Sigma 30/1.4 (for 4/3) Review

I have recently bought a Sigma 30mm f/1.4 lens for my Olympus (4/3 mount) cameras. This lens seems to have been received with a love / hate relationship for most people; those who 'get it' really like it, but there are many who, either through lens defects, improper use, etc do not like the lens. As well, this lens is available in many different mount types; there are few reviews which I could find which are dedicated to the 4/3 mount. To share my opinions of this lens, as well as add a dedicated 4/3 review, I have written this. Feel free to email me if you have any questions or comments.

This review was written with my Olympus E-620 camera in mind, although there should be few differences when used on other bodies.

This lens is made to fill a fairly specific niche on the 4/3 system: a fast, (almost) normal prime. Other than this lens, you have only a few other options: the Leica 25mm/1.4 lens (about twice the price of this one), the Olympus 25mm/2.8 pancake (very nice lens, very portable, but two stops slower), or the Sigma 24mm/1.8 (well received by many, a bit wider, but half a stop slower). Of these, I chose the Sigma 30mm because it was the most cost effective of the group (with the exception of the pancake, which is too slow for my needs), and because it is slightly longer, which can help in portraiture (effective focal length of 60mm, which is just a bit shy of the classical portrait range of 70-90mm or so).

Build Quality and Handling

This is the first thing that you notice when you take it out of the case - this is definitely not a kit lens. The construction feels very good, the focus ring is tight with tactile 'clicks' at the near and far focus limit (even though the ring will turn past the limit, you can feel when it hits). I like this focus ring far better than my other Olympus focus by wire rings, although in practice I doubt that I will use it (as my eyes are not good enough for manual focus anyway). It feels slightly heavier than my 14-54. Overall I would put this in Olympus' HG class at least - it feels very well made.

Something I was delighted to see was how short this lens is. When mounted, it extends almost the same amount as the 14-42mm kit lens. This means (for me) that it will fit very nicely in the Lowepro Rezo TLZ 10 case, which I clip to my belt when I want to bring my camera, but don't need multiple lenses or flashes. This is also nice if you are not one who enjoys sticking huge lenses in friend's or client's faces; while the front of the lens is definitely larger than the kit lenses, it is not intimidating.

On the 4/3 mount, Sigma uses a HSM (HyperSonic Motor) for focusing. They claim benefits to focus speed as well as having a reduced noise level when focusing. I would tend to agree that the motor is quieter than other lenses, especially if it needs to rack through the entire focus range. However, I find that for small adjustments, the lens sounds louder than the 14-54 does for similar small adjustments. That being said, it is still very quiet - the focus confirmation beeps are louder than the lens is!

As for focus speed, things do not appear to be limited by the focus motor at all; instead, the bottleneck seems to be the camera body / AF sensors. Like Olympus' SWD motor, the focus ring does not move when AF is in use, but you always have the option of twisting the focus ring for adjustments. You do not need to switch to MF or AF+MF mode to get the ring to respond. Furthermore, you can even focus manually with the camera off, which is not possible with other lenses.

Focus Accuracy

A common complain about the Sigma 30mm is that many copies seem to back- or front-focus, requiring that you send it in to a Sigma facility for calibration. My copy luckily seems to be free from this issue, so I cannot comment on it. (Note that on newer Olympus bodies, such as the E-620 or E-30, the camera has AF adjustments in software, which allow you to correct issues like this.) As far as normal AF goes, the lens seems to be quite accurate. As with any low DOF lens, you need to be very careful that neither the camera nor the subject moves at all between focus and exposure - even a couple of centimeters will result in a poorly-focused image.

Aperture / Bokeh

This is, of course, the reason why one would buy this lens. While there are many other lenses out there which are either cheaper, sharper, or both, there is nothing in the Olympus lens lineup which can compare with an f/1.4 aperture. The principal reason I am looking for large aperture is for low DOF portraiture (i.e., portraits in which the background is 'blurred away' to give emphasis to the subject). For this, the lens appears to work quite well. Below I have a sample shot of my daughter; you can see that she is in focus, but the background is not.

(Taken with Olympus E-620, Sigma 30mm @ f/1.4, ISO 200, 1/640 second exposure)

(100% crop)

To give a better idea of what the bokeh of this lens looks like, I have included three images of the same subject. All three shots were done in aperture priority on the E-620; the first was at f/1.4, the second at f/2.8, and the third at f/5.6. Note the cluttered background; the hall light and the picture frames on the wall seem to melt away with the lower apertures. The bokeh does not have many hard edges (which can at times create the 'double outline' when shooting things like sticks or other thin, contrasty objects).

Test shot at f/1.4

Test shot at f/2.8

Test shot at f/5.6

One thing to note if you are used to shooting with 35mm cameras or larger DSLRs, is that the depth of field of Olympus (2x crop) cameras is abot 2 stops less than an equivalent full frame. This can be good or bad, depending on your shooting style. Regardless, I feel that it is important to show you about what you can expect when using this lens.

The following shot is of my daughter's homemade toy robot, named Jungle. Jungle is about 2 meters from the camera in this shot, which is approximately the distance you would be when taking a 1/2 or 1/4 length portrait.

Shot at f/1.4, approximately 2 meters from the subject

As you can see, the background is relatively blurred; while you can definitely identiy objects in the background, they tend to blend together more, and lead your eye to the primary subject which is in full focus.

Color Cast

Some people complain that this lens produces pictures with a bit of a yellowish tinge; to test this, I did a comparison between this lens and the Olympus 14-42mm kit lens (at 30mm). I took two shots with a bounced flash and consistent white balance. You can see both shots below:

The top image was taken with the Sigma, the bottom with the Olympus. As you can see, there is a slight yellowish color cast to the Sigma lens; however, unless you have two images side by side, it is almost un-noticeable. Looking at the eyedropper values on the white 'Digital Design' book, near the top of the book, you can see the Sigma lens gives RGB of 210,207,200 while Olympus gives 207,206,202 - there may be 1% more red in the Sigma photo, but personally I don't think it is enough to worry about or even notice. Of course, if you shoot raw you always have the option of adjusting the white balance after the shoot.

Summary

In short, I feel that this lens is a great value if you are looking for one or more of the following:

• Low DOF for portraits
• Fast lens for available light shooting
• A good quality 'normal' prime lens

This lens is not for you if you want any of the following:

• Smallest / lightest lens possible (get the Pancake)
• Zoom