Tuesday, 29 January 2013

New Panasonic kit zoom lens

Today, a new Panasonic Lumix kit zoom lens was announced. This doesn't look like a very interesting lens for seasoned Micro Four Thirds users, as it has the rather boring specifications 14-42mm f/3.5-5.6. Panasonic has already released three lenses with similar specifications, so why make one more?

Lumix G 14-42mm f/3.5-5.6 released in 2013

Here are two of the previous lenses:

Lumix LensG 14-45mmG 14-42mmX PZ 14-42mmG 14-42 II
Year released2008201020112013
Filter thread52mm52mm37mm46mm
Front lens diameter*45mm30mm21mm25mm

*) The front lens diameter is not stated in the lens specifications, but is based on my own measurements, supplemented with inspections of product photos.

I'm guessing that the new lens will replace the 2010 Lumix G 14-42mm f/3.5-5.6 kit zoom lens. It makes no sense to replace the Lumix X PZ 14-42mm f/3.5-5.6 pancake lens, since Panasonic needs this one to compete with a similar lens from the Sony NEX system, the Sony 16-50mm f/3.5-5.6 pancake zoom lens.

When looking at this table, it is quite clear why Panasonic is replacing the 2010 zoom lens. The new lens is smaller, and lighter. It probably uses a plastic lens mount, which I see as no problem for such a small lens.

The compactness is an important selling argument for Micro Four Thirds lenses. With smaller and smaller competitors, Panasonic must step up and make even smaller stuff, to stay competitive. The old kit zoom lens was not as compact, and hence, not attractive enough for the market.

The new lens appears to be the type which is the most compact at the centre of the zoom range, unlike the older Lumix G 14-42mm, but like APS-C tele zoom lenses.

Another observation is that the front lens element is smaller than that of the 2010 14-42mm lens, but larger than that of the pancake powerzoom 14-42mm lens. The pancake zoom lens achieves the small front lens element by sacrificing aperture speed in the middle of the zoom focal range. Here is a diagram illustrating the aperture as a function of the focal length for the two lenses:

The Lumix X PZ 45-175mm also achieves a smaller front lens element in the same way. Read about it here. With this in mind, I'm guessing the new lens will have an aperture range somewhere between the two lenses above. One could say that this is a form of cheating: Panasonic achieves a more compact lens by lessening the specifications in a way which is not visible in the lens name: The aperture end points are still f/3.5-5.6.

As for the finish of the new lens, it has the new glossy appearance. I'm not too happy with this, as I prefer lenses to be matte and non-obtrusive. But it appears that glossy is what the market demands at this time.

Other lens news

Incidentally, other lens news also fall into the same category: Remakes of existing lenses.

Olympus has launched an updated version of the Olympus M.Zuiko ED 75-300mm f4.8-6.7. The new version has a new design, better matching the Olympus OM-D E-M5 camera, and also a new lens coating. But the lens is essentially the same. The good news, though, is that the price has decreased significantly.

Olympus M.Zuiko ED 75-300mm f4.8-6.7 II Lens

Sigma has updated their Micro Four Thirds prime lenses. The new lenses appear to have exactly the same optical design, but have a new lens barrel design. In what appears to be a strange design choice, the ribbed plastic focus ring of the original lenses has been replaced with smooth metal rings. From an ergonomic point of view, it is hard to see how this is good news. I'm guessing this was done to make the lenses look more expensive, and to motivate a higher retail price. They are part of Sigma's "Art" line of lenses.

Sigma 19mm f/2.8 EX DN updated

Sigma 30mm f/2.8 EX DN updated

Sigma also launched a new lens, the Sigma 60mm f/2.8 EX DN. This lens is a completely new design, and unlike the Olympus lens with similar focal length and aperture, this one is not a macro lens:

Sigma 60mm f/2.8 EX DN

Sunday, 27 January 2013

Sigma 19mm autofocus comparison

The Sigma 19mm f/2.8 EX DN is perhaps a strange lens. In terms of specifications, it is quite close to the Lumix G 20mm f/1.7 pancake lens, except that it is slower, and less compact. So, why would anyone be interested in it?

Lately, it sells at a reasonable price, and besides, it features the normal internal focus system, while the Lumix G 20mm has an old style focus mechanism which moves all the lens elements, being slow and noisy.

I have found that the Sigma 19mm lens is slightly less sharp than the Lumix 20mm lens, at similar apertures. This is consistent with other people's findings.

With still images

What about the autofocus performance, then? Is it faster, as one could guess? Here is a comparison where I put both lenses on the Panasonic GH2, and focused down to around 0.3m:

The Sigma 19mm lens spends 0.28s focusing down to close to the minimum focus distance, while the Lumix 20mm lens needs 0.64s. So the Sigma lens is indeed faster, as we had expected in advance.

During video recording

Another important aspect is continuous autofocus during video. This is still the achilles' heel of the Micro Four Thirds system, and not even the most recent cameras do this well.

To test it, I mounted the Panasonic GH2 with the Lumix G 20mm f/1.7 lens to a wooden plank, and next to it, mounted the Panasonic GF3 camera with the Sigma 19mm f/2.8 lens. I used Manfrotto Superclamps to mount the cameras, just like when I tested the rolling shutter properties of the GH2 and GH3. I set both lenses to f/2.8 for similar depth of focus properties.

Of course, the 19mm lens has a wider field of view. But on the other hand, the GH2 has the multi aspect sensor, oversized sensor property, which gives relatively wider field of view in video compared with the non-multi aspect sensor GF3 camera. So the field of view is probably quite similar for the two cameras.

Here are the two video footages, combined to one clip. To see the focus performance, it is best to view this in 1080p, click on the youtube icon to access this possibility.

The results are not completely consistent, but I think the Sigma 19mm lens and GF3 combo keeps the focus better during the video. One could speculate that the GH2 probably has the better image processing technology, and hence, should have the advantage in terms of handling continuous autofocus. Despite the handicap of being combined with the basic GF3, the Sigma lens performs better.

It would have been better to mount the lenses to the same camera, of course, but I don't have two of the same camera model. Also, I would normally have used the newer GH3 camera, but my camera is sent back for repair. I hope I get it back soon, and that I don't have to wait for three months, like I had to when sending back the Lumix G 14-42mm lens for misaligned aperture diaphragm blades.


What this shows, is that the Sigma 19mm f/2.8 EX DN lens is better for video use, as long as you can live with the f/2.8 aperture. While it is not as sharp as the Lumix G 20mm lens, it is still very sharp, and certainly more than sharp enough for video use. The autofocus is also less audible.

Even if the Sigma 19mm lens is larger, it is still quite non-obtrusive, with a matte black finish.

The Lumix G 20mm f/1.7 pancake lens is a classic Micro Four Thirds lens, praised for the very good sharpness. However, people also find it annoying for the slow and noisy autofocus performance. People have also reported that the focus mechanism can be clogged with dust, due to the moving front elements. The Sigma lens has no moving lens elements on the outside (only internally), and is probably more solid in that way.

Given the low price the Sigma 19mm f/2.8 EX DN sells at, it can be considered a good value for money, and an interesting alternative to the Lumix G 20mm f/1.7.

I haven't tested the "brother" lens, the Sigma 30mm f/2.8 EX DN in the same way, but I would guess that it, too, performs well in terms of autofocus speed.

Friday, 25 January 2013

GH3 rolling shutter examples

The Panasonic GH3 has a very useful feature, the electronic shutter. One disadvantage of the function is that it suffers from quite severe rolling shutter artefacts. Read more about it here.

Here are some example images, taken with the electronic shutter, the mechanical shutter, and a still image from the video output:

Electronic shutter (f/1.7, 1/250s, ISO 200):

Mechanical shutter (f/1.7, 1/250s, ISO 200):

Video still image:

We see that the electronic shutter has a slower sequential readout than the video mode. This is unlike the Panasonic GH2, which used the video output for the electronic shutter mode, and they shared the same rolling shutter properties. But then again, you only got a 4MP image with the GH2 electronic shutter mode, and it was quite unsharp, probably scaled up from 1080 lines or thereabouts.

This will be my last Panasonic GH3 related article for a while, and the review I am writing will be delayed. The reason is that I have delivered the camera for a warranty repair: The automatic switching between the LCD and EVF suddenly stopped working.

My GH1 and GH2 have operated flawlessly for years. It is perhaps ironic that the GH3 was my first Panasonic camera to require a repair, since it is marketed as being extra solid and weather proof.

The last time I had a Panasonic item for repair, due to uneven aperture diaphragm blades, they kept the lens for three months. And when I did hear from them, they just gave me a brand new lens, which turned out to exhibit exactly the same problem.

I'm hoping they don't keep my GH3 for as long.

Wednesday, 23 January 2013

Sharpness comparison: 19mm vs 20mm

Sigma recently launched to Micro Four Thirds lenses, the Sigma 19mm f/2.8 EX DN, and the Sigma 30mm f/2.8 EX DN.

I have previously been quite happy with the sharpness of the 30mm lens, so I am curious to see how the 19mm lens performs. It makes sense to compare it with the Lumix G 20mm f/1.7, with a similar focal length.

The test images were taken with the GH3 camera at ISO 200, on a tripod, and with self timer. The focus was set on the centre of the frame.

Lumix G 20mm @ f/2.8Sigma 19mm @ f/2.8

Here are 100% crops from the centre of the image frame at various apertures:

And from the lower left corner:


We see that the Lumix G 20mm f/1.7 has an impressive level of sharpness, even wide open. The Sigma 19mm, on the other hand, needs a bit of stopping down before reaching the same level of sharpness. At f/2.8, the 19mm lens is a tad bit dull, even in the centre of the image frame.

This finding is consistent with other tests I have seen. Generally, it is observed that the Sigma 19mm lens is not the sharpest at f/2.8, and improves when stopped down to f/4 and f/5.6. Stopping down beyond f/5.6 does generally not add anything to the overall sharpness, but does give you more depth of focus (DoF). If you need a deep DoF, it may still be wise to stop down to f/8 or even further, but this will give you slightly worse sharpness at pixel level.

Still, it makes sense to say that both lenses are sharp. Comparing the Sigma lens with the Lumix G 20mm f/1.7 is perhaps a bit unfair, since the latter is known to be very sharp. For most uses, the Sigma lens is certainly sharp enough.

On the positive side, the Sigma 19mm f/2.8 EX DN appears to handle flare a tad bit better. There is less flare effects around the strong highlights.

My experience also confirms that the Sigma 19mm f/2.8 EX DN has a much better autofocus performance. The focus operation is also less noisy.

Sunday, 20 January 2013

Lumix 20mm lens and banding with the GH3

Recently, there has been a lot of talk about banding at high ISO with the Olympus OM-D E-M5 and the Panasonic GH3 in combination with one single lens, the Lumix G 20mm f/1.7. This is in fact also mentioned in the GH3 manual, "Stripes may appear in High ISO sensitivity [with the Lumix G 20mm]."

To test this, I took the same image using the Lumix G 20mm f/1.7 and Lumix X PZ 14-42mm f/3.5-5.6 @ 20mm. Both lenses were used on the GH3 camera, at f/5.6, with ISO ranging from 200 to 12800.

Lumix G 20mm f/1.7 pancakeLumix X PZ 14-42mm @ 20mm

To investigate the banding problem, I have made 100% crops from the images at the ISO values 200-12800. Click to enlarge the image:

Based on these images, it is not easy to find any systematic difference between the Lumix G 20mm and Lumix X PZ 14-42mm lenses.

According to other people's findings, this problem can be seen in the shadows at high ISO. So, here are two more crops at ISO 12800, f/5.6, 1/80s:

Perhaps one can say that there is some more systematic banding with the 20mm lens, but it is certainly very hard to see. I don't think there are any significant stripes in the left image.

I tried a second shoot at ISO 6400, this time with the Lumix G 14-42mm f/3.5-5.6 as the alternative lens. The exposure parameters are: 1/60s, f/5.6.

Lumix G 20mm f/1.7 pancakeLumix G 14-42mm @ 20mm

And a comparison at 100%:

Again, I don't see any problems with banding when using the Lumix G 20mm f/1.7 lens.

Finally, here is a comparison with the Sigma 19mm f/2.8 EX DN lens, with a similar focal length:

Lumix G 20mm f/1.7Sigma 19mm f/2.8 EX DN
@ ISO 6400, f/5.6, 1/6s@ ISO 6400, f/5.6, 1/6s

And here are 100% crops at both ISO 6400 and 12800:

The images are a bit dark, so I tried to use the curves tool to bring out more details:

In terms of banding or stripes, I am not able to see any significant difference between the two lenses. I can't see any significant banding when using the Lumix G 20mm f/1.7 lens.


Here is an example video using the Lumix G 20mm lens on the GH3 at ISO 3200. I don't see any banding issues here:

Source of the problem

There has been some discussion about why banding problems were experienced with the Lumix G 20mm f/1.7 lens exclusively. Some have suggested it may be due to the focus construction of the lens. It is one of the very few Micro Four Thirds lenses which has a traditional focus mechanism, in which all the lenses move back and forth. This takes a stronger motor, and is slower and more noisy than internal focusing. The lens also has a large spiral spring in the focus assembly, and a lot of people have suggested that this might be the source of the problem.

Since the banding issue has been seen on the Olympus OM-D EM-5 and Panasonic GH3, some think this is a sign that their sensors are related, and share vital parts.

Also, it should be noted that if you use the electronic shutter option with the Panasonic GH3 in combination with fluorescent light (indoor), you may get banding with certain shutter speeds. There is an easy to understand explanation for this: Fluorescent light flickers with a frequency of 100Hz or 120Hz (depending on the country), and the electronic shutter reads out the imaging sensor sequentially during about 1/10s. Hence, a shutter speed faster than these shutter speed will give you significant banding. Read more about this here.


In my tests, I have not been able to find any significant negative effects due to banding with the Lumix G 20mm f/1.7 lens. My conclusion is that it is safe to use this lens, also at high ISO.

On the other hand, I have seen people posting example images where the banding problem can be seen, so I don't doubt that it can be a problem.

Another conclusion is that the ISO 12800 image quality of the GH3 is quite good. There is a lot of noise, of course, but still an amazing level of details. For web use, the images are usable.

Sunday, 13 January 2013

Sales statistics from Japan

BCN Ranking publishes sales statistics for various categories of cameras in Japan. Last year, I made a summary of the system camera category, which includes both mirrorless sytems and DSLRs. We saw that Micro Four Thirds had reached a healthy 19% of this category by the end of 2011:

For the 2012 statistics, BCN Ranking has split these into two categories: DSLRs and mirrorless. This makes sense, of course, but the downside is that I cannot continue my time series of statistics. BCN only give the percentage of sales, not the absolute number, hence I cannot recombine the two categories.

Anyway, let's see what the 2012 statistics for the mirrorless category looks like:

And when summing up per camera system:

Just like the previous statistics, these are based on the twenty most sold camera models. This means that you cannot expect the percentages to add up to 100%. There is still another 9% missing. In the missing category, I would expect that you find cameras like the Panasonic G5 and GH2, among others.

Micro Four Thirds has a very healthy lead in the mirrorless camera category, at 50% market share. I would attribute this to the fact that they launched their system early, and have a lot of quality lenses out.

One could expect to find the Samsung NX system on the list. On the other hand, it is fair to say that there is some rivalry between Samsung, which is a Korean brand, and the other manufacturers on the list, which are Japanese. While Samsung does not sell well in Japan, I think they do better in other markets, like Europe.

The Nikon 1 system is already at a good market share of 13%. They have a very strong brand in Japan, and have invested heavily in marketing. The volume models, the J series, look cute, with various colour schemes, and a clean design with geometric shapes.

The Pentax Q system er quite odd, in my opinion, with a very small sensor size. At this sensor size, I think most people are better off buying a premium compact camera, like the Panasonic LX7 or Olympus XZ-2.

Pentax K-01

The Pentax K-01 is also an odd machine. It shares the lens mount with the Pentax DSLR cameras. Hence, it is a mirrorless camera with the register distance of an SLR. While sharing the lens mount has some advantages, it also means that there is little size advantage to the mirrorless system. Because the camera needs to be as large (except for the pentaprism), and the lenses cannot benefit from a shorter register distance.

Monday, 7 January 2013

From the competition

While I use the Micro Four Thirds system myself, there is no denying that I watch what is happening in the competition. Here are some of my personal reflections on the market.

Premium compacts

Back in the mid 2000's, Panasonic ruled the premium compact segment with their LX series, along with the Leica branded versions of the same cameras. Other brands also wanted a part of this cake. Canon re-launched their S-series, with S90, S95, and so on.

Recently, Samsung broke the f/1.4 barrier with their EX2F premium compact with a 1/1.7" sensor. However, it was not long until Panasonic trumped this with LX7, with an even longer zoom range, and a larger aperture in the long end to boot. How could Panasonic pull this off, given that both use a 1/1.7" sensor?

Samsung EX2FPanasonic LX7

Sunday, 6 January 2013

GH2 vs GH3 rolling shutter evaluation

The Panasonic GH1 and GH2 had pretty much the same rolling shutter properties. I have previously examined the rolling shutter artefacts of the GH3, compared with the GH2, and found that the GH3 has somewhat less artefacts. But my test was based on a rotating propeller setup, which is not so realistic.

Rolling shutter artefacts are typically identified when panning quickly during video recording. This can lead to "wobbly" effects, square objects can be seen to lean towards one side.

To compare these artefacts again between the GH2 and GH3, I mounted both cameras to a piece of wood:

I used Manfrotto Superclamps with ball heads to fix the cameras to the piece of wood. These are quite useful.

Wednesday, 2 January 2013

Lumix X 12-35mm f/2.8 review

The Panasonic Lumix X 12-35mm f/2.8 is a premium standard zoom lens. It was released in 2012, but obviously intended as the kit lens for the high end GH3 camera released later the same year. The lens is show below, together the with basic Lumix G 14-42mm f/3.5-5.6 kit zoom lens:

Tuesday, 1 January 2013

Geometric distortion correction

Micro Four Thirds lenses tend to be smaller than lenses from other systems. There are several reasons for this.

One is of course that the sensor is smaller than most other system cameras, with the exception of the Nikon 1 system, which has an even smaller sensor. Another reason is that the register distance is shorter than for DSLR systems.

But one major reason is that the system relies on software correction of the sensor output. This includes correction of Chromatic Aberration (CA) artefacts and vignetting.

Most of the Micro Four Thirds lenses need geometric distortion correction applied for the output images to become rectilinear. This is done totally seamlessly by the camera and software, both for JPEG and RAW images. So the user never notices that the image, as seen by the camera through the lens, is not rectilinear in the first place.

This is in contrast to older DSLR systems. In these systems, there is an optical viewfinder, in which the users sees exactly what the sensor sees, through the lens. With a DSLR system, the lens must be rectilinear, otherwise, the user will be appalled by the geometric distortion when using the camera.

Here is an illustration of two basic kinds of distortion: Pincushion distortion (left) and barrel distortion (right):

In reality, the geometric distortion might very well be more complicated than what is illustrated by these simple models.

In this article, I look at another type of correction employed in two of the newer lenses, geometric distortion correction. By looking at the RAW file in a third party program, I can extract the uncorrected image, and compare it with the out of camera (OOC) JPEGs. For a good reference, I photographed a wall with square tiles:

After processing the RAW image to find the true geometry of the underlying image, I superimposed the two, using red lines for the uncorrected geometry, see below.

I included the appropriate adjustment needed. The adjustment numbers in percent refer to the "Lens Distortion" filter in The Gimp, an image processing software. Of course, to become rectilinear, some lenses might require more complicated adjustment than the simple model given by the "Lens Distortion" filter. So these figures are just intended to be approximate relative indicators of the degree of distortion. A positive figure indicated barrel distortion, while a negative figure indicates pincushion distortion.

Lumix X 12-35mm f/2.8

This lens features some barrel distortion in the wide end, and no distortion correction in the long end. However, even after the in-camera distortion correction, there is some residual barrel distortion in the wide end. This is the most pronounced at close focus distance, but can also be seen with infinity focus, in my experience. It is not uncommon that the geometric properties change slightly with focus for internal focus lens designs.

See the review of the lens for a real life example illustrating the barrel distortion in the wide end.

Also in the long end, the out of camera JPEG images show some distortion. They tend to have a bit of pincushion distortion.

Lumix X 12-35mm f/2.8 @ 12mm: -14%

Lumix X 12-35mm f/2.8 @ 35mm: 0%

Lumix X PZ 14-42mm f/3.5-5.6

It is perhaps unexpected to see that this lens has less barrel distortion correction in the wide end than the basic version of the lens, the Lumix G 14-42mm f/3.5-5.6 kit zoom lens. Given the smaller size of the power zoom version, one would expect that more optical compromises have been made.

Just like with the Lumix X 12-35mm f/2.8 lens, there is some residual barrel distortion even in the corrected image at 14mm. There is also some residual pincushion distortion in the long end.

Lumix X PZ 14-42mm f/3.5-5.6 @ 14mm: -15%

Lumix X PZ 14-42mm f/3.5-5.6 @ 42mm: +5%


I'm a bit disappointed to see that there is noticeable barrel and pincushion distortion in the images produced by the premium Lumix X 12-35mm f/2.8 zoom lens. For such an expensive lens, one would have expected more perfect images.

On the other hand, this is not really any real problem. If you need to have absolutely rectilinear images, then you can apply a bit of lens distortion post processing. Also, I guess this comes down to a compromise between having a traditional focus mechanism, which is slower, but more resistant to distortion at closer focus distances, and internal focus, which is much faster. The Lumix G 20mm f/1.7 pancake lens has the traditional focus mechanism, and quite some people dislike it for the slow and noisy autofocus.

Summary of other lenses

And here is a summary of the adjustments to all the lenses I have tested. The percentage in the table refers to the Gimp image processing Lens Distortion filter value needed to make a rectilinear image: 0% means no correction, a negative value means barrel distortion, and a positive value means pincushion distortion.

LensFocal lengthRelative distortion correction
Leica DG Summilux 25mm f/1.425mm-8%
Lumix G 20mm f/1.7 Pancake20mm-11%
Lumix G 14mm f/2.5 Pancake14mm-16%
Lumix G 14-42mm f/3.5-5.614mm-18%
Lumix G 14-42mm f/3.5-5.630mm0%
Lumix X PZ 14-42mm f/3.5-5.614mm-15%
Lumix X PZ 14-42mm f/3.5-5.642mm+5%
Lumix X 12-35mm f/2.812mm-14%
Lumix X 12-35mm f/2.835mm0%
Lumix G 7-14mm f/47mm-17%
Lumix G HD 14-140mm f/3.5-5.6 II14mm-16%
Lumix G HD 14-140mm f/3.5-5.6 II50mm0%
Lumix G HD 14-140mm f/4-5.814mm-17%
Lumix G HD 14-140mm f/4-5.830mm-4%
Lumix G HD 14-140mm f/4-5.850mm-1%
Lumix G 45-200mm f/4-5.645mm+1%
Lumix X PZ 45-175mm f/4-5.645mm0%
Lumix X PZ 45-175mm f/4-5.6100mm+5%
Lumix G 100-300mm f/4-5.6100mm0%
Olympus M.ZD 45mm f/1.845mm0%
Panasonic Leica Lumix DG Macro-Elmarit 45mm f/2.8 1:1 Macro45mm0%
Lumix 8mm f/3.5 fisheye8mm0%
Sigma 30mm f/2.830mm0%