Wednesday, May 30, 2012

Sigma 50 1.4 review

I had lunch the other day with the Most Interesting Man in the World, and that's what he told me.  Hit the jump for our review.
Sigma 50 1.4 on a D3

I got a full frame camera mostly because I wanted more control over the depth of field.  Call me shallow.  I first used the D3 with the Tamron 28-105 2.8.  The shallow dof that I wanted was definitely there, even at 28mm.  However, I wanted an even shallower DOF at conversational distances (i.e. not with a telephoto), so I started thinking of getting a fast 50 and/or an 85.

Eventually I decided against an 85 for reasons I'll discuss next time.  Meanwhile you know how cheap I can be, so naturally my first instinct was to look at the Nikon 50 1.8D, the cheapest fast 50 for Nikon.  The problem with the 50 1.8D is that the bokeh is not very good.  I'm not a bokeh connoisseur, but I figured if I was getting a lens because of the shallow depth of field, I may as well get one with nice bokeh.  So I considered the 50 1.8G and the 50 1.4G, both of which have better bokeh than the 50 1.4D and 50 1.8D.

As I did more research though, I saw side-by-side comparisons with the Sigma 50 1.4.  I had never considered the Sigma previously because it actually costs more than even the Nikon 50 1.4G.  However, I could not deny that in comparisons, it had the smoothest bokeh.

I read up on reviews of the Sigma.  Photozone wrote that it is sharp at the center but soft at the "borders." I found this discouraging but I also checked out DPReview's lens comparison tool, which shows the actual size of the zone that is sharp and the part that is not sharp. 

It showed that the Sigma is sharper than the Nikon 50 1.4G at wide apertures except at what I would consider the edges.  With this kind of lens, I don't consider edge sharpness important insofar as I mostly take photos of people, not landscapes.  In addition, I was planning to use this lens wide open anyway, which meant that unless I was focusing on a subject at the extreme edges of the frame, anything at the edge would most likely be outside the depth of field anyway, making any discussion of sharpness moot.  Reviews also agreed that it has low chromatic aberration and low vignetting.

So I got the Sigma, dubbed by some, to the dismay of Leica fans, as the Sigmalux.

Before we talk about the Sigmalux, let's talk about normal primes in general.

Almost all my lenses are and have been zoom lenses.  When I used the Sigma 50, I initially found it very limiting.  Sometimes it's too wide, and sometimes it's too long.  But my coauthor mshafik wisely suggested to stick it out.  After using it for a while and looking at the shots as a whole, I found that I got many kinds of shots from it, from shots of locations, to environmental portraits, to headshots, to details of objects.  Pretty much the same variety of shots that I get from a standard zoom.

shot of a location

environmental portrait
3/4 length portrait


So, I believe the normal prime is an alternative to the do-it-all 24-70.  You may want to know that Henri-Cartier Bresson shot most of his photos with a 50mm lens.  True, a 50mm doesn't have the same control over focal length that the 24-70 does, but in return I get better control over DOF, better sharpness (at f/2.8) and a higher shutter speed if I need it.  A reasonable trade IMO.

Moreover, after I resumed using my standard zoom again, I found that I was using it at 50mm more often.  What happened?  Here's what I figured out: I had been consciously choosing the focal length in determining my composition (considering the perspective, etc.).  That's good practice.  However, sometimes a normal perspective, neither exaggerated nor compressed, is exactly what I want.  This is not the same as passively disregarding the effect of focal length and "zooming with your feet" (which is faulty advice).  Instead, sometimes I consciously choose a normal focal length, for example when I don't want to distract the viewer with the focal length and instead want to invite the viewer to look at other aspects of the photograph such as its substance or lighting or depth of field or any other aspect.

As if the Sigma's versatility weren't enough, as a bonus, I can use the Sigma on an APS-C body as a short portrait lens with an equivalent focal length of 75mm.  It's shorter than what I would like for a portrait lens but I can get upper body portraits or even head-and-shoulders portraits with this focal length, especially if I want to make the background or environment a significant element of the composition.

Sigma on APS-C (Fuji S5)
Sigma on APS-C (D70)


The 50 1.4 is part of Sigma's EX line of professional lenses, meaning it has a higher build quality than their non-EX lenses.  Like Sigma's EX lenses, it has a matte crinkle finish.  It does feel very solidly built to me, but to be honest I'm not very particular about that sort of thing and am more concerned with performance.

The most distinctive physical quality of the 50 1.4 is probably its size.  It is quite large for a nifty fifty.  It is about the same size as the Nikon 85 1.4D.  Size comparison here.  The filter size is 77mm -- huge for a 50 1.4 lens -- but very convenient because it is the same size as several of Canon's and Nikon's better lenses (e.g., 24-70, 70-200).


A.  Bokeh
Bokeh is the quality of the out of focus areas.  It is subjective but most people prefer a smooth-looking bokeh (words such as "creamy" are often used to describe the bokeh of lenses such as the Nikon 85 1.4).
How smooth is the bokeh of the Sigma?  It's so smooth that if you rubbed a baby's butt on it, the bokeh would get scratched.  Yes, the Sigma has one of the smoothest, if not the smoothest, bokeh for a 50mm f/1.4 lens.
hypnotic bokeh

I also noticed that in a few shots, the bokeh seems to form a circular pattern around the middle of the frame, sometimes called "swirly bokeh".  I think it is a cool effect for portraits, but I can't get it consistently.
Is your head spinning?

Not all is perfect however.  When used wide open the Sigma does occasionally show onion-ring bokeh, which can bother some people.  This is because the Sigma has aspherical elements to minimize aberrations.  This is an issue that also affects other lenses such as the Nikon 50 1.4G, Nikon 24-70 and Canon 85L.  In the case of the Sigma, the rings are not very obvious but they can be seen on some highlights when closely examined, moreso than on the Nikon 50 1.4G.  Last test shot with a doll, I promise:
onion rings visible... if you can peel your eyes long enough from the bokeh blobs
The rings don't show up on farther highlights, and they also don't show up when the aperture is narrowed to f/2.0.  In any case, in the sample photos on this post, I did NOT screen out photos with the onion bokeh so you can see how often it shows up and judge for yourself how much of an issue it is in the real world.

B.  Sharpness
The Sigma is sharp at all apertures.  Wide open, it is reasonably sharp:
Glass orb at Bellagio Conservatory

Stopped down to f/2.0 it is very sharp.
Foie gras mushroom burger from Smith & Wollensky
From f/2.8 to f/8 it is crazy sharp (although at these apertures, Canon's 50 1.4 and Nikon 50 1.4 are just as sharp).
f/2.8 - SOOC, no sharpening or clarity adjustment
C.  Focusing
If you have not used a 50 1.4 lens before, be aware that at an aperture of f/1.4 the depth of field can be exceptionally thin when the subject is close.  With the slightest delay between the focus lock and the actual shutter release, the image won't be in focus.  When using this lens wide open for people shots, I usually hold down the shutter button, which means the camera will release the shutter as soon as focus is acquired.  I also get better results using flash and/or a very high shutter speed.  If the subject is moving, I narrow the aperture to f/1.8 or f/2.0.  If the subject is moving around a lot or there is more than one subject, then f/2.8 is probably the widest aperture I would try to use.

With those limits, the Sigma focused with reasonable speed and accuracy.  On my D3 I had to enter a -10 microfocus adjustment on my copy.  On my other cameras (S5, D70, D90) I don't have a microfocus adjustment capability but the lens focuses just fine.

Note: in Canon forums that discuss this lens, a number of people have expressed an issue about the Sigma's autofocus, exhibiting both front- and back-focus on the same copy (making it impossible to correct even with microfocus adjustment).  Many Canonistas who use this lens said that it required exchanging the lens a few times to find a good copy that doesn't have focusing errors.  Alternatively, some Canon shooters have sent their copies to Sigma for recalibration, with good results.


Here are some comparisons between the Sigma and other lenses.

Here are some more shots I took with this lens.  They have what I consider to be minor edits.  To give a more accurate idea of this lens' field of view, I avoided cropping and cropped only to change the frame ratio or to straighten the image.




Although the Sigma is larger and more expensive than Canon's or Nikon's equivalent lens, it has bokeh that is quite possibly the smoothest of any 50mm lens in its class.  Moreover it can produce sharp photos even when used at wide apertures, including wide open.

I would say the Sigma is for someone who...
- Wants a lens for full frame with a focal length range that works with a wide range of subjects (not just portraits) or wants a short telephoto lens for an APS-C camera;
- Wants the smoothest bokeh bar none;
- Doesn't mind occasional onion ring bokeh;
- Wants the sharpest lens for full frame at wide apertures (wider than f/2.0).  Note: For crop-sensor, sharpness is just about the same as that of the Canon 50 1.4 or Nikon 50 1.4G;
- Gives higher priority to center sharpness than edge-to-edge sharpness;
- Doesn't mind the large size.

Note: There are fewer complaints about autofocus in the Nikon mount version of this lens, compared to the Canon version.

Photography on the Net "Sigmalux" thread.  I didn't go through all 500+ pages of the thread, but I like the ones posted by Ximix .

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