This blog is a user's perspective on the Micro Four Thirds camera system. Read more ...

Lens Buyer's Guide. Panasonic GH4 review.

My lens reviews: Olympus 9mm f/8 fisheye, Lumix G 12-32mm f/3.5-5.6, Leica 25mm f/1.4, Lumix X 12-35mm f/2.8, Lumix X 35-100mm f/2.8, Sigma 30mm f/2.8, Sigma 19mm f/2.8, Lumix X PZ 14-42mm f/3.5-5.6, Lumix X PZ 45-175mm f/4-5.6, Olympus M.Zuiko 45mm f/1.8, Panasonic Lumix G 100-300mm f/4-5.6, Panasonic Leica Lumix DG Macro-Elmarit 45mm f/2.8 1:1 Macro, Panasonic Lumix G 45-200mm f/4-5.6, Panasonic Lumix G 20mm f/1.7 pancake, Panasonic Lumix G 14mm f/2.5 pancake, Panasonic Lumix G HD 14-140mm f/4-5.8, Panasonic Lumix G HD 14-140mm f/3.5-5.6, Panasonic Lumix G 8mm f/3.5 fisheye, Lumix G 7-14mm f/4, Samyang 7.5mm f/3.5 fisheye, Tokina 300mm f/6.3 mirror reflex tele, Lensbaby 5.8mm f/3.5 circular fisheye lens
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Thursday 31 December 2009

Lumix G 20mm f/1.7 pancake

The Panasonic Lumix G 20mm f/1.7 pancake lens was launched in the autumn 2009, and became an instant classic even before it was widely available.

Most people who had a Micro Four Thirds camera by this time probably already owned a kit lens which covers the 20mm focal length, e.g., the Lumix 14-140mm, Lumix 14-45mm, or Olympus 14-42mm. So why add another lens in the same range?

There are several reasons why a lot of people like this lens. The focal length corresponds to 40mm on an old style 35mm film based camera, which can be considered as a slightly wide normal focal length. While there is nothing magical about this "normal" focal length, it is considered to give images that look normal to a human observer, in terms of perspective. It sits between wide angle and tele lenses, and while different photographers have different tastes, it remains a useful focal length for a lot of situations.

Tuesday 29 December 2009

GH1 autofocus speed comparison

I have made some tests of the autofocus speed of the Panasonic Lumix GH1 camera with various lenses. The camera focused from infinity (the default position of the lens when powering down) to near the minimum focus distance, and I used a LEGO figure as the subject.

The test was done in indoor lightning, about EV6. The focus time is measured as the time from my finger presses the shutter button until the green focus confirmation light comes up in the display. The picture is taken immediately after focus is achieved, within one tenth of a second.

You will hear the shutter operating twice, since the camera was in multi exposure mode. I did confirm that all the images were indeed in focus, as is expected with a contrast detection autofocus system (CDAF).


Before going into the details, here is a quick summary

Lumix G 20mm1.23 seconds
Lumix G HD 14-140 @ 18mm0.53 seconds
Lumix G HD 14-140 @ 50mm0.40 seconds
Lumix G HD 14-140 @ 140mm1.63 seconds
Lumix G 45-200 @ 45mm0.33 seconds
Lumix G 45-200 @ 100mm0.36 seconds
Lumix G 45-200 @ 200mm0.87 seconds
Olympus 4/3 9-18 @ 9mm2.90 seconds
Olympus 4/3 9-18 @ 18mm1.50 seconds

What is a bit surprising here, is that the 45-200mm lens is quicker than the HD 14-140mm. The latter is marketed as a very quick focusing lens, optimized for video, hence the HD designation. However, the 45-200mm lens has an advantage, since it's close focusing distance is 100cm, twice that of the HD 14-140mm. So when focusing from infinity to the minimum focusing distance, the HD 14-140mm has a longer way to travel.

Lens: Panasonic Lumix G 20mm f/1.7

Autofocus from infinity to 23cm: 1.23 seconds.
The minimum focus distance of the lens is 20cm.

Lens: Panasonic Lumix G 14-140mm HD f/4-5.8

Focal length 18mm (36mm in 35mm camera equivalent), f/4.3:

Autofocus from infinity to 53cm: 0.53 seconds.
The minimum focus distance of the lens is 50cm.

Focal length 50mm (100mm in 35mm camera equivalent), f/5.6:

Autofocus from infinity to 53cm: 0.40 seconds.
The minimum focus distance of the lens is 50cm.

Focal length 140mm (280mm in 35mm camera equivalent), f/5.8:

Autofocus from infinity to 53cm: 1.63 seconds.
The minimum focus distance of the lens is 50cm.

The outcome for f=140mm deserves some more comments. As you can see from the video, the focus is hunting a bit before settling. I tried to redo this experiment several times, and found that the outcomes were very consistent. My speculation is that I have been operating close to the minimum focus distance, and that perhaps this distance is slightly longer in the tele setting. Indeed, moving the subject a bit further away from the camera gave focus speed consistent with 18mm and 50mm focal lengths.

I have also tested this with the firmware versions v1.2 and v1.3, and concluded that the issue has been fixed. The lightning was comparable, and even though I moved the figure around close to the minimum focus distance, I was not able to reproduce the focus hunting. Rather, the focus speed has improved a lot with the newer firmware, it seems.

Lens: Panasonic Lumix G 45-200mm f/4-5.6

Focal length 45mm (90mm in 35mm camera equivalent), f/4.0:

Autofocus from infinity to 1m: 0.33 seconds.

Focal length 100mm (200mm in 35mm camera equivalent), f/4.6:

Autofocus from infinity to 1m: 0.36 seconds.

Focal length 200mm (400mm in 35mm camera equivalent), f/5.6:

Autofocus from infinity to 1m: 0.87 seconds.

Lens: Olympus Zuiko Digital ED 9-18mm f/4-5.6

Note that this is not a Micro Four Thirds standard lens, but rather a lens for the Four Thirds DSLR system. To mount this lens on a Micro Four Thirds camera, you will need and adapter. I used with the adapter Panasonic DMW-MA1, but the Olympus MMF-1 adapter is functionally the same, and would have done the same job.

Not all Four Thirds lenses can autofocus on Panasonic Micro Four Thirds bodies, like the GH1. Here is a list.

Focal length 9mm (18mm in 35mm camera equivalent), f/4:

Autofocus from infinity to 25cm: 2.90 seconds.
The minimum focus distance of the lens is 25cm.

Focal length 18mm (36mm in 35mm camera equivalent), f/5.6:

Autofocus from infinity to 25cm: 1.50 seconds.
The minimum focus distance of the lens is 25cm.


The autofocus speed of the Lumix G HD 14-140mm lens is the fastest in this comparison, which is as expected. The unexpected result in this context was the significantly slower autofocus speed at full tele, 140mm, however there is reason to believe that this was related to operating close to the minimum focus distance, as discussed above.

Just as with the superzoom above, the Lumix G 45-200mm features very impressive autofocus speed. The exception is at full tele, however, the speed at 200mm is still very good. The autofocus is virtually inaudible.

The Lumix G 20mm lens does indeed focus slower than the HD lens, and also somewhat more audibly.

Using autofocus with the Olympus 9-18mm Four Thirds lens is possible, but pretty slow. Especially at the wide angle setting. Focusing with this lens is also quite noisy. Taking pictures of moving subjects, e.g., children, with this lens could pose some difficulty with autofocus. In this case, it could be wise to prefocus, and set the camera to manual focus (MF) while composing the image. That way, you can take the picture nearly instantly when pressing the shutter, rather than having to wait some seconds for the autofocus to settle.

Lumix G 20mm1.23 seconds
Lumix G HD 14-140 @ 18mm0.53 seconds
Lumix G HD 14-140 @ 50mm0.40 seconds
Lumix G HD 14-140 @ 140mm1.63 seconds
Lumix G 45-200 @ 45mm0.33 seconds
Lumix G 45-200 @ 100mm0.36 seconds
Lumix G 45-200 @ 200mm0.87 seconds
Olympus 4/3 9-18 @ 9mm2.90 seconds
Olympus 4/3 9-18 @ 18mm1.50 seconds

Mostly, you will not focus down to near the minimum focus limit of the lens, and so autofocus will usually be faster than these examples. The Olympus 9-18mm lens is a bit of an exception to this, however, as even focusing on a distant subject takes virtually as long time as focusing close.

Rumors say that future Panasonic models, like Lumix G2 and Lumix G10, will focus faster with Four Thirds lenses on an adapter.

Friday 25 December 2009

Lumix G HD 14-140mm f/4-5.8 zoom lens

It is only natural that the Panasonic Lumix 14-140mm zoom lens is associated with the Panasonic Lumix GH1 camera: They were both only available as a kit for the first months following the launch in spring 2009. It was only after some time that the lens could be bought alone. From January 2010, the GH1 can be purchased as body only in the UK.

The lens has a 10x zoom ratio, and falls into the superzoom category. As is common for lenses of this type, it has a wide angle 28mm starting point (in 35mm camera equivalent terms), and goes all the way up to 280mm, which can be considered as a long telephoto lens.

This long zoom range comes at the cost of an aperture range which is not as impressive: f/4 at the wide angle, and f/5.8 at the long end.

One of the benefits of the Micro Four Thirds system is the compact size, and this benefit seems to be negated by the size of this lens. Even attaching it to the Panasonic GF1, the smallest M43 camera at the time of writing, gives a rather large and bulky package.

Since writing this, the lens has been superseded by the Lumix G HD 14-140mm f/3.5-5.6, which is smaller, lighter, and better in almost any way. I would certainly recommend that you consider the newer lens over the old one.

Aperture range

When looking at the aperture range of zoom lenses, it is common to observe the apertures of the end points. The aperture range, however, is far from linear. It increases faster than you might expect. The diagram below illustrates the aperture at various focal lengths (at 35mm camera equivalent) for the Lumix 14-140mm (blue) and the Nikon 18-200mm (red). As you can see, the Lumix lens has the smallest aperture range of the two, which we already knew, but in addition, the aperture closes down faster as the focal range increases, compared with the Nikon lens.

The 14-140mm lens has been criticized of being overly expensive, compared with similar lenses on the market. For example, the AF-S Zoom-Nikkor ED 18-200mm f/3.5-5.6G IF DX VR, with an 11% longer zoom range, half a stop larger aperture in the wide end, and is less expensive. Canon has also got a lens with the same specifications as the Nikon, and at an even more attractive price point.

Some answers to these comments have been that the 14-140mm has some unique features not found on other lenses: It is optimized for video recording, and features low noise fast autofocus, and an aperture that can change almost steplessly (at 1/6 stop intervals), and almost inaudibly. The aperture is also marketed as being very precise. Another advantage compared with the Nikon and Canon lenses is that it is more compact, at about 15% shorter at the wide angle setting.


I have compared the bokeh of the lens with the Lumix 20mm f/1.7 pancake lens, with the 45mm f/2.8 macro and the 45-200mm f/4-5.6 zoom lenses and the Lumix 14mm f/2.5 lens. It is fair to say that the bokeh of the 14-140mm superzoom lens is not the best. It is a bit "dirty" and features some ringing. However, with the limited maximum aperture, you're not likely to see much out of focus rendering anyway, so this is not a problem. The 14-140mm zoom lens is also more prone to flare, probably due to the complicated construction featuring 17 lens elements in 13 groups.


When using this lens on the Lumix GH1 camera in auto mode, the camera will almost always choose the largest aperture. The exception is outdoors photography in generous sunshine at wide angle. It is good then, that the lens is pretty sharp from the fastest aperture over most of the zoom range. There is little need to stop down, unless you need a very sharp image.

The images are somewhat soft at full aperture in the telephoto focal lengths, though. However, there is seldom room for stopping down the aperture further when photographing at full tele extension, as the shutter speeds tend to be on the slower side already. If you're using a tripod, and are photographing non-moving subjects, you could benefit from using a somewhat smaller aperture.

Here is a sharpness comparison with four other lenses at 140mm. This lens does not perform the best here, and, generally, the newer Lumix G HD 14-140mm f/3.5-5.6 is better.

Here is an example image taken at full tele, 140mm. I used f/5.8, ISO 320, 1/200 second handheld. The picture features the author Erlend Loe.

Here is an example video recording, filmed handheld, at f=108mm (216mm film equivalent), 1/100 second shutter speed, f/5.8, ISO 400.

Image Stabilization

The goal of Image Stabilization (IS) is to be able to take images handheld (or on monopod) at a slower shutter speed than otherwise possible. If the image is too dark, the photographer has the options of increasing the ISO sensitivity, using a larger aperture, or using a slower shutter speed. In some cases, it might be impossible, or undesirable, to increase the ISO sensitivity, or to use a larger aperture. If using a slower shutter speed would normally be impossible due to camera shake, IS might be able to save the picture, stabilizing the image as recorded by the sensor.

At higher sensitivity, the image quality is usually worse, and there are limits to how large the aperture can be on a lens. Large aperture lenses are usually bulky and expensive, and even they have a limited aperture. A large aperture can also be more tricky to focus with, since it will give a narrow depth of field, and the image is usually not the sharpest at the largest aperture. These are some examples of reasons why the photographer might prefer to use a slower shutter speed.

Note that while IS can reduce the effect of camera shake on the sharpness of the image, it does not stabilize whatever you are photographing. If you are photographing moving subjects, you will still need a shutter speed fast enough to freeze the movement, if that is what you want.

The concept of Image Stabilization on consumer cameras was first introduced in the nineties. At that time, most cameras were film based, and the only option for a stabilization technique was through the lens. Later, digital cameras have become the most used, and with this invention another technique for stabilizing the image has arisen: Through shifting the sensor. This could not be done in any efficient way with film based cameras, since the film to be exposed is part of a strip which goes through two spools.

Is is no surprise that the camera systems that have been dominating since before the conversion to digital have retained lens based IS, also called Optical Image Stabilization (OIS). Nikon and Canon both had a number of OIS lenses available before digital photography became common. On the other hand, some systems that have been reinvented for digital have employed sensor based IS, for example Olympus (with the Four Thirds System), Konica-Minolta (later Sony) and Pentax. Some systems, predominantly larger format professional systems, offer no image stabilization at all, e.g., Hasselblad and Leica S2. These systems are mostly intended to be used on tripods, hence IS is hardly needed.

Olympus and Panasonic have taken different approaches to IS. Panasonic have chosen to employ image stabilization through the lens (OIS), denoted with their trademarks "Mega O.I.S." or "Power O.I.S.". Olympus, on the other hand, stabilize the image through sensor shift inside the camera body.

There are advantages and disadvantages with both approaches. The camera body sensor shift technique means that any lens attached can be stabilized. The advantages are obvious: You don't need to pay a premium for OIS lenses, and you can use legacy lenses stabilized. The latter point is very interesting, since Micro Four Thirds cameras, with the short register distance, can use a large number of legacy lenses through adapters.

Lens based OIS, on the other hand, has an advantage with long lenses. The longer the lens, the longer the sensor needs to travel sideways to stabilize the image, in the case of in body OIS. For obvious reasons, there are limits to how far the sensor can travel. With lens based stabilization, lens groups inside the lens shift the path of the light, so that the image is always focused on the sensor. This has an added benefit that the image circle of the lens is used more efficiently.

Even if Olympus and Panasonic have chosen different approaches to IS, you can still use Olympus lenses on Panasonic cameras, and the other way around. But you should not use both image stabilization methods at the same time, if you have a camera/lens combination in which this is possible. This will lead to an over-compensation for camera shake, and will give less sharp images.

Personally, I like the idea of sensor shift IS better than lens based OIS. I think that in camera sensor based IS enables you to use a wide variety of lenses with stabilization, including older legacy lenses. Another benefit is that there is no need for additional stabilizing lens groups in the optical path in the lens. This would be more complicated and costly to produce. The more lens elements the light need to pass through, the more potential for degrading the image quality.

In practice, though, we can see now that the Panasonic Lumix G 14-45mm Mega O.I.S. lens is not significantly more expensive than the Olympus M.Zuiko 14-42mm, even though the Panasonic lens features a stabilizer. Also, the Panasonic lens has generally been found to give better image quality, despite the extra lens elements dedicated to stabilization.

Even though my preference is towards camera based stabilization, I still chose to buy the Panasonic Lumix GH1 and GH2, as I felt that it had more features that I liked. For example, I like the high resolution electronic viewfinder, the tiltable LCD display, the better grip, and the more usable autofocus speed. At the time of buying there was the Olympus E-P1 available, with sensor based IS, however, I felt that it could not compete with the GH1 in the areas mentioned above.


This blog is a user's perspective on the Micro Four Thirds camera system. While I intend to keep the contents fact based, there are many areas where no objective truth is available, and hence there is room for different opinions and discussions. I would like to encourage you to contribute with your own experiences or opinions to this blog through the comments fields.

The Micro Four Thirds system was announced jointly by Olympus and Panasonic on August 5th, 2008. The first camera model was launched in November the same year.

Since this time, a number of cameras and lenses have become available for this system. While you can use Micro Four Thirds Olympus lenses with Panasonic cameras and vice versa, they have effectively made two different subsystems due to a different approach to optical image stabilization (OIS): Olympus cameras have images stabilization based on sensor shift inside the body, and no lens based OIS. Panasonic, on the other hand, do not use sensor shift image stabilization at all, but rather employ OIS through some lenses, by having some moving lens groups that are intended to cancel the negative effect of camera shake. These Panasonic lenses are denoted with the trademark "Mega O.I.S.".