Comparison @ 60mm

These are two of the most highly regarded lenses in the Micro Four Thirds lineup: The Sigma 60mm f/2.8 DN (left) and Lumix X 35-100mm f/2.8 (right):

The Sigma 60mm f/2.8 DN is a quite recent lens in their "Art line". Corresponding to a field of view of 120mm on a traditional film camera, it is a fairly long lens, slightly longer than the typical portrait lens. People often use it to take portraits, and for images of people from about 2-4 meter distance.



The maximum aperture of f/2.8 does not sound very impressive, but on a fairly long lens, it means that you can get quite good selective focus anyway. The lens is known for good sharpness and nice bokeh.

The Lumix X 35-100mm f/2.8 is Panasonic's take on the traditional pro tele zoom lens. It is one of the most expensive lenses in the Micro Four Thirds lineup, and is generally considered to be very good. As you zoom, the lens does not extend, which is very convenient and makes the lens feel solid.

Lens	Sigma 60mm f/2.8 DN	Lumix X 35-100mm f/2.8
Lens elements/groups	8/6	18/13
Aperture diaphragm blades	7	7
Minimum focus	0.5m	0.85m
Diameter	61mm	67mm
Length	56mm	100mm
Filter thread	46mm	58mm
Weight	190g	360g
Hood included	Yes, but wide and pretty useless	Yes, well designed
Optical image stabilisation	No	Yes
Price	$240	$1000

The test

With both lenses being very well regarded, it is interesting to do a comparison of them. Here is a photo of some trees quite far away:

Sigma 60mm @ f/2.8	Lumix 35-100mm @ f/2.8

To better compare the image quality, here are some 100% crops from the centre of the images (click for larger images):

And from the lower right corner:

Here is another comparison, also taken from a fair distance:

Sigma 60mm @ f/2.8	Lumix 35-100mm @ f/2.8

It is easier to see the differences by enlarging the images from the centre:

And from the left frame:

Image quality

Both lenses are performing very well here, and it is difficult to compare them. In the centre, they are pretty much flawless already wide open at f/2.8. Perhaps the Sigma 60mm lens looks a bit better at f/2.8, but the difference is very minor.

In the corners, the Sigma 60mm lens appears to be somewhat duller, and does not sharpen up even when stopping down to f/5.6. The Lumix 35-100mm, on the other hand, is quite impressively sharp already from f/2.8, and becomes even better when stopping down to f/5.6.

Still, it is fair to say that both lenses do very well, and would satisfy most conceivable needs in terms of sharpness.

Bokeh

These are lenses one would typically use wide open for the selective focus look. Hence, it is important that they are sharp wide open, which I tested in the previous section.

It is also important that the out of focus rendering (bokeh) is pleasant. To test this, I took these photos. I focused on the power outlet to the right. The focus distance is about two meters, a suitable distance for a people portrait with these lenses. Here are the full images:

Sigma 60mm @ f/2.8	Lumix 35-100mm @ f/2.8

And some closeups on the out of focus rendering:

Both lenses do quite well here in terms of bokeh. The Sigma 60mm f/2.8 DN probably has the upper hand here, though, as the out of focus highlights are more round. But the differences are fairly small. Both lenses do very well.

Alternative lenses

If you are looking for long, fast lenses, there are not that many to choose from. Olympus has a 40-150mm f/2.8 pro zoom lens coming, but it will be quite large, and very expensive.

In the mean time, you could go for the Olympus 75mm f/1.8, which is generally regarded as a very good lens: Sharp, and with a nice bokeh. If you are prepared to pay the fairly expensive price, you can hardly go wrong with this lens.

A lower cost alternative is the Olympus 45mm f/1.8, which is a reasonably priced and well performing portrait lens.

Olympus also have a macro lens specified at 60mm f/2.8. It is generally well regarded, and could be a good choice if you also have an interest in macro imaging.

Conclusion

Both these lenses are true to their reputation: They are very good indeed.

Which you choose depend on your budget, and your shooting style. The Sigma 60mm f/2.8 DN, lacking a zoom, is more useful for those who like to take more time photographing, being more open to move around and plan for the best composition.

The Lumix X 35-100mm f/2.8 is more flexible, with the 3x zoom range. The built in optical image stabilization also adds value for those who are interested in video recording.

For the a very good lens at a reasonable price, go for the Sigma lens. For a versatile and stellar performance lens, go for the Lumix lens.

The camera

I took all these images using the Lumix GM1, which is a very powerful camera in a compact and stealthy package. The camera is mounted to the Lumix X 35-100mm f/2.8 here. Can you spot the camera?

I had the camera mounted to a tripod, and took all the images at ISO 200, with 2s shutter delay to avoid camera shake.