Petteri's Pontifications
My musings about photography, mostly.
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El Hombre: Sigma EX 20 mm f/1.8

El Hombre: Sigma EX 20 mm f/1.8

I didn't strictly need the Sigma 20/1.8, since I have Popeye covering that focal length pretty competently, and a couple of bright primes covering low-light more or less OK. However, I wanted it. I wanted it because it was reasonably wide and very bright -- a combination that makes for great hand-holdability and gives marvelous possibilities for available-light situational shooting. So when I saw one in a Chinatown shop in San Francisco, I couldn't resist.

I knew enough of the optic to know what to expect -- excellent performance stopped-down, and a "dreamy" or "soft-focus" look wide-open, that I had judged to be quite sufficient for my available-light needs. I wasn't disappointed, and in fact over the past six months, El Hombre has become one of my favorite lenses. It's not without its quirks, but it punches hard where it counts, and the quirks are pretty small and easy to deal with once you've discovered them.

The mission I had in mind for El Hombre was available-light situational and street shooting, with an idea that I might use it for the occasional landscape too. I haven't shot any real landscapes with it, but have taken it out on the two other tasks, and it's managed them quite well.

El Hombre in person, modeling on an EOS-650. It's a pretty big lens, and the silly hood bayonet makes it look even meaner. Not ideal for discreet situational shooting.

Design and build

Sigma should hire some better usability designers, because the 20/1.8 EX's usability design is beyond quirky. There are a raft of minor design annoyances that I can't believe would have been difficult or expensive to avoid.

I can sort of understand the dual MF/AF switch design (set the switch, then pull or push the ring). There must be some good engineering reason for making it that way, since Tokina does it too. Sigma's version actually works better; at least you don't need to rotate the focus ring to the right spot to click it home. However, I do not understand why they designed it so that the lens automatically clicks into the M position every time you pick it up -- the ring is so wide there's nowhere else to grab it, and picking it up with the front pointing down always flops the ring to M. The focus ring also feels a bit bobbly -- it doesn't shift positively front or back, but also wiggles from side to side.

Joanna reacting to having El Hombre stuck in her face. This lens is not exactly, um, discreet.

The worst has to be the design of the hood bayonet and filter ring, though. There is no reason that I can see to make it maybe 8 mm wider than the lens barrel. This causes the quadruple whammy of an enormous 82 mm filter diameter, a space hog in the camera bag (with the hood reversed, it takes up more space than the much bigger 12-24 Popeye!), a really menacing appearance, and less effective flare protection. I cannot fathom what they were thinking!

The rest is pretty much as is to be expected. The front element is pleasantly flat and easy to clean, there's a nice window with the focus scale and serviceable DOF markings, and the lens balances quite well too.

Fortunately, the usability design is just about the only really bad news about the lens. El Hombre is ugly, but he gets the job done. The lens is built very nicely, with the very professional and reassuring EX fit and finish. The floppy focusing ring doesn't seem to be a build issue as much as a design one.

Shootability

El Hombre has a fast draw and shoots straight, at pistol range anyway. AF is snappy enough (no slower than my Canon non-L primes) and precise enough (my subjective experience is that it's a good deal more precise than the 50 and somewhat more precise than the 35)... up to middle distance. For some reason, once past that pistol range, it goes all over the place. I don't trust AF much for near-infinity shooting anyway, so this isn't that big of a practical issue, but it's good to know that once past a couple of tens of meters, zone focusing is the way to go. Landscapers probably shouldn't be using AF anyway, and at least on my copy it's a doubly bad idea. That broad, smoothly-moving MF ring is there for a reason -- use it when needed.

Yep, it's blurry -- but that's because the shutter speed is really borderline and the kid is moving fast. Focus is right where it should be.

In situational shooting with fairly close-up subjects the AF works very well, down to the lowest hand-holdable light levels, both outdoors and indoors. It's a good deal less fussy to shoot than the 50/1.4 USM, and because of the wider field of view and greater bulk, easier to hand-hold than the 35/2.0. When the going gets tough, El Hombre gets going. It's a lot of fun to shoot in bad conditions. What with the menacing black hat he's wearing, for once darkness actually helps -- people will be a lot less spooked than by daylight.

Auto-focus by candlelight. Can't get much darker than this and expect it to work. No focus-assist used either.

El Hombre doesn't have new-fangled nonsense like HSM, so when he draws, you can hear it. The AF motor is moderately loud; not as loud as my wasp-in-a-matchbox 35/2.0, but pretty loud nevertheless. It's not so loud it would be a problem in most situational shooting, and you only really hear it when it's hunting. With my 35, I've actually come to like the sound of the AF -- the quick "bzzt" gives a nice auditory confirmation that the camera has, in fact, locked focus. When shooting with my 50/1.4 or the Primepipe I used to have, I actually miss it.

Bzzt. Focus acquired. You may shoot now.

Flare

Flare is a much misunderstood and in my opinion much underrated lens characteristic. Most zoom lenses range between bad and terrible when it comes to flare -- the exceptions are the top-grade professional quality zooms that aren't too ambitious in their designs, in particularly when it comes to width or a combination of width and brightness. Most primes range between good and superb. Generally flare performance goes down as the focal length gets shorter and the lenses get brighter -- the big front elements suck in light from all directions, not all of which makes it to the sensor or film. Good flare characteristics are especially important for situational shooting in available light: there will be bright light sources either within the frame or just outside it, and contrasts will often be very big too. After all, available light is whatever is available, and the situation may not happen where the light is ideal.

El Hombre handles flare very well indeed. I had to look very hard through my captures to find any hard evidence of flare effects at all. It took the point-like, difficult Christmas lights in stride, with no ghosting that I could find.

Christmas tree lights. This has potential for ghosting -- the lights reflected from the sensor to the rear element and back again, or doubled through some other internal reflection. I couldn't find any.

Likewise, El Hombre handled potential veiling situations like a Mensch, to mix languages a bit. I had a few severely backlit scenes, where low-key detail was very nicely held despite a part of the image being blown to hell and back again.

No serious veiling on this shot, despite the extremely hot spot at top right. If there's a lot of veiling, by the way, there's often a tell-tale spike at the left edge of the histogram -- the darkest tones captured aren't that dark, and clump there. There was no such spike on the histogram of this or other similar shots I examined.

I did find one flare spot on the frames I examined -- it was on a picture shot moments after the one above. However, I only noticed it after cranking digital exposure compensation up by two stops, and it wasn't too obvious even so.

Find the flare spot! If you know where it is, you can see it. If you don't, I'm not going to tell you. El Hombre is pretty good with flare -- better than the Tokina 17/3.5 even. Very impressive for a lens this bright and this wide.

Sharpness and all that commotion

So El Hombre is pretty good at getting the picture in the box, even if the approach is less than subtle. The next question is, how good is the picture? The short answer is... wide-open, it's noticeably gauzy but salvageable, and stopped-down, it's excellent. For my un-scientific semi-controlled test, I picked something different this time -- a lawn. I figured the high-frequency, low-contrast detail would give an interesting insight into how the lens behaves at different apertures. I did shoot some branches too, just to give a more familiar point of comparison. Unless otherwise indicated, all the crops below are 100% actual pixels, converted with CaptureOne DSLR at default sharpening settings and at most minor tweaks to exposure (all tweaks identical between series).

Reference shot for sharpness -- this is the 35/2.0 at f/5.6, bang in the middle of its sweet spot. It doesn't get much sharper than this with the 10D sensor.

El Hombre at f/8, on a similar subject. To my eye, there's not a whole lot of difference between the two.

OK, so now we have a reference from a more usual test subject, so you know what the f/5.6 shot below represents in terms of more familiar detail. Let's take a look at the lawn. We'll go from f/5.6 (near maximal sharpness) down to f/1.8... and then pull a small post-processing stunt on the f/1.8 crop.

The lawn scene. The crops are from near the center and the lower right corner. Focus is approximately one-quarter of the way into the frame. Incidentally, there seems to be very noticeable field curvature -- the zone of critical sharpness was visibly closer near the edges of the frame.

Lawn at f/5.6, center and corner.

Same at f/4. You seeing what I'm seeing? I'm seeing precious little difference between the two.

Here it is at f/2.8. Still looking plenty sharp to my eye.

Wide-open. Whoops, gauzy. Some people actually buy lenses or filters to get this precise effect. You get it for free. Try it for a portrait one of these days, it might make you new friends -- guaranteed to smooth out skin imperfections. This isn't entirely unlike the 50/1.4 USM, only much more so.

Guess what this is? It's the same center crop from the wide-open frame, only after a pass of unsharp mask at 85%, radius 1.5 pixels, threshold 0. It cleans up the gauze extremely effectively, and in fact makes the picture just about as sharp as at f/5.6. Go Photoshop!

What have we learned? Basically, that the word on the street has got it right: the lens is excellent optically from f/2.8 down, and goes noticeably "dreamy" or "gauzy" wide-open. This sort of effect actually has creative uses, so while it is an aberration and I'm sure Sigma didn't put it in on purpose, it isn't all bad -- and, as demonstrated, it cleans up very nicely with some USM. Unfortunately, in real life, when you're at f/1.8, you'll also most likely be at ISO800 to ISO1600, which means that the USM will punch the noise right up too. There are more sophisticated sharpening techniques that can effectively sharpen up the detail while leaving the already OOF areas (where the noise is more apparent) untouched, so cleaning up images post-exposure is an entirely feasible proposition. It's even ethical -- not even PJ ethics rules forbid this sort of thing, since it's neither putting in nor removing anything that was or wasn't there in the first place.

A real-life wide-open shot before and after the USM treatment. This was at ISO800. I'd say it's entirely acceptable even after USM-ing... but I'm not sure that Selim wouldn't prefer the gauzy version. There's a lot less difference than with the test shots, simply because in real-life shots like this the sharpness will be limited by circumstances more than the lens. After all, who's going to shoot wide-open if they have enough light to stop down a bit?

Finally, a few more crops at various apertures from some more familiar subjects. Note the consistency across the frame and the startling lack of chromatic aberration.

At f/2.8.

At f/4.0.

By the way, when leafing through the several hundred shots I've taken with the 20/1.8, I was yet again struck at how vain some lens testing pursuits are -- for example, the quest for wide-open corner sharpness. Even though I had several hundred wide-open or nearly wide-open real-life shots to look through, I couldn't find a single one where more than one corner was within the field of critical focus -- and they wouldn't have suffered at all even if that corner had been a bit soft too. Of course, with landscapes and such it's another story -- but then, what kind of idiot will shoot a landscape wide-open and expect it to come out sharp?

This kind of idiot, of course. This is wide-open (or almost) with the 50/1.4 (not a crop, the full frame downsampled). To complete the irony, it's one of the few I've actually sold for real money. Luckily the CD cover it went for can make do with a pretty small picture...

At f/8, edge of the frame. This is also nicely illustrative of the difference between "critically sharp" and "within DOF." Everything in this crop is well within DOF, but only the foreground trees are close to what I'd call critically sharp -- the background trees look noticeably murky by comparison. That's because they're far behind the focus distance. (I have a feeling the focus point is a bit in front of even the foreground trees, though; as stated, El Hombre only shoots well at pistol range, and I took this one on AF.) Note the very low amounts of chromatic aberration -- a little bit visible, and most of that on the background less-than-critically focused trees. Another very good performance.

Hey, it does macro!

A 20 mm macro lens is a bit of an oddball, to say the least. To get reasonable magnification, you have to get to really close working distances. Moreover, the wide field of view will make the perspective go notably wobbly. Sigma seems to think so too, since it hasn't put any macro markings on the lens. Nevertheless, El Hombre can get uncomfortably close -- so close he'll have to take off the sombrero to let some light on the subject. Nope, it's not a real macro (a pretty long way from 1:1 or even 2:1) -- but it does do very well for close-ups for what it is. It's roughly similar to the 35/2.0 in this respect -- in fact, the subject magnification at closest focusing distance is durn near the same. However, the working distance on the 35/2.0 is much nicer, the narrower field of view makes for less demanding perspectives, and there appears to be a bit less distortion too. However, a circus poodle walking on two legs isn't remarkable for doing it particularly well; it's remarkable for doing it at all. This is a nice characteristic to keep in mind, for when you happen upon something small you want to remember, although no substitute for a "real" macro solution, if you're inclined towards that sort of thing.

El Hombre squinting up real close. It's just a wee bit more enlargement than with the 35/2.0, but working distance is only a couple of centimeters here. Note also the Uri Geller it pulled on the key -- there is visible barrel distortion at this range. Still, nice to have in a pinch.

The same scene shot with the 35/2.0, also at minimum focusing distance. A bit smaller, a bit straighter lines, a lot easier to shoot. Also, the color is just a tiny bit cooler (I used the same white balance on both) -- El Hombre does have just a hint of Sigma Yellow after all. As stated below, though, in my opinion this isn't enough to matter in practice.

Hardly Any Sigma Yellow, Little Distortion

One more thing: I didn't see noticeable amounts of what's known as "Sigma yellow" on my pictures. I didn't do a side-by-side test against the 50/1.4 (it's quite likely that that test would turn up something), but if there is a color cast to the lens, it's too slight to make a difference for my purposes. El Hombre does come across just a touch warmer in the macro test shots above, but this difference is way to small to matter in real-life shooting. If I got the white balance right, the colors looked neutral enough for me.

As to distortion, El Hombre isn't quite as good as Popeye -- there is some visible barrel distortion. It's not bad enough to be distracting, though, and in architectural stuff it can easily be corrected post-exposure. Not a significant issue in my book.

Conclusion: What's It Good For?

El Hombre really comes into its own when the light gets low. It has clearly the best hand-holdability of the lenses in my stable -- the bright aperture, widish field of view, pretty solid weight, and chunky size guarantee that much. I've gotten pretty usable frames as low as 1/6 second, while 1/15 to 1/20 is usually no problem at all, other than for subject movement. The snappy and positive AF at close to medium distances and down to very low light levels means that it's a very good lens for the job -- when it comes to low-light situational shooting, this is definitely the best lens for the job in my bag. I suspect the Canon 24/1.4L would be even better -- with ring USM and f/1.4, it ought to focus even better, and hand-holdability should be better too, what with the 2/3 stops more brightness but only 4 mm more length. From what I've seen, it also looks a lot sharper wide-open. It costs more than I want to pay for this type of lens, though, and I kinda prefer the wider field of view on the crop factor too.

Looks bright as day. In reality, the lighting is what's usually called "atmospheric" -- meaning normally plumb near impossible to shoot in without a flash. Joanna took this shot, at ISO1600, f/1.8. I hate it when she takes four frames and I take a hundred, and the four best frames in the series are hers.

On the 10D, the perspective at 20 mm is pretty sedate. I wouldn't characterize it as a real wide angle; it feels more like a loose normal. Verticals do converge, but not crazily; the feel between the relationships of foreground and background objects is pretty natural, and faces don't get distorted much even reasonably close up. It has a documentary rather than artistic feel to it. El Hombre is about getting the job done, not prettying it up.

Bring the foreground close enough, and you do get a bit of a wide-angle feel. Poetry reading. Night of the arts, Helsinki, 2004.

For daytime street shooting, El Hombre is a bit too menacing for its own good. There is a real temptation to ask him to take the hat off, and unscrew that hood. This does tone down the looks a good bit, but unfortunately that hood isn't there for show -- it will have a real effect on flare, and moreover the front element is pretty exposed without it. No, I don't have a filter for it -- a good 82 mm UV(0) is insanely expensive, so I'll take my chances on this one. Besides, the flat front element is easy to clean, even in the field. If only I didn't get mud on it when letting the camera hang by the wrist strap when it's ready to shoot...

The Causeway. Helsinki flooded in January 2005, after a bunch of freaky storms.

As stated, I haven't shot any real landscapes with the lens yet. However, from the test shots I've taken, I've no reason to expect anything less than superb performance for this mission -- stopped down to landscape apertures, it delivers a really sharp and aberration-free image all across the frame. However, with at least my copy on my camera, El Hombre seems to be a short gun kind of guy -- meaning, if infinity needs to be sharp, it's advisable not to trust the AF, and go manual instead.

The lens's most noticeable optical quirk is the gauzy look wide-open. While I wouldn't mind if there was less of it, it's a manageable issue. It cleans up very well in post-processing, and may actually be kind of nice on occasion. However, even with the gauziness, in the kind of situation where you would open up to f/1.8 in the first place, image quality holds up more than well enough for 8 x 10 prints, well beyond that with some post-processing. El Hombre has his quirks and isn't the prettiest kid on the block, but is an excellent lens by any standards. What's more, it does something no other Canon-mount lens does -- a solid 20 mm down to f/2.8, and then over a stop more. And it's not even expensive.

However, all that optical goodness and brightness does come at a price -- bulk, intimidation factor, and a couple of minor but annoying usability issues. If low-light performance is not critical, most users would probably be better served by one of the excellent f/4-ish wide zooms, or Canon's own 20/2.8 USM. El Hombre's closest competitor for its "core mission" on the Canon mount would probably be the Canon 24/1.4L. It costs a great deal more, is only a little bit brighter, and has a reputation for soft corners. On the other hand, it does what L lenses do -- holds up solidly right down to f/1.4. Which to pick? Even if money is no object, the choice wouldn't be obvious -- and if money is a consideration, El Hombre will mosey right up to the Canon Kid with a cold glint in its eye.



Slippery when wet. Helsinki Flood of January, 2005