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Sigma 20mm f/1.8 EX DG Aspherical RF

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Reviews Views Date of last review
70 202607 Jul 21, 2012
Recommended By Average Price
87% of reviewers $326.75
Build Quality Rating Price Rating Overall Rating
8.37
8.67
7.8
20_f1_8_1_

Specifications:
Sigma 20mm f1.8 EX DG Aspherical RF is one of several EX Series lenses. It is the first 20mm Super wide-angle lens in the world with a large aperture of F1.8 and angle of view 94.5. It has Macro focusing capability with a minimum focusing distance of 20cm/7.9inches (reproduction ratio 1:4). The iris diaphragm has 9 diaphragm blades to obtain beautiful out of focus image. It incorporates an aspherical lens element in the front as well as rear lens groups, to minimize distortion, spherical aberration and astigmatism. The lens has non-vignetting optical construction, in order to obtain adequate peripheral brightness with open aperture. This is especially desirable for digital cameras. The lens incorporates a rear focus system eliminating front lens rotation, thus allowing the use of a Perfect Hood and easy use of polarizing filters. The lens also incorporates dual-focus mechanism. It is easy to hold the lens, since the focusing ring does not rotate during auto-focus, yet it provides adequate focusing torque of the focusing ring during manual focusing of the lens. The lens materials used in this new lens are lead and arsenic free ecological glass.


 


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Archimago
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Registered: May 14, 2006
Location: Canada
Posts: 0
Review Date: Mar 25, 2007 Recommend? yes | Price paid: $300.00 | Rating: 8 

Pros: Only f1.8 lens in this focal length for most camera systems. Good price. Close focus distance.
Cons:
Sigma EX finish easily rubs off. Sharpness usable but not quite sharp enough for critical work until about f3.5 on my copy. From that point on, quite happy with sharpness. Too easy to accidentally switch AF <-> MF clutch. Large filter size of 82mm.

A quirky lens but I've fallen in love with what it can do! It's fast and capable of shooting at f1.8, and I love the close focusing distance when I purposely want to achieve the perspective distortion effect.

I wish it could be sharper around the f2.8.

As noted by others, the clutch mechanism a bit odd. I really don't mind but wish the friction was a bit tighter to not so easily accidentally trigger the switch.


Mar 25, 2007
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fblucher
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Registered: Nov 8, 2006
Location: Australia
Posts: 0
Review Date: Nov 16, 2006 Recommend? no | Price paid: Not Indicated | Rating: 1 

Pros: Good price, wide aperture, close focusing.
Cons:
My copy was an unusable dud.

Now I'm first to admit that the copy I received was a dud and the store I bought it from was happy to order another one in, but it took 2 months to get the first and it was going to take at least another month to get the second. So I went with the Canon 20mm f2.8, which took 3 days to arrive and works wonderfully.

So I'll review the lens I received.


One of the first shots I took with this, cropped to 25% and minimal USM to compensate. Notice the top right hand corner.
http://finnux.net/tree-25p.jpg


Here's the 100% crop, no sharpening.
http://finnux.net/tree-crop.jpg

For the brief time that I used the lens I found it was built nicely, I really didn't seem an problem with the focus clutch wheel. It would have been a good feature if you didn't have to hit the AF/MF switch as well (of course now I have my first USM lens with full time MF and realise that the sigma method was a joke). I really liked the magnification factor as you could do some fun things with it and the f1.8 would surely have been useful, I'm worried I'll miss it using the Canon 20mm.


I was really concerned with ordering third party glass and I guess my concerns were justified. As you can see the lens was unusable.


Nov 16, 2006
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tanglefoot47
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Registered: Oct 12, 2004
Location: United States
Posts: 14843
Review Date: Oct 5, 2006 Recommend? yes | Price paid: $300.00 | Rating: 9 

Pros: Sharp great colors well built 1.8
Cons:
No HSM

I was a little nervous about getting this lens as I have had some bad luck with Sigma's and some of the reviews in here. But I wanted a wide at least 1.8 and I must said I have been more than happy with this lens. For the money it's hard to beat.

Oct 5, 2006
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versiani
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Registered: Jul 6, 2006
Location: Brazil
Posts: 1
Review Date: Sep 12, 2006 Recommend? yes | Price paid: $400.00 | Rating: 8 

Pros: Sharpness, brightness, focusing, minimum focusing distance, price
Cons:
Filter size, MF/AF switch, lens size

On my camera, it becomes a 32mm. I use it a lot, because of its great sharpness after f/4, and still quite acceptable sharpness for many objectives (e.g. publishing at the web) even at f/1.8. Combining f/1.8 with iso 800 and some post-processing we can make some dreams come true.

But what I really like is the possibility of getting very close to the object and at the same time having the perspective similar to a "normal" lens.


Sep 12, 2006
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MikeSiesel
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Registered: Aug 13, 2006
Location: United States
Posts: 2
Review Date: Sep 1, 2006 Recommend? yes | Price paid: $375.00 | Rating: 5 

Pros: Passes the Purple Fringe Torture Test at f/5.6
Cons:
Dust inside front element, called Sigma Authorized Dealer for RMA twice with no response, and Sigma Customer Service (ahem) recommends sending it to Service Center.

Rating reflects poor service on behalf of dealer and Sigma Photo.

I'm a primary a landscape photographer, and here in Missouri I often have to deal with overcast skies and purple fringing around foliage. In fact I've been doing a fair amount of film to avoid that problem.

Out of the box I put this lens to the test. Shooting straight into the sun on an overcast day with a walnut and a spruce in the foreground.

Even wide open it's not horrible, by f/4 the PF is pretty much gone. Clean at f/5.6. I'm happy with the performance of this lens.

But a closer examination of the lens revealed some dust inside the front element. So I called the next day requesting an RMA. The dealer has assured me twice that an RMA would be sent and I've received none.

You can order a lens online, but their "email is screwed up." I bought the lens (and three more--all clean) but I'm not buying that excuse.

A call to Sigma Customer Service probably says it all. I'm told that the dust won't affect my photos, and that all lenses and cameras get dust inside. Of course as a customer I draw a distinction between my dust and their dust.

Further, I have a several Canon FD lenses that have no dust inside of the lens, and that's after 20-30 years of use.

Of course this is a chance I took buying online.

My recommendation with regards to Sigma lenses is not to buy them sight unseen. If their QA passes dust in the elements, then you might want to take a sharp eye or a loupe along on your shopping trip.


Sep 1, 2006
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morer
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Registered: Oct 26, 2005
Location: Spain
Posts: 0
Review Date: Jul 28, 2006 Recommend? yes | Price paid: Not Indicated | Rating: 9 

Pros: 1,8
Cons:
no hsm

Impresionante en una 350D 32mm de lujo.

Jul 28, 2006
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EltonTeng
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Registered: Mar 20, 2005
Location: United States
Posts: 2614
Review Date: Jun 29, 2006 Recommend? yes | Price paid: $290.00 | Rating: 9 

Pros: Nice build, good optics for the price.
Cons:

This is an excellent fast prime for the price range. Extremely useful for tight quarters or any other place with limited space. The downsides to wide primes such as this is the limited focus range. You are at infinity focus from three feet out.

This is an inherent issue with these lenses and not necessarily a negative.


Jun 29, 2006
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thelund
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Registered: May 24, 2006
Location: Denmark
Posts: 0
Review Date: May 25, 2006 Recommend? yes | Price paid: Not Indicated | Rating: 8 

Pros: Nice build. f/1,8. Sharp when stopped down.
Cons:
Vignetting at f/1,8. A bit soft wide open. Corner purple frining at large apertures.

I bought this lens to replace my EF-S 18-55. I like it so far, the colors are nice, the contrast is good and it is definately sharper (than the 18-55).
It shows obvious vignetting at f/1,8, it dissapears quickly stopping it down a bit though, I'm not noticing any vignetting in my shots at f/2,8. It has purple fringing, only in the corners of high contrast pictures though, nothing in the center. PF noticeable at f/2,8, but not at f/4.
It is a bit soft wide open, not worse than my 18-55 though, at f/5,6 and lower it is very good. Center sharpnes is very good starting at f/2,8.
The focusing mechanism is standard Sigma, that means you have a focusing ring which you can turn on and of, but you ALSO need to turn off AF on a switch... Why not build that mechanism into the focusin ring Sigma? No biggy though.

I like the build, and the lens even comes with a lens hood, this is usual for Sigmas though. Filter diameter is 82mm, which is a bit expenisve (especially polarizing filters).

One thing i REALLY like about this lens though, is the rear focusing mechanism (RF), which means you don't have any moving parts outside of the lens.


May 25, 2006
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sangredetigre
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Registered: May 1, 2006
Location: United States
Posts: 0
Review Date: May 2, 2006 Recommend? yes | Price paid: Not Indicated | Rating: 9 

Pros: SOlid construction & nice finish, fast when you need f1.8, good contrast & shar[pness, little or no distortion.
Cons:
Little, very little, light fall off at corners



May 2, 2006
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tellingthm
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Registered: Jan 26, 2006
Location: United States
Posts: 340
Review Date: Apr 28, 2006 Recommend? yes | Price paid: $300.00 | Rating: 9 

Pros: f/1.8, great iq (w/ a good copy), f/1.8, extremely close mfd, f/1.8
Cons:
lousy af/mf switch, size, terrible af/mf switch, weight, stupid af/mf switch, 82mm filters, awful af/mf switch

First off, I'll admit that mine was an excellent copy.

Now, think about what this lens is- super wide-angle, works on full-frame, and very fast. So it's hard to complain about this lens when there is NOTHING else like it. While I didn't care for the size of this lens compared to my other primes, I understand why it is as big as it is.
The image quality is outstanding; I used it wide open indoors and in low-light all the time. And stopped down, it's even better. Shooting at 20mm (32mm on my 20D) at f/1.8 with a MFD of about seven inches gives this lens another capability that's difficult to find anywhere else.
Build quality was top-notch, what you'd expect from the Sigma EX line. I do wish the front element wasn't so big, because it really looks like there is meaningless space around the outer edges of the glass, and 82mm filters are really expensive.
The only real problem I had with this lens (other than that it wasn't wide enough for me) was the stupid stupid STUPID AF/MF switch. Sigma makes you flip a switch, then slide the focus ring in order to change between modes. It may not sound like a lot, but surprisingly I couldn't get used to it. I'd always forget which mode I was in, and if I was in MF trying to switch to AF I'd have to look in two different places to see what my problem was. Plus, the focus ring is so damn big that it's impossible to pick up the lens without switching its position. Why Sigma couldn't put HSM on this lens, or at least a more simple AF/MF switch, is totally beyond me (and, from what I gather, most people that have used this lens).
That said, this lens does a superb job of what it is designed to do, and if it had HSM, i wouldn't hesitate to give it a perfect 10 rating.


Apr 28, 2006
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shootThis
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Registered: Feb 21, 2006
Location: United States
Posts: 138
Review Date: Mar 24, 2006 Recommend? no | Price paid: $310.00 | Rating: 4 

Pros: Fancy looking, sharp after f4 in expensive
Cons:
useless below 3.5 1.8-2.5 is un-usealbe completely. Weird clutch thing, bad Autofocus

First off 82mm filters are not cheap. Second while the lens is 'inexpensive' it definitely defines; "You get what you pay for". I was really hoping to get a wide, low ap. lens for wedding formals.... this is definitely not it. At 1.8 the autofcus front focused badly, so bad that the pictures were useless, and the bottom of the frame was well focused. Secondly the two step manual focus switching is weird, and as you hold the lens/camera to move around you are constantly switching it between AF/M.

This lens had such potential. It's too bad.


Mar 24, 2006
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canonlight
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Registered: Feb 26, 2006
Location: United States
Posts: 42
Review Date: Feb 27, 2006 Recommend? yes | Price paid: Not Indicated | Rating: 9 

Pros: Great price for 20mm wide and f1.8 speed, Very sharp from f2.5 (useable wide open), Very good colors and contrast, 8" minimum focusing distance a boon, Solid EX build, Grippy and wide MF ring with solid stops at each limit.
Cons:
No HSM, AF speed and noise are "okay", Dual-Focus clutch mechanism takes getting used to, Some may not like the 82mm size thread and overall bulk of lens, Shadow cast with hood on and internal flash (no problems with hood off or external flash).
Feb 27, 2006
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Sarahg
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Registered: Feb 21, 2006
Location: N/A
Posts: 0
Review Date: Feb 21, 2006 Recommend? no | Price paid: $320.00 | Rating: 1 

Pros: None from my persepctive. Might be fine for landscape photography, but the lens was useless to me.
Cons:
Exposure latitude at the high end was awful--detail completely blown out. Colors off, and not very sharp either.

This lens was a big disappointment. I returned it and lost $30 in shipping costs.

I purchased it mainly for concert photography, shooting bands under poor lighting conditions. I have a 20D.

After using the lens for one concert shoot, with very disappointing results, I did an clinical experiment in better light to compare it with my $80 Canon 50 mm 1.8, in terms of exposure latitude.

Sure enough, the cheap Canon lens performed SIGNIFICANTLY better in terms of the detail in areas under direct light. With the sigma lens, much more detail was blown out.

These problems were present under well-lit conditions, but were exacerbated under poor lighting, which for me was the point of getting such a fast lens.

Sharpness was lacking as well, and the focus performance seemed to be inconsistent, though I would have to do further testing to confirm this.

I'm going to save up until I can afford the Canon 24 mm 1.4mm, and until then I will do without. I cannot recommend this lens, even at a quarter the price of the Canon lens.


Feb 21, 2006
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GDBA
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Registered: Nov 15, 2004
Location: Japan
Posts: 1
Review Date: Jan 27, 2006 Recommend? yes | Price paid: $300.00 | Rating: 7 

Pros: Sharp, wide yet fast
Cons:
Incompatibility on 20D with ext. flash, weight, not HSM, finish scratches off easily, 82mm filter size

!! CANON 20D USERS BEWARE !!

This is a fast, sharp lens that worked perfectly on my Digital Rebel.

Then I bought a 20D, and I found an incompatibility between Sigma lenses and Canon bodies.

In low light situations, this lens CANNOT focus correctly. It focuses at infinity if you use the assist beam of an external flash.

So I took this lens back to the Sigma service station in Tokyo along with a Sigma 24-70mm F/2.8 with the same problem, and they told me they had never heard of this incompatibility. I guess they don't read any of the forums. On top of that, they were unable to fix the problem.

So they sent it back having performed only minor calibrations that didn't fix the problem.

This lens is a great value that gives awesome results under most conditions. Just becareful putting it on a 20D in low-light conditions. Same is true for the pre-macro version of the Sigma 24-70mm F/2.8 EX.


Jan 27, 2006
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hauxon
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Registered: Feb 23, 2005
Location: Iceland
Posts: 1820
Review Date: Jan 7, 2006 Recommend? yes | Price paid: $330.00 | Rating: 10 

Pros: It's bright and fast for such a wide lens. Close focusing distance. Solid build. Nice optics, good bokeh, colour etc.
Cons:
82mm filter size. Noisy motor.

This is my favorite lens.

My first impression of the lens was size and weight. It's a bit heavier than my 100m f/ and maybe an inch longer. The front element is huge (82mm) and filters for it a bit expensive. Sigma ships the lens in a nice padded bag and a pedal shaped sun shade.

Before I bought it I had read it was unusably soft wide open but that's not my experience. It's perfectly usable at f/1.8 and stepped down to f/2.2 it's very sharp. At f/2.8 it's as sharp as any of my primes at the same aperature. Note that I've not tested it in the corners but the landscape shot I've made with it look good.

Where this lens really shines is however as an low light indoor lens on a 1.6x cropped body. The cropping factor makes it a 32mm f/1.8 equivalvent lens. For me it serves the same purpose as a 35L would do on a FF body. It's a really nice range for wide indoor shots and fast enough to use with out a flash on most occations.

The lens has a 20cm (8 inches) minimum focusing distance, and that's from the sensor, so you can focus on things almost hitting the front glass. This feature makes you able to do get some interesting "macro" type shots.

The AF motor is noiser than of my other lenses. It's not loud but still an audiable buzz wich can even be heard by your subject. My only other real complaint about this lens is the filter size. An 82mm polarizing filter is expensive! Many complaint about flumsy AF mechanism but it doesn't annoy me that much since I don't MF that often. Turning the AF ring also has much smoother and solid feel than on my Canons. the AF hunts about the same as of my 50/1.4 but hunts more and is slower than my 100/2

Just a great lens and the one that spends most time mounted on my camera.


Jan 7, 2006
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EFM-7
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Registered: Dec 3, 2005
Location: Canada
Posts: 30
Review Date: Dec 4, 2005 Recommend? yes | Price paid: $350.00 | Rating: 7 

Pros: Fast, Cheap, and solid build, excellent control of linear distortion, nice warm colour rendition.
Cons:
Soft(unusable until f/2.2), Awkward rubbery finish, size and weight, AF hunts in low light

Great value for the money,

First thing to note is the build quality, this lens is heavy but it feels solid in the hands. However it has an odd rubbery finish what I'd be afraid to scratch off with my nails or something. It also came with a nice case and a lens hood that fits nice and tight.

First took a shot at f/1.8 LOTS of light fall off, made the image very soft. f/2.0 still the same but marginally better. f/2.2 is a dramatic improvement, still a little soft. f/2.8 much better, now at the point of being usable.

here are some comparison shots I did in a zip file:
http://efm7.24ppqn.com/misc/sigma20mm.zip

I bought this lens for the purpose of nightlife photography, AF is useless in low light without an AF assist beam, so for the most part I ended up shooting with a flash with an AF illuminator, shooting at f/4, which kind of takes away the initial appeal of the lens in the first place (the ability to shoot in low light at big apetures without flash) still a little soft even at higher apertures, maybe I had a bad copy as everyone seems to have different experiences with this lens.

I no longer have this lens as I traded it in for a Canon 24mm f/2.8, which is not as wide or fast but it is sharper and smaller.


Dec 4, 2005
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Sigma 20mm f/1.8 EX DG Aspherical RF

Buy from B&H Photo
Reviews Views Date of last review
70 202607 Jul 21, 2012
Recommended By Average Price
87% of reviewers $326.75
Build Quality Rating Price Rating Overall Rating
8.37
8.67
7.8
20_f1_8_1_


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