GH2: Buffer flush speed

The Panasonic Lumix GH2 is currently the top Micro Four Thirds camera. Still, it is not a camera with pro features, in my opinion. Of course, there is no firm definition about what constitutes a pro camera. But I would expect to find features like weather sealing, built in remote control receiver, wireless TTL flash control, twin control wheels, all of which are missing on the GH2. Another annoying feature is the slow buffer cleaning speed when using RAW images.

Single exposure

When taking a single exposure and saving both JPEG and RAW images, the delay from taking the image until playback is available is four seconds. I used a SanDisk Extreme Class 10 SD card. See the video below for a demonstration:



As you can see, pressing the PLAY button does not bring up the playback until the buffer has been flushed, which takes four seconds. Without RAW images enabled, this is pretty much instantaneous.

Multiple exposures

Using a fast SD card, the camera can take seven consecutive images in the high speed mode, at 5 FPS, when recording both JPEG and RAW images. But after this, it takes a very long time before you can review the images.

One could speculate that a high quality SD card could be better in this respect than a lesser quality one. I decided to test this, but trying two different cards. Below are two Class 10 SD cards at 8GB each, the premium SanDisk Extreme, and the value Transcend card:

I tested it by putting the GH2 on a tripod, turning off autofocus, and setting the aperture to the max, to avoid any delay caused by changing aperture. I used the Lumix G HD 14-140mm lens.

Here's a video recording of the experiment:



The results speak for themselves. The time from the first picture was taken until the playback was available was: 34.5 seconds (Transcend Class 10), and 24.5 seconds (SanDisk Extreme Class 10).

You can still take more images

While waiting for the buffer to clear, you can still take more images, even if you cannot enable the playback. After the buffer is filled initially, the camera will take one image approximately every third second. So this is not such a huge problem as it may seem like.

Here is a demonstration:



Auto review

Even if you cannot enable playback until some delay, the camera can still show a quick preview after capturing the image. This feature is called "Auto Review". You can find it in the "Setup" menu:

The Auto Review is a simple playback, and does not allow zooming in, for example.

Conclusion

The result surprised me. I was expecting to find that a Class 6 card is sufficient for use with the GH2, and that any faster card is a waste of money. Quite to the contrary, I find that using a more expensive premium Class 10 card actually has some real benefit, when recording RAW images.

Another conclusion is that even with a high end SD card, the buffer flush delay is significant with the GH2. 24 seconds is a long wait. Of course, when taking many exposure one could consider to turn off RAW recording, which would solve the problem.

The Panasonic GH1 has also got a slow buffer clearing speed. I haven't tested them head to head, but they feel pretty similar.

If you only use JPEG images, you don't get these significant buffer clearing times. In that case, you can basically ignore this test.

So do you need to use RAW? I find that if I have a good exposure and the correct white balance, I can use the JPEG image straight from the camera with no problem. But if the exposure is tricky, or the white balance is off, then having the RAW file comes handy for getting the best results. So for low contrast images at daytime, using RAW has little benefits, I'd say.

Home made camera bag

I like the small Panasonic pancake lenses. However, some of the size advantage is lost when putting the camera in a standard sized bag, as most camera bags are too large. I find that camera bags generally come in two categories: For compact cameras, and for system cameras. The former are too small to accommodate the camera with a lens mounted, and the latter are always too large for the camera with a pancake lens.

So what to do? Of course, the solution is to make my own bag. I wanted to make it out of neoprene fabric, a rubber like material commonly found in divers' suits. However, buying neoprene is difficult. So I ended up just buying a laptop case in the desired fabric, and then cannibalizing it for the material:

To get the right shape, I cut a piece of cardboard to fit the camera inside it:

The cardboard template was then used to cut the fabric. The extra flap on the top left side is for a separate, small pocket:

Here I have started sewing together the fabric. I'm testing that the Panasonic GH2 and the Lumix G 20mm lens fit inside:

At this stage, the bag is mostly finished. The zipper is taken from the original laptop bag. There is a smaller pocket in the left side of the bag:

Here, the bag is finished. The strap is stolen from an old backpack:

And here's how it looks when wearing it:

Conclusion

The bag works well, and has room for the camera with a pancake lens. But making it took very long time, and required a lot of sewing.

Bad aperture diaphragm in Lumix G 14-42mm f/3.5-5.6

When investigating the bokeh of some Panasonic Lumix lenses, it came to my attention that out of focus highlights using the Lumix G 14-42mm f/3.5-5.6 kit lens was irregularly shaped when stopped down. I decided to take a closer look, to see what the problem is.

First, I took a picture in which I set the lens to tele (42mm), focused as close as possible, and placed a flashlight in the background. The flashlight renders out of focus. Here is the full image at f/5.6, the maximum aperture. The flashlight is placed in the centre of the image:

To see how the roundness changes when stopping down, I have made 100% crops from the centre at various apertures:

This verifies the problems I saw when studying the bokeh. The out of focus highlights are definitively not circular. It looks like the aperture diaphragm blades are misaligned.

Micro Four Thirds lenses are always wide open when powering the camera down. This means that normally, you cannot look at the diaphragm blades from the inside, since the aperture is wide open.

However, a trick is to stop down the lens, and then remove the camera battery. That way, you can remove the lens while stopped down. This procedure is not exactly recommended by the manual, so use with caution.

Using this trick, I could photograph the back side of the lens when stopped down:

Here it is clear that some of the blades are misaligned. Thus, the resulting image has non-round out of focus rendering.

I've made a video showing the stopping down of the aperture blades. The apertures goes from f/3.5 down to a full close in 1/3 stops.



I filmed it using the Panasonic Lumix GH2 and the Leica Lumix DG 45mm f/2.8 macro lens. To get the needed magnification, I used the new Extra Tele Converter (ETC) mode.

Here's a photo of the setup for capturing the video:

Conclusion

My lens most certainly has a bad aperture mechanism. Whether this is a one-off bad copy, or a systematic problem with the lens line is hard to say. I would guess it's an example of poor quality checking, and that most lenses are ok.

This problem annoys me a bit. I've previously found the basic kit lens to be a good one, despite the mixed reception it generally gets online.

Now, this is not really a big issue. Generally, you don't get much bokeh with kit zoom lenses anyway. So the problem is not very likely to show in images. If using the camera at full auto, it generally chooses the maximum aperture anyway, in which case the aperture opening is round.

This problem might affect the exposure correctness. The defective aperture blades could cause slight exposure irregularities. But again, this is not likely to be a big problem

Epilogue

If found the aperture to be so bad, that I took the lens back to the shop where I bought it in the first place.

The store keeper has some problem verifying that his off the shelf lens did not exhibit the same non-round aperture. I helped him by taking a photo with the lens mounted to the Panasonic GF2 camera at f/9, 2 seconds, and removed the lens during the exposure. Looking towards the light through the lens showed that his copy had a round aperture.

So he accepted my lens as defective, and sent it for repair.

After one month, I started enquiring about the lens. I always got the same answer: "The lens is just around the corner, should be in our store the beginning of the next week."

It was not until after three months that the lens finally did arrive in the store. When I went to pick it up, I was told that they simply replaced the lens with a new one. Why let me wait for three months when they would just give me a new copy?

Coming home, I once again checked if the aperture was rounded. I found that my new lens had exactly the same problem, the aperture blades are misaligned. I did check that the new lens has a different serial number, so it is not the same lens that I returned.

Letting me wait three months for a new lens is bad. But giving me a new lens which has the same problem as the one I returned is simply appalling.

Bokeh comparison @ 14mm and 20mm

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.

However, it is still possible to get a thin DOF with Micro Four Thirds if you use a close focusing distance. I have evaluated the out of focus rendering (bokeh) at close focus using three lenses: The Lumix G 14mm f/2.5 pancake, the Lumix G 20mm f/1.7 pancake and the Lumix G 14-42mm f/3.5-5.6 kit zoom lens.

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.

GH1 and dead pixels

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.

A computer monitor with 1280x1024 pixels has a total of 1280x1024x3 individual dots, one for each primary colour. This makes almost four million individual dots that make up the image you see. Previously, I took a macro closeup picture of a computer monitor to reveal the pattern of red, green and blue dots.

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.

Self portrait on a bicycle

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.

Hacked GH1 vs GH2: Video quality comparison

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.

Another thing we can note, is that the trees lean a bit to the right. This is due to panning the camera, and the rolling shutter. I've evaluated the rolling shutter effects of the two cameras before, and found them to be comparable. Rolling shutter can create artifacts when using both the GH1 and GH2, but for normal use, it is not a real problem.

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.

Poor man's 3D

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.

Pixel RW-221 wireless RF remote control

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.

Conclusion

This product can be bought at a reasonable price from various auction sites. It has a good quality feel, and works in an intuitive way. All in all, it is highly recommended for those who need a remote control.