Nikons 18-200 VR and the fish eye effect of the Nikon 10.5 F2.8 Sigma have produced an remarkable lens.

Using the lens wide open gives a good image overall; but like many lenses of this type, the corners and edges can look unnaturally stretched. A small amount of chromatic distortion is sometimes present; but considering the angle light has to pass it is through the digital sensor, it is remarkably low.

Customer Service

none

Similar Products Used:

Sigma 12-24 F4.5-5.6
Nikon 17-55 F2.8

Best range of the other wide zooms available
Reasonable sharpness
Extremely "FUN"
Built like a tank
Fast focus

Poorly designed lens cap cannot be removed or placed with the lens hood in place (it needs a center release mechanism)

I wanted a wide angle lens for my D80 and after reading lots of reviews decided to go with a zoom rather than a fish-eye prime. The only real choices are the Nikon and Tokina 12-24s, the Tamron 11-18, and the Sigma 10-20. The Nikon is probably overall the best, but by a very slim margin, and nowhere close to being worth 2X the cost of either of the other 2. The Sigma and Tonika are comparable, but the Tamron is a dog, so I dropped it off the list with the Nikon. I don't think you can go wrong with either the Sigma or Tokina, but 2mm at the wide end is a world of difference, so I put in an order.

This lens quickly became my most "FUN" lens. You can get real creative with it. It is not as sharp as some of my other Nikon lens, but with a little post-processing sharpening the images look very nice even at the 10mm end. Focusing is really fast with the in the lens motor system. I was surprised by the build quality.........excellent!

This lense has two major strong points: sharpness edge to edge and chromatic aberration. The sharpness at 12mm is very good in the center and does not diminish much at all in the image edges, even when shot wide-open. When used wide-open I have noticed that edge softening shows up.It almost looks like a framing effect.It is a very subtle effect. At 18mm, this lens is razor sharp in the edges. Sharpness at 20mm was on par with its performance at 18mm. By trial, error I have found my images are at maximum sharpness between f/8 and f/11.
A very strong + is its ability to handle chromatic aberration (CA). In fact, this lens has almost no visible CA at f/8 and above at 12mm. I'm finding that... at 10mm, there is definitely some CA in the corners of the image, but it can be easily controlled during post processing (PP) in Nikon Capture (if you shoot RAW)
As I see it.This lense has very low distortion. Another " + " of the lense. Apparent across the entire zoom range. At 10mm, there is visible but minor barrel distortion, which becomes pincushion distortion above 15mm. This is not at all unexpected, considering the incredibly wide view at 10mm.
I love the minimum focus distance of 9.4" I have shot clear, detailed images from less than 7 " in some instances. A truely remarkable wide angle lense.
Silent auto focus---> hush hush quiet HSM is excellent.
Light weight (16.6 oz).
The build quality is exceptional.It has a nice reversible bayonet mount hood
I like that it accepts 77mm front filters
I would recommend this lense.

The major weakness is in the lens’ light fall-off characteristics. There is noticeable light fall-off in the corners of this lens, especially wide-open. While light fall-off improved above f/8, it was still apperent if you look carefully enough.

Lense caps (front, rear) I replaced them both with Nikon caps :O)
This lens has a variable aperture design; f/4.0-5.6. Low light performance not good.
For people wanting the best low-light focusing performance, the lack of a constant maximum aperture may be a minor limitation.

Overall, this lens offers outstanding performance at a very reasonable price (about US $500).

I'm using this lense with a Nikon D80,it's a perfect match.It feels totally balnced,The Sigma 10-20mm EX DC lens is a digital only design. The lens has a petal-shaped hood with a reversible bayonet mount. It accepts 77mm front filters.
The focus ring is farthest away from the body, and the front element does not turn when focusing. The manual focus ring is very smooth, with a very viscous feel. The focusing scale goes from 0.8 feet (0.24m) to 3 feet (1m) and then infinity. There are no hyperfocal focus markings on the lense. The zoom ring is very smooth and is marked at 10, 12, 14, 17, and 20mm. The supplied lense cap is a standard “side pinch” lens cap which can be difficult to install or remove with the lens hood in place.

I find myself stopping down to F/8 or lower for landscape images for best performance and using hyperfocal settings.
I've been using this for lense for almost 6 months,It's fun. There is a whole new world from 10-20mm. The images are crisp, clear,by design this lense let's you push the creative envelope.
Shooting architecture @ 20mm has produced some fascinating results.

Customer Service

Not needed