A New 'King of Bokeh'?

The rather remarkable Sigma 50mm ƒ/1.4 EX DG HSM

Years ago, rather unfortunately in some ways, I named the 35mm Summicron-M v.4 as the "King of Bokeh" (bokeh—or boke or boke-aji—meaning out-of-focus [o-o-f] blur). The epithet has taken on a life of its own since then...especially when that lens is for sale somewhere. Erwin rightly scolds me for this (indirectly) in Leica Chronicle.

I was missing part of the story at the time (1997). You see I never shot the lens wide open and very seldomly as little as one stop down. It does have wonderfully coherent blur—from ƒ/5.6 and moderate distances. That brilliant but flawed lens doesn't look its best (in any respect) wide open, or close up. (Lots of falloff, too, which I kind of liked.)

Let's face it, bokeh is not a strong point of Leica lenses, in general*.

Bokeh is one of the few things you can meaningfully look at on the web...although you have to be careful what you're looking at, and you need a very large sample size. People do all sorts of nasty things to their files. Heavy-handed sharpening, for one thing, will step on nice blur.

I've just looked at hundreds and hundreds (I'm not going to 'fess to "thousands," although probably it was...) of pictures made with the Sigma 50mm ƒ/1.4 EX DG HSM, a large and heavy fast normal (or short tele**) prime available in five mounts (Canon, Nikon, Pentax, Sony/Minolta Maxxum, and Sigma) that sells for $450. Maybe 2/3rds of the pictures were showing some degree of o-o-f blur, and in virtually not a single one of those images did I find blur that was anything short of good. Even when stressed—from close up, at every aperture, and with high contrast background objects. And in a great many cases it's outstanding—gentle and coherent.

Example from Argentina

Example from Indonesia

Full-frame example (those heels could hurt you)

Close-up and wide open example

Extreme isolation (narrow plane of focus) example (and he's right about cats)

Example with contrasty background

Example of foreground bokeh

"Smooth Bokeh Test Shot" by Blackriver Images

Remarkable. Surely this lens must have been designed with this quality firmly among the design objectives.

I've seen more interesting bokeh, but usually you pay the price of inconsistency for that. This lens seems like one for those who never want to be surprised by ugliness in the o-o-f. This lens also might be a good one to choose when getting creative about putting important subject information out of focus, as here.

Never seen the lens in person, never used it. And I note that some owners gripe about its AF speed (it's always something). But for gentle bokeh, is there perhaps a new King?

Mike

*...Except the ones you own. Don't kill me.

**On APS-C

P.S. In case you want to share an example of your own, here's the code to put a link or an image into the comments:

Note that the image has to be 470 pixels wide or it will be cut off.

Original contents copyright 2012 by Michael C. Johnston and/or the bylined author. All Rights Reserved. Links in this post may be to our affiliates; sales through affiliate links may benefit this site.

(To see all the comments, click on the "Comments" link below.)
Featured Comments from:

Carsten Bockermann: "Over the years I have tried many 50mm lenses made by Leica, Nikon and Zeiss. In terms of bokeh the 50mm Sigma is clearly the winner, yet there are other 'features' that I don't enjoy that much. First, it's not a fifty. The field of view is noticeably wider than that of, say, a 50mm ƒ/1.4 AF-S Nikkor or the 50mm ƒ/1.4 ZF Zeiss. My guess is that the actual focal length is around 45 or 46mm. While performance at the wider apertures is very good it doesn't really improve when stopping down. At medium apertures the aforementioned lenses offer crisper images. And yet, as I tend to shoot a fifty close to wide open most of the time, this lens is my favorite in that focal length range."

Mark Walker: "Here in the shop where I work I very often show people the Sigma 50,, ƒ/1.4 as a great option over the Nikon or Canon equivalents largely for this reason: the nicer rendering of o-o-f areas, aswell as being a more than adequately sharp lens in the centre at ƒ/1.4. It is one of the few Sigma lenses that I like the look of, image wise, particularly on full frame. (Why do people moan so much about fast lenses being softer at the corners wide open ? You'd think they were going to use it to copy artwork or something)."

Daniel: "I'm sure to be not the only one to mention the Minolta/Sony STF 135mm ƒ/2.8 T4.5. There's even a website dedicated to the lens. It is specifically designed for good bokeh. Probably too good in fact, 'some reviews that hint that the 135 STF creates a slightly unnatural look, exaggerating subjects by rendering the defocusing effect too perfectly' (from the above website).

"I confess that being an owner of this lens I have not made proper use of it; maybe this is the excuse I need to take up more portraiture. On a film camera it was very hard to use owing to it being manual focus and conventional AF screens being rubbish for manual focus (I got an AF9000 with the split screen which works very well). On an SLT or NEX camera (using the LA-EA1), it's a doddle to focus now with magnified live view. You can see some samples on the aforementioned website."

Fletch: "It's an awesome lens... I just got a shock when I clicked on the example from Indonesia and came across my picture :-) "

Mike replies: Small world after all!

Diego: "Among us Sigma afflictionados, the 50mm f/1.4 is good, no question.

"But the lens in the iron mask, the true King of France...er...bokeh, is the Sigma 85mm ƒ/1.4.

"This lens puts the 50mm ƒ/1.4 to shame, in sharpness, focus accuracy, and importantly, quality of out-of-focus blur. Plus, backgrounds get more compressed at 85mm, which leads to more apparent blur. Check out some of the images in the Flickr group for this lens: http://www.flickr.com/groups/1464365@N22/pool/ . OK down off my Sigma pulpit.

"It pains me to admit it, but the honor of bokeh king should go to the Sony/Minolta 135 STF. It is probably the emperor, lord, and master of all things bokeh. This article really should have been about that lens, or at least, mentioned all of the contenders.

"The Nikon 105 ƒ/2 DC and Nikon 135 ƒ/2 DC lenses deserve a mention as well (DC = defocus control)."

Rita Leeds: "In case people are afraid that TOP has already forgotten about the beauty of large depths-of-field, here is a TOP post from just a few months ago: In Defense of Depth.

"I recall browsing the featured comments and reading about how many commenters also thought that bokeh was an annoying fad. I was taken aback at that. I guess it can be annoying if that's all people talk about (and that can certainly be the case a lot), but discounting something only because it happens to be popular doesn't seem like a good idea. Depth-of-field control is about control on both sides, and I don't think people on this site are apt to forget so."

Mike replies: Exactly right, and thanks for adding that, Rita. I personally actually seldom use lots of bokeh in my own photographs—I just like it to look nice when it does show up.

Comments

[Christer]

Surprised you hadn't noticed this lens before, it made quite a splash when it arrived (I think in 2008?). Owned one and could never get it to focus reliably (Sigma calibrated it under warranty which changed it from focusing OK only at 10 feet to focusing OK only at 2-3 feet). The optics are flat out excellent and I wish Sigma had gone the Zeiss route and made it a nice manual focus lens; then I would have kept it. I do miss the images I got out of it, and may try another one some day.

Sigma seems to have a lot of good things going, but tend to bungle up the execution of all their seemingly well engineered products.

[Bill Mitchell]

Any comment about the 30mm version?

[Mike Johnston]

Bill,
I actually owned that one for a while, but found it gave horrendous purple fringing on my then-current K-M 7D, so away it went. (Obviously it wasn't as bad on other cameras.)

Mike

[Ricardo Silva Cordeiro]

I can confirm this having tried several 50mm lenses on the Canon 5D MkII.

I kept a Zeiss 50mm f/1.4 for some years because of it's impressive sharpness and micro-contrast, but then I realised that when I wasn't pixel-peeping I just didn't like the look of the images I was making with it so I sold it for the Sigma.

Apart from it's weigth and size this lens has everything I was looking for: good performance at wide apertures and smooth bokeh. With the Sigma I feel I can get images that are as close to a medium-format look as one can get with a 35mm sensor.

[David S.]

I beg to differ. The Leica 50mm Summilux ASPH and the 75mm Summicron APO ASPH, which are both based on the same design, have bokeh so smooth and creamy it's (paradoxically) kind of distracting:

http://www.flickr.com/photos/speedlet/8094941288/in/photostream

I actually never did get why that 35mm version IV was considered so great, though I spent a lot of time searching for that magical bokeh in other people's pictures. Now I guess I can stop searching.

[josh]

I agree. I love my Sigma 50f1.4 lens' bokeh. I use it and my 135L with a 5d, and I actually tend to prefer the 50mm. If only the focus were more accurate and quick. :/

[Jean-Francois]

It is more expensive than the nikon or canon offering, and not a little bit. Still cheaper than a zeiss but

[Matt]

Pass the onion rings!

[Mike Johnston]

"The Leica 50mm Summilux ASPH and the 75mm Summicron APO ASPH, which are both based on the same design, have bokeh so smooth and creamy it's (paradoxically) kind of distracting"

David,
Yes, those are definite exceptions.

Your example is a very good demonstration of why I don't care for that 75mm, though. The combination of that clinical sharpness that "shouts" for attention, contrasted with the super-smooth bokeh, can look really bizarre, to my eye. Not quite my kinda lens, although that's just a matter of personal taste and obviously other people do, indeed, differ.

Mike

[Mike Johnston]

" I kept a Zeiss 50mm f/1.4 for some years because of it's impressive sharpness and micro-contrast, but then I realised that when I wasn't pixel-peeping I just didn't like the look of the images I was making with it so I sold it"

Ricardo,
Funny, I did the same thing...twice, well over a decade apart.

Mike

[Jayson Merryfield]

I use this lens extensively on Olympus E-5. I'm not sure that I prefer it to the Zuiko 50mm 2.0. It's decidedly soft wide open. That said, it gets a lot of work thrown its way.

Here's a link.

[John Krumm]

I enjoy the 50f2 on 4/3 cameras, though with a 4/3 sensor a longer focal length is better for complete background smothering, if you want that. Here's my daughter with the 50 at 2.2, back when she first started saying "don't take my picture" ...

[thomas hobbes]

agreed, this would be my vote for king as well, though the samyang 85/1.4 puts in an extremely strong showing and only loses due to some annoying loCA in oof regions.

both are a little to boring for general use for me though. i often like a little more "character" in my bokeh (though your 35 cron bokeh king might be a bit much for me). give me a lens with some funky (but gentle) bokeh wide open and well behaved bokeh stopped down a stop or two and i'll be much happier. my favorites in this regard are rokkor 58/1.2 and 40mm cron. for wide open bokeh only i don't think i've ever seen anything i like more than the contax 35/1.4. not for smoothness, it's not that smooth, just for magicalness in the in focus to oof transitions.

and link to a nice thread showing of the lens on FM:
http://www.fredmiranda.com/forum/topic/839374/29

[Steve Jacob]

"Surely this lens must have been designed with this quality firmly among the design objectives."

Yup. Nothing else though. Just that. Every other design parameter was seemingly ignored.

Is it too much to ask for a 50mm fast lens that can do all this but also stop down for landscape services as required?

Besides, put your subject anywhere off center and it becomes part of the bokeh....

[Ernie Van Veen]

I have a Sigma 35mm f1.4, and I love the bokeh it produces on my APS-C camera. But for truly great out-of-focus performance I use my Nikkor-S 55mm f1.2, converted to work (manually) on EOS bodies. Here's an example.

[Bart]

A NEW king? You mean it's BETTER than the Minolta/Sony 135 STF?

[James W.]

The 30 mm Sigma is also pretty good (I used to have one). Is this a strength of Sigma lenses in general?

[Ahmer Inam]

I have had the Sigma since it came out and has worked phenomenally well on my Nikon D300. I primarily use it for portraits but here is an example photo that was taken purely for the "bokeh":

This lens also works great for late night street photography without the use of flash. For example:

Another thing I love about this lens is the micro-contrast that works out really well for B&W conversion. Here are a couple of examples:

... but the lens that I consider the Bokeh king on my Nikon D300 is the trusty old (and fully manual picked up at a yard sale for 50 bucks) Nikkor 105mm f2.5. Here is an examples:

[Owen Cherry]

You're exactly right! I picked up a used copy of this lens at BH Photo during a visit to NYC and fell in love immediately.

[Adam Z.]

I think that my 1936 Leica Summar has pretty great bokeh. But then I'm a sucker for a swirly in OOF areas, and it fills that need quite nicely.

For more traditional creamy bokeh, I'm liking the Planars these days. My ZM 50/2 renders OOF areas beautifully. And while I don't actually have one (yet), from what I've seen, the Canon 50/1.4 LTM does, too.

[John Brewton]

While I have many lenses that produce excellent bokeh, I have to single out the very old, but very good Nikon 105 2.5 Ai.

[Harry Lime]

>Let's face it, bokeh is not a strong point of Leica lenses, in general*.

Blasphemy! Burn the wizard!

:-)

PS:To me the king of Bokeh has been the vintage Summarit 1.5/50 and Summar 2/50. The signature of both of these lenses is so creamy and unique that you can literally spot them on a contact sheet. Interestingly these are probably two of the worst corrected lenses in the Leica line up.

But I agree that the Sigma delivers something special.

I also hear rave bokeh reviews of the Voigtlander 58mm...

[Chris Crawford]

I think if cats could talk, they would. My old cat, Simba, who lived 16 years, was very vocal. He got especially bitchy when his food bowl was empty, or if he hadn't gotten his daily can of tuna.

See my photos of Simba. This cat was so mean that my family's gigantic Great Pyrenees dog was afraid of him. He would attack her and steal her food.

[TimJayFitz]

I have this old MC Rokkor 55m f1.7 that I came with an SRT-101 I bought at a flea market. I shoot it on my Minolta X-700 with black and white film. It has this circular bokeh that almost makes the in focus subject jump out like a 3D photo or something. I'd love to see what it looked like in color on a quality digital SLR.

http://www.flickr.com/photos/timjayfitz/7049663361/

http://www.flickr.com/photos/timjayfitz/7178380656/

[Marc Gibeault]

Somewhat like my favorite, the Pentax M50 1.7, a little better background a little worse color rendition and contrast?

[David Adam Edelstein]

Your asterisk left me laughing so hard my wife had to check if I was OK. I adore my Leica but the glass ain't for everyone.

I also have a Zeiss 50 f/1.4, but I quite like it. Again, not for everyone, but I do specifically like the weirdo bokeh wide open:

http://www.noise-to-signal.com/2010/01/suspended.html
http://www.noise-to-signal.com/2010/03/drip.html

[Zlatko Batistich]

The Canon EF 50mm f/1.2L gets my vote for king of bokeh —
http://www.zlatkobatistich.com/blog/canon-50mm-lens/
That lens has a wonderful blend of sharpness and blur. The Canon EF 85mm f/1.2L II is even better, but I find the 50mm focal length much more useful.

[Roger Moore]

@Bill Mitchell: Any comment about the 30mm version?

I haven't shot with it myself, but the pictures I've seen from the Sigma 30/1.4 seems to have very noticeable cat's eye bokeh at wider apertures. It looks as if the front is vignetting strongly, especially in the corners. I remember some discussion when it came out that it was probably designed for the Foveon 1.7x crop sensors and had problems in the corners of other makers 1.6x and 1.5x crop models.

The Sigma 50/1.4 seems to go to the opposite extreme. It has a huge front element to help avoid vignetting. Unfortunately, that comes at a a big cost in size and weight. It's actually bigger than Canon's 50/1.2 L (though slightly lighter, probably because it has a plastic barrel) and dwarfs other manufacturers 50/1.4 models. Maybe a worthwhile price to pay if it delivers the goods photographically.

[rob]

the sigma 85 and 50 are both very good lenses. i'm not overly concerned about bokeh, but it's certainly there when you need it with these two. great value!

[Eli Burakian]

This is my first 50. Absolutely love it.

[Michael Hultström]

Sigma does produce wonderful bokeh with their fast glass. Two examples from my personal favourite below. Don't mind the puppy, look at the blur:


That's the 300/2.8 though. The King of Bokeh.

[Oskar Ojala]

I must confess that although I like good bokeh when I see it, the vast majority of my photos do not rely on bokeh and thus I don't get around testing it so much...

That said, I like 50's and tend to shoot with razor-sharp Zeiss 50/2 makro, which happens to render a fairly neutral bokeh. But my preference for bokeh is the Nikkor 50/1.2 at full aperture; it's not smooth in the conventional sense, but interesting and pretty and the thin sharp area flows nicely into the unsharp. (I'm not trying the Sigma, I have too many 50 mm lenses already...)

[Peter Croft]

Wow. I love the examples in the comments above. I'm inspired.

As a Pentax K-5 owner I've been toying with the idea of buying a Zeiss 50mm Makro Planar while stocks remain in Pentax mount. But at A$1650 approx, and only MF for that, maybe I should go for the Sigma. It's FAR better value. Would I really see the difference in the Zeiss? I doubt it.

I've got two Sigmas - the 10-20mm and the 120-400mm and I'm very happy with both so far. Thank you, Sigma, for sticking with Pentax mount.

[Peter Croft]

PS: if it's actually around 46mm, that's even better for me. And I'm seriously hoping for a FF Pentax soon, so it becomes a slightly wide walk-around lens. C'mon Pentax.

[Ralph Aichinger]

I think it has not been said yet: The Sigma may very well be designed for bokeh, but it shows. It is truely a beast of a lens for a fifty. It is very huge, heavy and somewhat scary in my opinion.

I've got its smaller cousin, the 30mm f/1.4 for crop, and even that is huge for a normal. Togehter with the supplied shade it almost scares away many human subjects. And it's completely off balance on smaller plastic bodies.

If you consider buying this lens, by all means try it out, otherwise you might be pleasantly surprised by the image quality, but leave it home most of the time nevertheless for weight and size reasons.

[Zvonimir MW Tosic]

Is it true that Summiluxes explode if their aperture is set to f8 or narrower? So one must shoot wide open their Leicas to get that 'characteristic Leica look' or else ...

Photography has become a total dullsville because of that damned bo(ring)hkeh thing. It ticks in the background of every conversation about photography like a silent incendiary device. It seems to be the only subject people ever talk about — apart from equally damned high ISO talk.

Is there a word about the King of the 'everything in focus' land?

[Ed]

Some of my bokeh favorites have already been mentioned, but they include the Rokkor 58/1.2, Canon EF 50/1.0L, and the 178/2.5 aero ektar on a speed graphic. The Minolta 135 STF is nice too.

I think their take on soft focus/bokeh (apodisation?) could probably be DIY-ed into a lens of the user's choosing, with an appropriately sized center filter, as used on wide angle large format lenses, placed in between the lens cells. It seems a similar technique to the imagon idea (though I am sure afficionados will disagree just to be contrarian. )

Ed

[Paddy C]

The Sigma not only has great bokeh (I own the Sony version), but I really like its overall rendering. As Ricardo said above, on FF it does seem to give me a bit of that film MF spatial relationship. I often smile when I look at pictures taken with this lens.

Having said all that, I recently purchase the Zeiss 85/1.4 for Sony Alpha and it's very creamy.

[Titch@]

For me, the kings of bokeh are definitely the Leica Noctilux 50mm 1.0 and the Summilux 75mm 1.4, with outstanding creamy out-of-focus blur areas.
Thank you Mr Mandler.

[Helcio J. Tagliolatto]

"Let's face it, bokeh is not a strong point of Leica lenses, in general"

Johnston, the heretic blasphemer.

[Joe]

No one has mentioned the Nikkor 85mm f/1.4D, the original "cream machine" and it's successor, the G model?

I've got the Sigma 50mm f/1.4 and the bokeh is gorgeous, but my Nikon 50mm lenses (1.4D and 1.8G) are sharper in the center wide open and all the way up to f/2.8, so I'm always on the fence about which one to pack.

[David S.]

Zvronmir has a point.

Back in the era of "f8 and be there", you actually had to contend with multiple subjects within the frame, which called for a sense of composition and mise-en-scene. It was the combination of elements that told the story -- as you see in much of Cartier-Bresson or Elliot Erwitt's work. Everything had to come together just so, and you had to anticipate that moment in advance.

The bokeh fad makes photography easy. Just pick a single subject (a flower, your kid, your cat), throw everything else out of focus, and watch the world admire your silky-smooth bokeh -- which, ultimately means they're admiring your consumer choices, as bokeh is a property of the lens that is bought, not created by the consumer. (Note: I'm as guilty of this as the next guy -- probably more so.)

Of course, because most lenses are pretty much the same at f5.6-f11, "f8 and be there" removes consumerism from the equation -- which, for some people, is the entire point of the exercise.

[Bruce]

For those of you who have succumbed to the glories of micro 4/3, save your pennies for the unbelievable/spectacular/astounding new king..... drum roll..... the 75mm f1.8 Zuiko. It blows absolutely everything out of the water. Try it at a shop near you today on an OM-D with a sales assistant who knows what they're doing. Expensive, yes, (especially with the lens hood!!), but priceless.

[Amin Sabet]

"Let's face it, bokeh is not a strong point of Leica lenses, in general"

Loved this. I'm sick of seeing Leica bokeh described as full of character when identical bokeh from a Cosina Voigtlander lens is called "harsh".

As for the Sigma, it does make for some super smooth bokeh. I've always been struck (or not struck) by that. On the other hand, Lloyd Chambers did a nice bokeh comparison of the Canon 50/1.2L and Sigma 50/1.4, and at matched apertures the Canon was even smoother. The really charming thing about the Sigma is that its bokeh is smooth no matter what the setting, whereas the Canon sometimes needs to be stopped down to f/1.4 :).

[Frank Moskos]

pentax smc 135mm f/2.5. no 50mm can defocus like the 135.

[hugo]

The Sigma 50mm f1.4 was my first and almost only lens on the Sony Alpha900. I chose it essentially for its out-of-focus rendering, and was never disappointed by it.

More examples here.

Sigma is really good at designing prime lenses with lovely bokeh rendering, like the 85/1.4, 30/1.4, 70/2.8 or 28/1.8.

[Kalli]

Until recently, when I eloped with an Olympus, I shot Nikon and my go to lens was the Sigma 30mm f/1.4. A lot of things have been said about that lens, but image wise it did the job for me. Maybe not stellarly, but I'm too lazy to pixel peel (I did a quick comparison once with a Nikkor 28mm f/2.8 AI-S and those few I showed it preferred the Sigma, I preferred the Nikkor, bokeh was not involved, however) and I didn't fancy changing it for the tighter Nikon 35 1.8 when that came out.

I was always pleased with the bokeh from the Sigma 30mm. It's the sort that doesn't much call attention to itself and that's most important to me when discussing bokeh. Sure, there was coma (I think…) at bigger openings, but I didn't much care. The really weird bit was extremely fine circles inside specular (sp?) highlights. I'll link to a couple of samples just for the heck of it, first one should show some coma and the very lame second photo the rings in the specular highlights.

http://flic.kr/p/8VUfBF
http://flickr.com/gp/karlg/633i7a

[Dennis Ng]

Hong Kong owners of this len commented about focusing issue (when aperture stopped a bit from 1.4 but focus is using 1.4, the focus is off say from eye to ear). The 85 does not have this comment (and at least one owner try to look at this as he was burnt by the 50). Hence, this may not be the usual suspect of hard to focus 1.4 lens.

[Tim Bray]

You know, I think that 50mm has a close competitor; its sibling 30mm, which (on my Pentax) is about my fave, see this night street scene:

But, damn cruelly hard to focus wide-open.

[thomas hobbes]

Kalli - those circles inside the specular highlights (often called onion rings) are common in lenses with aspherical elements that are not hand ground (they're a result of the manufacturing process). as somebody else mentioned, the sigma 50/1.4 has them too.

[Iñaki]

I do think that each subject or composition is requiring a certain kind of OOF control or type. Case in point: the oh so venerable 43 1.9 and 50 1.4 FA lenses [yep, guess the manufacturer].

Thing is, I have to know when to use each of them according to the photo I want to take [and I usually don´t take a photo of vegetation].

I am not trying to bash Sigma, at all. Indeed, my experience with them is that their lenses are usually much better than what "connoisseurs" tend to say. Do not have the needed mistique to them [such as the Kiron lenses, or the 70-80´s Vivitar lenses] or the cache of the german manufacturers.

But they have been on the business for quite some time, right?

[Sarge]

Foreground and a little bit of background out-of-focus blur.


Black kettle, black pot, wood fire

Taken with a Voigtlander Heliar 1.8/75mm (112 mm-e) mounted on a Ricoh GXR-M. Manual settings using Ctein's available darkness rule-of-thumb: f/2, 1 second, ISO 400.
WB Auto.

[Kalli]

Thanks, Thomas. Cool to finally get an explanation.

[Sarge]

Hi Mike,

Here's the right-sized photo "Black kettle, black pot, wood fire" for my comment, if it's not too much bother. Sorry and thanks.

[David]

I was photographing some bokeh on a windy day last week..total fail. You can't shoot bokeh in the wind, don't even try. When it's windy, try going for things like garages, or, things made of CONCRETE.

[Anurag Agnihotri]

Mike,
My vote goes to Sigma 85 1.4. Ah.
Will also mention Sony 135 STF.
And Canon 135 F2 L is no slouch either.
I just shot a series of portraits for a European client. When i went to Europe last, was delighted to see these on bill boards and stuff. These were done with a 135 F2 L. Not my kind, but since we are talking about bokeh here:

http://www.flickr.com/photos/agnihot/sets/72157631810676336/

[Ben]

Bokeh king is still the Minolta 135 STF.

Sigma 50 is nothing special, I'm sorry to say.