Many people are looking for camera systems that can give a thin depth of focus (DOF). With a thin depth of focus, objects that are beyond the focus distance, or closer, are out of focus.
The Micro Four Thirds system is not ideal for getting thin DOF. To get a thin DOF, you are better off buying a camera with a large sensor, for example full frame DSLR cameras.
I took the same picture using the three lenses at various apertures. Here are the full images at maximum aperture:
Lumix G 14mm @ f/2.5
Lumix G 20mm @ f/1.7
Lumix G 14-42mm @ 14mm f/3.5
Lumix G 14-42mm @ 20mm f/4.1
The focus was set on the emblem on the bell in the middle left part of the image. I used the Panasonic GH2 at base ISO, and the shutter speed was around 1-6 seconds. I used a tripod, and also two second shutter delay, to avoid camera shake.
The images above are taken using the maximum aperture available with the given lens. Hence, the DOF is as thin as possible, given the focal length and focus distance.
To better evaluate the bokeh, I have made 100% crops from two parts of the image (click to enlarge):
The first crops are from the focus area. From these images, it could look like the 14mm pancake lens is unsharp. However, these images were taken primarily to evaluate the bokeh, not the sharpness, and the focus point might be slightly different between the lenses. In my experience, the sharpness of the 14mm pancake lens is rather good.
In the seconds image, we see the out of focus highlights. I suppose one could say that neither of the lenses give a very nice bokeh. They have various problems. They all exhibit some ringing, but it seems to be worst at 14mm. Also, the bokeh is uneven, and "dirty", "swirly".
The 20mm pancake lens shows the most non-circular highlights, both wide open and closed down.
The 14-42mm lens shows some strange irregularity at f/5.6, at both 14mm and 20mm. This could look like a construction error of the aperture diaphragm. However, it is not likely to pose much of a problem, since only at very close focus distance would you see much out of focus rendering at f/5.6
In terms of roundness, the 14mm pancake has the most consistent appearance.
Back in the day when people started replacing CRT computer monitors with LCD panels, dead pixels was a big deal. When you received the LCD panel you had ordered, you would have to review it to find the number of dead pixels, and consider whether or not to return it. Some claimed that dead pixels could be massaged with your fingertip and revived. After the production process improved, though, dead pixels has ceased to be a problem with computer monitors.
With camera sensors, the number of pixels is counted as the number of individual dots, each capable of seeing only one of the primary colour. Generally, these pixels are arranged in a Bayer-pattern, with two green pixels for each red and blue:
So a camera with 12 megapixels has 12 million individual light measuring cells, three times as many as the dots on a typical computer monitor. So is dead pixels a problem with cameras?
I tested my Panasonic GH1 camera. I took one very underexposed picture (which turned out black) and one very overexposed picture (which became white). The JPEG images are here, straight from the camera:
You don't need to look at them, though. Trust me, they are completely even, with no signs of dead pixels whatsoever.
However, what if the camera corrects the dead pixels in the JPEG files it generates? Perhaps there are "holes" in the image data, which is filled in by the JPEG engine in the camera's algorithm.
To check this, I opened the RAW files in a third party RAW converter program, the UFRAW. This did in fact reveal some dead pixels. I found eight pink dots. The colour pink is due to the green sensor element being dead, I suppose.
In the image below, a pink ring has been put around the dead pink pixels. After scaling the image down to 1000 pixels wide, the dead pixels themselves are of course not easy to spot anymore.
When investigating the black image in the RAW converter, I found no evidence of stuck pixels. So no pixels were generating a "phantom" light even though the exposure was non-existent.
I looked at other exposures, and found the dead, pink pixels in the same spots. So these pixels are definitively permanently dead on my GH1 camera.
Is this a problem? Hardly. As we saw, the JPEG engine is clever enough to mask these dead pixels, so when using JPEG images out of the camera, don't worry.
When using the RAW images, though, the dead pixels might disturb the image when using high resolution prints, for example. I would guess that the supplied RAW conversion program fixes these problems automatically, so this is likely only to be a potential problem with third party converters. And even then, eight dead pixels out of a total of 12 million is not exactly a huge percentage. It is very unlikely that this will cause any unwanted side-effects.
Appendix
Panasonic G series cameras do have a function to map these dead pixels. To do so, use the function "Pixel Refresh", which can be found in the custom menu (on the last page). The custom menu is the one with the "C" and wrench icon.
The Lumix G 8mm f/3.5 fisheye lens is fun to use, due to it's extremely wide perspective. This type of lenses are commonly used in extreme sports videos, like skateboard and BMX. I don't do this type of things myself, but I figured I could use the lens to record myself bicycling anyway.
To do this, I attached the Panasonic GH2 camera to the front fork of the bicycle. I used a Manfrotto Super Clamp, which is essentially a clamp with a tripod head attachment stud. To be able to attach the camera, I also used a tripod ball head, and I chose the Benro BH0, which is pretty compact. After putting it on my bicycle, it looks like this:
Here's the video I recorded:
I prefocused at about 50cm, and set the camera to Manual Focus (MF) before starting the video recording. This was done to avoid focus hunting during the video. The 8mm fisheye lens focuses very quickly, but still, I wanted to avoid short periods of out of focus footage.
I think the colours look a bit dull in this video. It was a somewhat dull day, but still, I think that the next time, I will increase the colour saturation setting before using this lens for videos.
A matter of some dispute is which camera gives the best video quality: The hacked GH1 or the newer GH2.
The GH1 has earned some popularity due to the possibility to change the firmware. Adjusting the firmware is generally referred to as "hacking" the camera. There are many options, and the most useful ones are the possibility to get native 1080p 25fps (with the PAL version), and to increase the bitrate. I have done both with my GH1.
I've compared them before, and my conclusion back then was that the GH2 had better auto white balance (AWB) for indoor lightning, but other than that, it was hard to find much evidence of better video quality. I was advised that I should try to pan the cameras while recording foliage.
There are two problems with that: One is that there is no foliage in Scandinavia at this time, since spring is not yet here. The other is: How would I know that I have panned at the same speed, giving comparable footage?
For the second problem, Technic LEGO again comes to the rescue. Previously, I made a rotating object using Technic LEGO, and video recorded that. This time, I made a platform for the camera out of Technic LEGO, and used that to pan the cameras at the same speed. Here is how the platform works:
Putting the platform outdoors enabled me to record the same footage using both cameras. I used the same image parameters for both cameras: ISO 200, f/3.2, 1/400s shutter speed, outdoor sunny white balance, manual focus. Due to limitations in the cameras, I could not use the same frame per second count. I used 1080p for both, but 25fps for the GH1 and 24fps for the GH2.
I used the Lumix G 14mm f/2.5 lens, which is more than sharp enough for this test.
In real life use, one would not normally use a shutter speed of 1/400s. The normal speed to use is twice that of the framerate, which is 1/50s in my case. This is called a 180° shutter, since it is open half the time on average.
One reason why a 180° shutter is normally used, is to get motion blurring for objects moving across the frame. Without motion blurring, the movement can look unnatural on film, since the object will appear as if it materializes in different spots at different times. This is confusing for the person watching. I have a discussion about this, and the need for Neutral Density (ND) filters here.
In my case, though, I want to avoid motion blurring. The whole point of the experiment is to see which camera resolves the most details, and then I must make sure that the video stream contains as much details as possible to begin with. Motion blurring typically makes the footage softer.
Due to the hacked GH1 having a higher bitrate, it generated larger video files. The GH1 gave 5.4 MB/s, while the GH2 gave 2.8 MB/s.
Here are the two video recordings:
GH1
GH2
It's somewhat difficult to evaluate the quality of the video by looking at the videos, especially since YouTube compresses them anyway. So to aid in comparing them, I have grabbed single frames from them to compare.
Here are two similar frames (click for larger versions of them):
GH1
GH2
The first thing we can see, is that the GH1 still image is brighter, despite having the same image parameters. I interpret this to mean that the ISO scales of the cameras are not the same: The GH1 ISO scale corresponds to higher ISO values with the GH2. It is a well known and documented fact that the GH1 ISO scale is generous, meaning that a given ISO value gives more sensitivity than the same value for comparable cameras. The GH2 ISO scale is more normalized.
Here are direct comparisons between two areas from the two video streams. They are shown here in 100%, i.e., not rescaled and not sharpened.
Since the exposure is slightly different, I have also done an autolevels on the images, to make them comparable. Here they are:
Conclusion
One could be tempted to think that the GH1 gives better video quality, due to the twice as high video bitrate. But the GH2 has other advances. We don't know for sure just how the GH2 handles the video compared with the GH1, but it is reasonable to guess that it samples more pixels as a basis for the video output, and that the compression algorithm is better.
So, which video stream is better in my test? I think they are quite similar. Perhaps one can conclude that the GH2 gives somewhat better contrast and sharpness. The GH1 has slightly washed out colours, I think. But the difference is small.
My conclusion so far is that the GH2, even with lower bitrate, gives slightly better video quality. But both cameras are very competent.
3D is popular nowadays. Panasonic have launched their first 3D lens, which is probably not very useful. It only works on newer G-series cameras, and can only be used for stills, not video. And the stereo base, the distance between the two lenses, is only 1 cm. This is suitable for macro images, but too small for most other uses.
If you're photographing still objects, you can take 3D like images with your normal gear. It's just a matter of taking two images with the camera spaced some distance apart.
In fact, this is quite easy if you have an Arca Swiss style quick release plate. This enables some sliding from side to side when the camera is mounted to a tripod. Here is a picture of the Panasonic GH1 with a quick release plate mounted. On the table is another similar plate:
The plates on the picture are not actually produced by Arca Swiss. They are named Benro PU-60.
Using the quick release plate to offset the camera, I obtained these two images of the same subject. The stereo base is about 3cm. The video shows how easy it is to slide the camera sideways for taking the stereo images:
To avoid having different exposures in the two images, I set the white balance (WB) manually. I also used Manual (M) exposure, and set the shutter and aperture manually.
Now, the next task is to compile these two images into one single image suitable for stereo viewing.
One way is to use different colours. The image must then be viewed using 3D glasses with different colours. I used the Gimp script "script-fu-make-anaglyph", which does this very quickly. Here is the stereo image for cyan/red glasses:
For red/blue:
And for red/green:
Another way to view the stereo image, is to place them side by side as a pair. This is called cross-eye viewing, and takes some practice. You need to look at the left hand image with your right eye, and at the right hand image with your left eye.
Click on the image below to see it enlarged on your screen. Put your finger between your face and the computer screen, about 10-20cm from your eyes. Then focus on your finger, and see that the two images merge and become three. Focus on the centre image. If you can do this, it can be quite rewarding, as the stereo effect is very good.
Yet another way, is to compose the two images into an animated GIF:
And here is an animation consisting of three separate images:
Conclusion
This method works well with images of still life. But for moving objects, it is of course impossible to take the same image twice. And the same goes for videos.
Just how to present the 3D images is, as far as I know, not well standardized.
Panasonic Lumix G cameras do not come with any remote receiver. Neither infrared (IR) nor radio frequency (RF). I like to have the possibility to trigger the shutter remotely, and so I have been searching for an appropriate remote shutter release.
Of course, there's always the self timer. But it is more of a hassle to use, and it doesn't give you any control over the autofocus.
I have previously tried the JJC JR series Infrared Controller. While it does do the job, it is awkward to use, somewhat unreliable, and has a poor build quality. Also, since it is an IR controller, you need to point the remote towards the receiver.
So I was not happy with the JJC JR remote.
I decided to try an RF remote from Pixel, called "Pixel RW-221 Wireless Remote Control". It is made for the Panasonic G series, as well as the older Panasonic DSLR cameras.
When unpacking, it is immediately clear that this is a higher quality product than the JJC JR remote. The parts have a better look and feel, and the buttons operate better. Also, the cord is spiraled, and has gold plated contacts. It comes with batteries, two sets of two AAA units. Here are the contents:
Clockwise from top left: Spiral cord with 2.5mm jack connectors, the remote receiver with a power button, and a shutter release button, the wireless remote control, batteries (4xAAA), and the operation manual.
The following picture shows the two units open, with batteries installed. You can see the dip switches, which are used to change the RF frequency. This is useful if you have several units, or if your neighbour has the same product.
If you are practical, like me, you can operate the unit without reading the manual. It is very intuitive. The video shows how to use the remote:
The remote is used on a Panasonic Lumix DMC GH1 in the video above, but should work with all Panasonic G series cameras. I have confirmed that it works with the Lumix GH1, GH2, and GH3. The latter has a separate remote control socket, not combined with the mic. It also works with the Lumix GX1, GX7, G5 and G6. The Lumix GM1 does not have a remote control socket, and cannot use this remote.
The right angle plug goes into the camera, and you must make sure to insert it fully. Some times, this requires pushing it in quite hard.
The remote receiver unit doesn't need to sit in the flash socket. But as long as you don't need to mount a flash, it is a practical place for it to stay. When pressing the power button, the red LED flashes to indicate that it is on.
The remote shutter can be half pressed for focus, and pressed fully for triggering the shutter.
There is an auxiliary shutter button on the receiver unit, which works in the same way.
I could not get the Bulb mode to work. It appears to trigger the shutter quickly over and over again. So if you need the Bulb mode, this remote might not solve your needs.
Just for the fun of it, I decided to see if there was any patterns to be found when it comes to lens pricing. I used the US prices, since the US is a big market.
First, one might think that weight is important. After all, glass is heavy, and also expensive to produce. Here is the relationship between the lens weight in grams and price in dollars:
We see rather easily that there is a relationship between weight and price, but it's hardly significant (R2=0.28). There are many outliers, for example the 45mm macro lens, and the 45-200mm tele zoom.
One could also guess that fast lenses are more expensive. So let's look at price versus the maximum aperture of the lens:
What we see, though, is the opposite. Faster lenses are less expensive. However, this is because some of the slower lenses are expensive special lenses, like the wide angle zoom Panasonic Lumix G 7-14mm f/4. We also have long zooms and superzooms in this category. Again, the fit is not very good, R2=0.06.
It is quite obvious that to explain the price, we need to include several parameters, not just the weight or the aperture.
One way to identify interesting variables, is to use Principal Component Analysis (PCA). This is a way to find which variables that best cluster the observations. Here is a plot of the first two principal components:
What we see here, is not surprising, but the presentation is somewhat interesting. First of all, we see that the pancake lenses are fundamentally different from the rest, as they occupy one large part of the image.
Another binary variable is premium. I've put the Lumix 45mm macro, the Lumix 14-14mm HD superzoom, and the Olympus 75-300mm tele zoom lens in this category. However, this variable does not appear to be important in grouping the lenses. It is correlated with other variables, like length, weight, number of lens elements, lens groups, filter thread, and maximum aperture.
Some lenses are still outliers, like the basic kit zooms (since they are light, but have many lens elements).
However, when using the first two principal components to fit the price, there is still a lot of unexplained variation:
Conclusion
What this all boils down to, is that there are too few observations. With more observations, i.e., more lenses, we might be able to fit the price to lens characteristics in a better way. And this is a conclusion we all can agree with, I am sure, that we need more Micro Four Thirds lenses.
Essentially, ETC is a digital zoom for video. During normal video recording, the entire sensor area is scaled down to 1920x1080 pixels. When enabling ETC, the camera crops the 1920x1080 pixels from the centre of the sensor. This achieves full HD resolution, as well as a digital zoom. See the illustration:
Since 2800/1080 = 2.6, the ETC mode gives a tele conversion effect of 2.6x. If you use the 720p video mode, the conversion effect becomes larger still, 2800/720 = 3.9.
A question that remains is to see if the video quality is still good using the crop mode. In theory, it could be somewhat worse, since the camera doesn't have the option of scaling down from a larger number of pixels.
On the other hand, we know that the camera doesn't actually sample all the 16MP of sensor pixels for each frame in the video. That would require too much bandwidth and processing power. Just how many are sampled is unknown, but given that the electronic shutter 40fps continous mode has 4MP, one can guess that about that many are sampled during video recording. This is, of course, just speculation.
To study this, I have used the kit zoom lens, Lumix G 14-42mm f/3.5-5.6. Since it has a zoom ratio of 3x, using ETC in the short end should give the same field of view as the longer end without ETC. This is a good basis for comparing the video with and without ETC.
I used 40mm without ETC, and 15mm with ETC. Since 15mm times 2.6 is approximately 40mm, these two modes give about the same field of view. I recorded video using ISO 160, 640 and 2500. Here are the recordings in sequence:
To better evaluate the quality differences, I have compared still images from the video streams (click for a larger version):
It appears that the video stream recorded using ETC has worse image quality than the normal stream, at all ISO values. There is some lack of sharpness and contrast, and more noise in the ETC video streams.
The reasons for these differences could be the sampling from a higher number of pixels when not using the ETC mode, as discussed above. Or it could also be related to the lens sharpness, see the discussion in the Appendix, below.
This does not mean the the ETC videos are useless, far from it. But it is fair to say that there is some image degradation when using ETC. As a rule of thumb, I think you should avoid using ISO higher than 640 when using ETC.
ETC is still a very good tool to use when you need extra reach during video recording. If you don't have any longer lenses, ETC is the only way to get quality videos at longer reach.
Appendix, some technical aspects
I used the new 1080p, 24fps cinema mode. This is the video mode on the Panasonic GH2 which gives the highest bitrate. It is generally recommended to use this 24ftp progressive mode, except when you have significant movement in the picture frame. When there is movement, people generally recommend to use the 60fps (NTSC) or 50fps (PAL) modes.
When the lens was set to 15mm, I stopped down the aperture to f/4. In ETC mode, the camera only uses the centre of the image, where lenses are generally very sharp. I've previously looked at the sharpness of the Lumix G 14-42mm kit lens, and found it to be good wide open at 14mm. So I don't think the centre sharpness at 15mm f/4 is a significant limiting factor when using the ETC mode.
But there is probably some impact on the sharpness due to the lens performance when using ETC. Remember that the ETC mode is more demanding on the lens sharpness, since there is no downscaling. When video recording without ETC, the image is downscaled from a larger sensor area, and the lens doesn't need to be tack sharp. It is like putting the lens designed for a 16MP sensor on a 2MP sensor camera. It's not very likely that you can identify a lack of sharpness with a 2MP sensor.
In real life use, it is of course silly to use ETC in the short end of the Lumix G 14-42mm f/3.5-5.6 kit zoom. It is better to just zoom in. But I did this to get comparable images with and without ETC.
It is much more relevant to use ETC with the longer end of the Lumix G 45-200mm tele zoom lens. However, many have concluded that it is not very sharp in the longer end, so it may not be sharp enough to get a good video quality with ETC. You may want to stop down the aperture to f/6.3 or f/7.1 for the best result.
Many Micro Four Thirds lenses feature in-camera geometric distortion correction. Two examples are the Panasonic pancakes, Lumix G 14mm f/2.5 and Lumix G 20mm f/1.7. Both have pretty similar distortion correction needs. When converting the sensor output to the out of camera JPEG image, around 10% of the pixels in the border area are lost.
This is somewhat controversial. Some feel that a quality lens should not require further software correction. In fact, the lack of geometric distortion is a traditional sign of a high quality lens.
I think that this is mostly a non-issue. By allowing some aspects of the image to be adjusted in software, the lens designers can focus on issues which cannot be corrected in post processing. This has the potential of making the lenses better, at a smaller size, and potentially a smaller cost. Panasonic Micro Four Thirds lenses are adjusted for geometric distortion and some chromatic aberrations. The geometric distortion is also corrected in Olympus Micro Four Thirds cameras. At this time, though, Olympus does not correct chromatic aberrations.
To illustrate the geometric distortion done with various lenses, I have photographed a tiled wall with them, and shown the sensor output compared with the corrected JPEG output.
Note that this is in no way a criticism of using RAW images. There are many RAW image converters which will do the distortion correction automatically and seamlessly, and you will never notice that there was any geometric adjustment done at all. I am using the RAW images to visualize the initial image captured by the sensor, as it is the only way to access it.
Here is a comparison of the uncorrected and corrected images for some lenses. Since I am only interested in the geometric distortion, I have increased the contrast so that the images become monochrome. I also superimposed the corrected out of camera images (black) onto the original uncorrected images (red).
I have also included the appropriate adjustment needed. The adjustment numbers in percent refers to the "Lens Distortion" filter in The Gimp.
Normal zoom lenses pretty consistently feature barrel distortion in the wide end. The tele zoom Lumix G 45-200mm appears to have some very small pincushion distortion, but very minor.
