Wednesday, 6 January 2010

Four Thirds system

The Four Thirds systems is a DSLR camera system originally developed by Olympus and Kodak. The first Olympus camera was announced in 2003 (the professional grade Olympus E-1), along with four lenses.

While the major players in the DSLR camera market based their digital cameras on their existing film camera mounts and lenses, Olympus did not have a significant user base at this time, and found it better to design a new system from ground up, based on the requirements of digital photography.

Aspect ratio and sensor size

The name "Four Thirds" cleverly refers to two things at the same time:

  • The image aspect ratio. While the aspect ratio of 35mm film cameras is 3:2, the Four Thirds system has a more square aspect ratio of 4:3. There are many reasons for this, e.g., a typical print size is 8:10, with a more similar aspect ratio to 4:3. And professional medium formats are typically closer to square aspects, like 4.5x6, 6x6 and 6x7. However, since the introduction of Four Thirds, formats that are even wider than 3:2 have become popular. TV sets are now typically 16:9. I still think that 4:3 makes sense for photography. A more square format uses the image circle more efficiently, which is an advantage, assuming, of course, that you're not going to crop it down to a more rectangular format.
  • The size of the sensor. The sensor has the same size as the imageing area of a 4/3'' diameter legacy cathode ray tube for video cameras. The actual size of the sensor is still significantly smaller than 4/3'', with the diagonal of the imaging area usually being 21.6 mm.
The Four Thirds sensor size is about 30-40% smaller than the APS-C sensors commonly used in other DSLR systems. This has various consequences:

  • In theory, a smaller sensor usually means worse high ISO capabilities, and worse dynamic range characteristics, given the same number of pixels, and the same sensor technology.
  • The depth of field is larger with a smaller sensor. This means that given the same distance, field of view and aperture, more will be in focus with a smaller sensor. This is both an advantage and a disadvantage. In landscape photography, you will most often want sharpness across the image, and a wide depth of field. On the other hand, in portrait photography, it is often desireable to have a narrow depth of field, to achieve isolation of the subject, and blurring of the background.
  • A smaller sensor will limit the useful range of apertures more, due to diffraction, again assuming the same number of pixels. Diffraction will make the image blurry at pixel level when using small apertures. This is not due to bad design, but rather the result of the laws of nature.
  • Designing lenses and cameras around smaller sensors is in some ways easier: They can be made more compact.
  • A small sensor gives a higher crop factor. The crop factor of the Four Thirds sensor is roughly 2x, meaning that the focal length in mm for a Four Thirds lens must be multiplied with 2 to get the equivalent focal length on a traditional 35mm camera. Hence, a 14mm lens on Four Thirds is a wide angle lens, corresponding to 28mm on a traditional film camera. Some suggest that with this background, systems with a high crop factor are good for people who need long lenses, e.g., for wildlife photography. However, there are lenses to suit virtually all needs in the Four Thirds system.

Lens design

Another important aspect of the Four Thirds mount is the register distance, also called the flange focal distance. The register distance is the distance between the lens mount and the sensor plane. With the sensor size being smaller than for other DSLR systems, the Four Thirds system also has a smaller register distance. This aspect of the camera systems makes designing lenses, especially wide angle lenses, easier.

Olympus lenses are commonly more telecentric than lenses from other systems, especially lenses that were originally designed for film. The telecentric property of a lens means that the light rays coming from the lens hit the sensor at a more normal angle across the field, especially in the corners. This is important for digital photography, since the sensors are sensitive to the angle of the light rays: If the light rays are hitting the sensor at a narrower angle in the corners, a significant portion of the light will be lost in the sensor pixel bins, giving heavy vignetting. More telecentric lenses generally give less vignetting in the corners. However, designing telecentric lenses is more complicated, and some of the size advantage of the smaller sensor is lost with this property of the lenses.


The original cameras in the Four Thirds system were not so compact, and, while they were innovative, they were also somewhat strange looking. Later, Olympus launched smaller cameras, with the E-4xx series being the smallest DSLRs on the market at the time of availability. The cameras have also been more traditional looking after the first two-three years. After some years of maturing, the Olympus DSLRs are not very different from the competitors, beyond being somewhat smaller.

Panasonic and Leica have also issued cameras in the Four Thirds system, however with major components Olympus sourced. The Leica branded cameras have largely been similar to Panasonic models, with smaller changes to the design and software. Since this time, both Panasonic and Leica appear to have withdrawn from the Four Thirds system, with Panasonic focusing more on the newer and more compact Micro Four Thirds system, and Leica designing their own high end cameras, e.g., the Leica X1. Leica still appears to have some involvement in the design of lenses for the Micro Four Thirds system, with the Leica branded 45mm f/2.8 macro lens launched in the autumn 2009.

A new standard was announced in 2008, the Micro Four Thirds. This shares the sensor size with Four Thirds, however, leaving no room for a mirror assembly. Panasonic G1, the first camera for this standard, was launched in the autumn 2008. The new system has been very successful in Japan, and Panasonic cameras and lenses have been scarce in Europe and especially the US in 2009, suggesting a high demand.

According to the statistics quoted above, the Olympus E-P1 Micro Four Thirds camera was the most selling Olympus camera model in Japan 2009. This has prompted some concern that Olympus might discontinue the regular Four Thirds line, and focus exclusively on Micro Four Thirds. I think the chances for this are slim at the moment, since Olympus has a large and good back catalogue of Four Thirds lenses. While the E-P1 camera has sold a lot, I am sure that they have sold a lot of Four Thirds lenses as well, not recorded by the statistics.

Saturday, 2 January 2010

Manual focus with Lumix GH1

Here is a video that illustrates how manual focusing is done with the Panasonic Lumix GH1 camera. The Olympus 50mm f/2 macro lens is attached to the camera through the Panasonic DMW-MA1 adapter. The adapter is needed since the lens is a Four Thirds standard lens. No autofocus is possible with this combination.


When powering on the camera, it prompts you to switch to manual focus mode. This is not needed. You can leave the camera in autofocus mode, however, no autofocus is possible, of course.

Turning the focus dial will enable the zoomed view. What you see now is a 5x magnification of the centre of the image.

Tapping the shutter release gently brings up the normal full view again.

In the magnified focus assist view, you can use the front dial to switch between 5x and 10x magnification. You can also use the arrow buttons to move the magnified area around, in case you do not want to focus on the centre of the frame.

When you power down the camera, the lens will retract to infinity focus.

It would have been good to have a dedicated button to alter between the magnified focus assist view, and the normal view. While you can bring up the normal view by tapping the shutter release, turning the focus dial, which you may not always want to do. You could also use the focus area button on the rear, and then press OK, which brings up the zoomed view.

Olympus Zuiko Digital 50mm 1:2 Macro

This is an unusual lens. Not only is it a macro lens capable of photographing subjects as small as 2x the sensor size (hence the 1:2 designation), but it is also a fast short tele suitable for portraits, with a maximum aperture of f/2. The focal length is 50mm, however, with the 2x crop factor associated with Four Thirds, it will have the same field of view as a 100mm lens on a traditional 35mm camera.

Since this is a Four Thirds standard lens, it cannot be used on a Micro Four Thirds camera without an adapter. It is shown here with the Panasonic DMW-MA1 adapter attached. The Olympus MMF1/MMF2 adapter would have done the same job, as it is functionally the same, albeit usually somewhat more expensive at retail.


Unfortunately, you cannot use autofocus with this lens together with the first series of Panasonic Micro Four Thirds camera bodies (G1, GH1, GF1). The Olympus cameras, and newer Panasonic cameras, on the other hand, can do autofocus with this lens, albeit operating at a slow speed. Here is a demonstration of the autofocus using Panasonic GH2, which takes five seconds to focus down to 45 cm distance:

Here is a demonstration of manual focusing with this lens on a Panasonic Lumix GH1.

Some Four Thirds lenses can autofocus on Panasonic Micro Four Thirds bodies.

The closest focus distance is 0.23 m. Be aware, though, that the focus distance is measured from the focal plane (the sensor), and so the distance between the front lens and the subject at closest focus is about 0.1 m.

The lens is also special in that it is one of the few Four Thirds lenses that feature a focus scale.


Compared with the Lumix G 20mm pancake lens, the Olympus 50mm macro, including adapter and hood, is enormous. However, it is of course more natural to compare it with other 100mm equivalent macro lenses, in which case it is remarkably compact.

It is somewhat smaller than the Lumix G HD 14-140mm kit lens.

Macro lens

Most macro lenses have a maximum aperture of f/2.8 or slower, e.g., Sigma 105mm f/2.8 and Tamron 90mm f/2.8, both in the same focal length range. Hence, a f/2 macro lens is unusual, and some might say this speed is not needed. You would rarely photograph small subjects with such a large aperture, since the depth of field (DOF) becomes very narrow. Unless the subject is more or less flat, only a small part of it will be in focus at f/2. Stopping down to at least f/5.6 may be needed to have a sensible depth of field at close focus.

Here is a series of photos that illustrate the depth of field at 25cm distance, and various aperture sizes. The focus is set to the centre face. The distance in the axis of the lens between the three heads is one LEGO unit, or 8mm, if your not familiar with this measure. You must stop down to f/16 to get a depth of field that covers this distance.

At such a small aperture as f/16, you are going to see some lack of sharpness at the pixel level due to diffraction. You may still choose a small aperture like this, however, if you need a wide depth of field, and can live with some dullness at pixel level. For web use, for example, where you will normally scale down the image, this should not be any problem.

In macro photography, it is uncommon to use autofocus, since you will need to fine tune the focus anyway to get the desired effect. So the lack of autofocus on Panasonic Micro Four Thirds cameras is not a problem for macro photography.


I've made a study of the bokeh of the lens. My conclusion is that the bokeh is very pleasing, although the out of focus highlights have a somewhat hard edge. But in general, you're unlikely to be dissatisfied with the bokeh using this lens.

Portrait lens

When taking headshots, it is common to keep some distance to the subject. This is done to avoid perspective distortion. Taking a picture of someones face from a short distance will usually give unwanted distortions, e.g., showing an unnaturally large nose or a large chin. Traditionally, an 85mm lens has been used on a 35mm camera to be able to fill the head and shoulders of a person in a picture frame, and still keep enough distance to the person to avoid perspective distortion. The Olympus 50mm macro lens corresponds to 100mm focal length on a 35mm camera, and so it is useful for portraits.

A traditional portrait lens will be around 85mm f/1.4. The Olympus 50mm macro has one stop slower aperture at f/2, but it is still large enough to isolate the background when taking portraits.

In studio photography, the lack of autofocus is not likely to be a problem. If you're photographing people in a more dynamic environment, you may see the need for autofocus.

Other uses

You could also use this lens for concert photography, given that you're placed not too close to the stage, and the people on the stage are not moving around too much. If you've got something to rest the lens against, you may be able to use longer shutter speeds.


This lens is generally considered to be among the best in the Olympus Four Thirds lineup. It is remarkably sharp from f/2, but close it down a bit for even better sharpness. At f/5.6 it is probably around the sharpest.

Chromatic aberrations

I have made a study of the chromatic aberration (CA) artifacts of this lens, and some other prime lenses. It shows that there are quite some red/green fringing artifacts even in the centre of the image. You will note this if you photograph high contrast images.

Image stabilization

Using this lens with a Panasonic Micro Four Thirds camera, there is no image stabilization available at all. You'll normally want to use a fairly short shutter speed, e.g., 1/60 second or faster, to avoid camera shake affecting the image when handholding the camera.

Olympus Micro Four Thirds cameras have image stabilization built into the bodies, which will work with this lens.

It is perfectly possible to use this lens when recording videos. However, you can only focus manually on Panasonic cameras. With the lack of image stabilization, and a pretty long focal length, it is more or less impossible to handhold the camera stably while recording movies. Using the electronic viewfinder and pressing the camera against your face may help you to stabilize it a bit. But using a tripod is preferred when filming with this lens.


The lens comes with a bayonet hood, to protect against stray light. I found the hood to be a tad bit long, making it difficult to fit the camera with lens and hood inside my small camera bag, so I chose to use a 52mm screw-in hood from B+W. The hood also protects the front lens element from objects touching it accidentally.

Example picture

Here is an example picture of a broken Leatherman tool taken at maximum magnification (closest focus distance), f/10, 1/5 s, ISO 100.

Other macro options

It is also possible to achieve macro close up photos by using macro extension rings.

Another, more expensive, option is to use the Panasonic Leica Lumix 45mm f/2.8 1:1 Macro lens, which is a native Micro Four Thirds lens.

Friday, 1 January 2010

Market shares in Japan

Update: I have compiled newer statistics based on 2010, which supersede this material.

The Japan market shares are usually published every year. The figures comprise system camera units sold in Japan, mostly DSLRs, but the new Micro Four Thirds cameras are included as well. Only the 20 camera models with the largest sold volumes are included in the statistics. Other camera models, with less sales than these, are in the "Others" category.

I have concatenated the 2009 statistics (as at Dec 23rd) with the 2008 statistics, to be able to see the development better:

To make it easier to digest, I have split the figures into camera systems:

Before starting to comment on these figures, it is useful to note that the "Others" category is larger in 2009. This means that the volume of the smallest camera models has increased. We don't know how large the volume of various camera systems are here, but it is reasonable to guess that we would find some more Olympus, Sony and Nikon models in the 2009 "Others" category.

Canon has held their market share remarkably well. It is also worth noting that the full frame camera Canon 5D Mark II has a fairly high market share at 2.1%.

Nikon appears to have lost significant market shares, which must be very bad news for them. On the other hand, it is reasonable to guess that they have somewhat more volume in the "Others" category in 2009, with, e.g., the Nikon D300 and Nikon D700.

Sony must also be very disappointed, with less than 50% of the 2008 market shares. Again, though, they probably have more camera models in "Others" in 2009.

Pentax have succeeded with their strategy of launching entry models packed with features.

Olympus have only got one Four Thirds model in the 2009 list of the twenty most sold camera models, compared with three in the 2008 list. On the other hand, the E-P1 camera has been very popular, and made up for the lost Four Thirds units.

The Micro Four Thirds system has a total of 11.5% of the new sales in Japan in 2009, which I think is very remarkable. After all, the system was launched in 2008, and only two small players in the system camera market are behind it.


For the fiscal year 2007 (actually only January through November), I could only find DSLR sales in summary form: Nikon 43.3%, Canon 39.9% and Pentax 6.3%, with the other producers being smaller.


This table contains DSLR market shares in Japan by December 2006, for the largest ten camera models. I find it hard to believe that the D40 has already captured 15.5% of the total market in December 2006, since it was introduced the same month. However, this table might have been adjusted for the introduction time of each model.

Summary 2006-2009

All of this information can be summarized into one table, but please be aware that the numbers are not entirely comparable from year to year. Still, there is a trend to be seen.

2005-2009 from another source

BCNranking has published statistics for the three most sold brands within interchangeable lens cameras, meaning DSLRs and hybrid systems like Micro Four Thirds. This table shows the same trend as the other material:

We can see that while Canon has had a stable marked share the most recent years, they have actually had a significant decline when looking back five years. Also, Nikon had a good period around 2007, probably due to the launch of D40, but has not been able to sustain the growth.

Panasonic is the big surprise in 2009, with a third place due to the Micro Four Thirds bodies, probably mostly the G1, having been on the market for the whole 2009.