Thursday, 30 December 2010

AF speed, GH1 vs GH2

I have previously checked the AF speed of the Panasonic GH1, and the Panasonic GH2. However, the tests were done at different times, and with different setup, lightning, etc. Also, the GH1 firmware has been updated in the mean time. So I decided to check both cameras again, under exactly the same conditions.

Again, I set a LEGO figure in the centre of the image frame, and found the time from pressing the shutter release button to the camera taking the image. I turned on the camera just before testing the autofocus, which means that the focus is near infinity when first pressing the shutter release button.

I did the test under two different conditions. The first was in dim light, with a black background: There is artificial lights, and rather dim at around EV5. The distance from the camera to the LEGO figure was about 0.6m.

The second was with daylight coming in through the windows, and white background. The lightning was about EV9.

Here are a couple of examples:



Panasonic GH1, Lumix 20mm, dim lights, black background



Panasonic GH2, Lumix 20mm, dim lights, black background



Panasonic GH1, Lumix 14-140mm @ 140mm, daylight, white background



Panasonic GH2, Lumix 14-140mm @ 140mm, daylight, white background


And these are the timings I found:

LensGH1, dimGH2, dimGH1, daylightGH2, daylight
Lumix G 14mm f/2.5 pancake0.43 seconds0.43 seconds0.37 seconds0.20 seconds
Lumix G 20mm f/1.7 pancake0.57 seconds0.53 seconds0.53 seconds0.40 seconds
Leica Lumix DG 45mm f/2.8 macro1.07 seconds0.93 seconds0.73 seconds0.43 seconds
Lumix G 14-42 @ 14mm0.43 seconds0.33 seconds0.30 seconds0.20 seconds
Lumix G 14-42 @ 42mm0.47 seconds0.40 seconds0.37 seconds0.20 seconds
Lumix G HD 14-140 @ 14mm0.40 seconds0.33 seconds0.27 seconds0.17 seconds
Lumix G HD 14-140 @ 50mm0.53 seconds0.57 seconds0.40 seconds0.23 seconds
Lumix G HD 14-140 @ 140mm0.70 seconds0.53 seconds0.50 seconds0.33 seconds

What we see here, is that the timings are remarkably similar in the tests done with dim lights. The GH2 has a small advantage to the GH1, especially with the fast focusing zoom lenses. But in this test condition, there is little to gain by using the GH2.

On the other hand, when testing the cameras with more light available, the difference is larger. The GH2 really excels in this test condition.

My previous test gave a larger difference between the two cameras. However, the GH1 firmware has been upgraded several times since that test, and so has the lens firmware. It seems that the GH1, with the up to date firmware, is still very capable.

As for the accuracy of the focus, it is very good with both the GH1 and GH2. Both cameras use CDAF (contrast detection autofocus). This means that the image sensor checks the actual image for focus before the camera takes the picture.

In contrast to SLR cameras, which use PDAF (phase detection autofocus). This means that there are separate AF sensors behind the mirror, which check the focus in some spots in the frame. These sensors must be calibrated to the image sensor, a process which is costly and complicated. Users of SLR cameras often worry that the camera/lens combination is back-focusing or front-focusing, i.e., that the AF sensors are noe correctly calibrated. This is something that users of Micro Four Thirds don't need to worry about.

Modern DSLRs can also use CDAF, which is generally refered to as "live view". However, this focus mode is often quite slow on DSRLs, since few lenses are optimized for CDAF. All native Micro Four Thirds lenses, and some Four Thirds lenses, are optimized for CDAF.

Wednesday, 29 December 2010

Yearly sales statistics from Japan

It's time for the yearly sales statistics from Japan (from BCN Ranking). Here's the list of the 20 most sold system camera units, comprising DSLRs and mirrorless interchangeable lens cameras. I have included 2009 and 2008 for reference.


To make the table more readable, I have categorized the cameras into systems. This makes the following table, with slightly different principles going from 2006-2010. However, it still shows some clear trends:


Nikon had a good market penetration with the Nikon D40 back in 2006, however, since that time they have not been able to sustain the market share. These must be depressing statistics for Nikon.

Canon have been successful in the competition against Nikon the last years, however, in 2010 even they have seen a decline in market share. A decline which seems to have gone to the mirrorless cameras: Sony never got their DSRLs into the market as they wanted, but they've seen a much better penetration with the new Sony NEX mirrorless series.

And for the Micro Four Thirds cameras made by Olympus and Panasonic, the growth continues. From the monthly statistics, we can see that the Olympus E-P2 never was a big seller. It's predecessor, the E-P1, is still on the list of the twenty most selling cameras. People appear to prefer the E-PL1 (with built a in flash), or the E-P1 (for a lower price, at the end of it's product cycle).

Pentax are still succeeding well with their strategy of launching feature packed entry models at a reasonable price.

Saturday, 25 December 2010

GH1 vs GH2: AF during video

When the Panasonic GH1 was launched, it was the only consumer system camera to provide continuous autofocus during video recording. Since this time, several competitors have launched their own systems, with the same capabilities. To regain the throne, Panasonic's most recent GH2 model must improve upon the original GH1. How does it fare?

To test this, I made a LEGO contraption which moves a paper sheet back and forth. The paper sheet has a printout of a sharpness test pattern. Here's how it looks:



But filming this and seeing how well the camera AF can keep up, we can compare the performance of the GH1 versus the GH2.

Lumix G HD 14-140mm

I set the camera up with the Lumix G HD 14-140mm superzoom lens at f=100mm. My experience shows that the lens performs best in terms of AF in the shorter focal lengths, so setting it at f=100mm is extra challenging. Both cameras were left in iA (intelligent auto) mode. Both were filming in 25 fps, 1920x1080 pixels

The camera was mounted to a tripod, not entirely perpendicular to the paper. That way, the test pattern can be seen to move a bit sideways, and not only back and forth.

Here are the results:



Panasonic GH1



Panasonic GH2

Based on these videos, it's easy to see straight away that the GH2 can keep up the focus in a better way. However, I wanted to check more thoroughly. So I studied the frames to see which were reasonably in focus.

What I found, was that the GH1 cannot keep up the focus at all. Rather, only the frames in which the paper is close to the initial position are in focus. The rest are out of focus.

The GH2, on the other hand, manages to follow the sheet's motion. The frames in which the paper moves most quickly are out of focus, but the camera regains focus when coming near the end-points, in which the paper sheet moves more slowly.

Based on my simple study, it is clear that the GH2 continuous autofocus is better than that on the GH1.

Lumix G 45-200mm

Using the Lumix G 45-200mm f/4-5.6 lens at 100mm gave the same result:



Panasonic GH1



Panasonic GH2

It looks like the GH1 with the Lumix G 45-200mm f/4-5.6 keeps up the focus a little bit better than with the Lumix G HD 14-140mm. This is consistent with my previous experience, in which I found that the 14-140mm is a bit slow to focus in the longer part of the zoom range, and that the 45-200mm is very fast except in the very longest end.

Leica Lumix DG 45mm macro

I also did the same experiment with the Leica Lumix 45mm f/2.8 macro lens. However, the lens was not able to keep up the focus with either camera. It is clearly not as fast focusing as the Lumix G HD 14-140mm lens.

Thursday, 23 December 2010

Comparison: GH1 and GH2

When I first got the Panasonic GH1, I noted down some improvement areas for the camera. While it was a good camera, there where many areas where I felt it could be improved. Upon getting the GH2, I am happy to note that many the items have been ticked off.


Panasonic GH1 (left) and GH2 (right)

Some of the items I wrote down were very unrealistic, like implementing in body image stabilization. Panasonic have chosen their strategy, to implement image stabilization in some lenses only, not in the camera bodies. So this is not going to happen.

But a lot of other areas have improved. Here are some examples from my list:

  • The control wheel has been moved to the rear side, which I prefer.
  • The built in flash has become taller (as can be seen in the images below), meaning that the premium kit lens Lumix G HD 14-140mm casts a smaller shadow when using the flash.
  • The new camera does feature a simplified focus scale in the display when focusing manually with a Micro Four Thirds lens. This is not an absolute focus scale with measurements, but it tells you if you are moving towards the close or far end of the focus scale, for example.
  • The camera can autofocus with more Four Thirds lenses. For example the Olympus Four Thirds 50mm f/2 1:2 macro. However, the focus is slow for some of these lenses.
  • When using legacy lenses, you can access the magnified focus assist view by pressing the rear control wheel. On the GH1, you needed to press two keys to get this mode: First the left arrow key, followed by the down arrow key.

There are also some development areas that remain. For example, the buffer clearing speed is very slow when recording both JPEG and RAW images.





Physical appearance

The basic shape remains very similar. The shell has been made from a different plastic material with a "crinkle" appearance. While the majority of the GH1 body was covered with a rubber-like covering, the shell of the GH2 is more slippery.

On the other hand, the GH2 gains a more solid rubber grip. Somehow, I find that the rubber-like surface of the GH1 feels safe to operate: The camera is less likely to slip out of your hands. On the other hand, the GH2 has a better grip area for the right hand.

Some people have reported that early versions of the G1 had the rubber surface peeling off. This caused negative publicity for Panasonic, and may be the reason why they have chosen a plastic surface without the rubber coating for the GH2.


On the rear side, we can note some changes. The GH2 (left) has a more pronounced frame around the LCD, which I suppose is good for protection. The red video record button had to be moved to the top-side, since the space it previously occupied is now taken up by the thumb wheel.

A subtle, but good change, is that the display button has become flatter. On the GH1, it was easily pressed by a mistake, and now this is not a problem anymore.


From the side, we can see that the SD card compartment has been moved a bit inwards into the camera. My speculation is that this was needed to fit the extended processing power in the GH2 camera.

This placement makes the card a bit more awkward to extract: There is little space for your finger between the card and the compartment door.


As a consequence of the new SD card placement, perhaps, the battery needs to be slimmer. The GH2 battery (DMW-BLC12, left) is new, which has angered some fans. This means that you can not reuse your extra GH1 battery (DMW-BLB13) for the GH2.

In this view, we also see that the tripod mount has shifted backwards.


In this side view, we see that the new flash is taller, which is very good news. Ideally, the built in flash should be as far from the lens as possible, when extended.


Video quality

The GH1 was marketed as a hybrid stills and video camera, the first in it's class to have continuous AF during video recording. In the mean time, some competitors have launched their systems. So to regain the throne as the best video enabled system camera, the GH2 must excel in video quality.

My experiments so far indicate that the GH2 does indeed provide better video quality. I devised a simple test to compare the GH1 (hacked) with the GH2 in otherwise identical settings.

What I found was that the white balance and saturation of the GH2 is more pleasing, and also that the sharpness of the video is probably a tad bit better. But in my opinion, there was not a dramatic difference.

The GH2 features a much appreciated ETC (Extended Tele Conversion). This is essentially a digital zoom that works during video recording. So your lenses become 2.6 times longer, and you can still record at full HD 1080 resolution.

I've also checked the rolling shutter properties of the two cameras. I found that they were mostly identical in this respect. The GH2 might be slightly better.

Anyway, rolling shutter artifacts is not a huge problem with the GH1 and GH2 cameras. Unless you deliberately generate the artifacts, you're very unlikely to find this being a problem. This is in contrast to the Samsung NX10, which I found had significant rolling shutter artifacts.

Autofocus speed

While I had no problems with the autofocus speed of the GH1, I am still happy to see that they have further improved with the GH2.

I'm especially happy that the autofocus has improved when using the Lumix 20mm f/1.7 pancake lens, which felt a bit sluggish on the GH1. Here is a summary of my AF speed readings.

The GH2 appears to be better at continuous autofocus too, according to my test.

Taller built in flash

As mentioned above, the GH2 has a taller built in flash. In theory, this should be good for several reasons: Keeping the built in flash as far away from the lens as possible is generally a good idea. It makes the lightning more flattering when photographing people.

Also, it is a known fact that the GH1 built in flash casts shadow when using the premium kit lens Lumix G HD 14-140mm. Here's how the shadow looks using GH2 (left), and GH1, both at 14mm and having the lens hood attached.



GH2
GH1

As you can see, the GH2 flash reduces the shadow cast a tiny bit, but the difference is rather subtle. On the other hand, you would probably not use the flash at 14mm focal length and 1 meter distance very often. And increasing either will reduce this problem. So for real life use, this is not that much of an issue.

Mirrorless cameras, like the GH1 and GH2, typically require a pre-flash to measure the intensity of the flash. This takes some more time than with DSLRs, since mirrorless cameras don't have a light sensor. They use the imaging sensor as a light sensor.


Battery life

Compared with most DSLR cameras, the battery life of the GH2 is not very impressive.  This is due to operating in live-view all the time.  DSLR cameras don't need the LCD for viewing during SLR mode, and save power that way.

With freshly charged battery, I found that I could record 144 minutes of video before needing a recharge.  This was with the LCD display on all the time. Using the EVF rather than the LCD probably gives better battery life.

It is possible to buy third party batteries for around US$20, but they give some reduced functionality.

Monday, 20 December 2010

GH1 vs GH2: Rolling shutter evaluation

Rolling shutter is the name of a type of mechanical or electronical shutter mechanism. In this type of shutter, the whole film or sensor is not exposed exactly at once, but rather, a shutter rolls across the frame and exposes it bit for bit. Rolling shutter is also the name of the distortion associated with this shutter implementation.

You can see this distortion for example when panning heavily during video recording. It looks like the scenery is "leaning" towards one side when panning. I tried the Samsung NX10, and immediately noticed that the viewfinder had much more rolling shutter artifacts than the Panasonic G-series.

This shutter implementation also leads to distortion to rotating elements. To test which camera has the most rolling shutter artifacts out of the Panasonic GH1 and GH2, I made a simple LEGO contraption which rotates a propeller at a constant speed. Then I videofilmed this with both cameras, using the Olympus 50mm f/2 lens.

Here are the two video streams:



GH1, ISO 1600, f/2, 1/500 second, 25p, 1080



GH2, ISO 3200, f/2, 1/1000 second, 24p, 1080

To more easily compare the rolling shutter artifacts, I have made similar framegrabs from both:


What we see here, is that the distortion is slightly smaller in the GH2 video stream. The shorter the distance between the two prongs to the left, the more the distortion.

So my conclusion is that the GH2 handles rolling shutter at least as good as the GH1.

For real life usage, rolling shutter is not a problem with GH1 or GH2 video. You can generate these effects by filming a rotating propeller, like I did here. Or by panning heavily. But most types of video footage will not display any noticeable rolling shutter artifacts.

As a side note, the amount of rolling shutter artifacts depend on the speed of the rolling shutter (in a mechanical implementation), or the speed of the sequential image data readout for a digital shutter. It does not depend on the shutter speed itself. Here is an illustration, where you can see three different shutter speeds generating the same amount of rolling shutter artifacts. But the amount of motion blurring is of course different.


Another term widely used is global shutter. This refers to a system in which the exposure values from the sensor are read all at once. Since the values are not read out sequentially, there are no rolling shutter artifacts with a perfect global shutter.

Before launching the GH2, a Panasonic representative was quoted saying that implementing a global shutter in Micro Four Thirds cameras is not coming soon: At the very earliest with the GH3. In retrospect, the the Panasonic GH3 did not introduce global shutter. And now, it looks like the GH4 (aka GH4K) is going to be more about 4K video than global shutter.

Thursday, 16 December 2010

Comparison @ 14mm

There's a number of Micro Four Thirds lenses which include the 14mm focal length. So it's natural to compare their properties at this focal length. I've compared these:

Lumix G 14mm f/2.5 pancake

Lumix G 14-42mm f/3.5-5.6 Mega O.I.S.

Lumix G HD 14-140mm f/4-5.8 Mega O.I.S.

I did the comparison by taking the same photo with all three lenses, at various apertures. The pictures were taken with the Panasonic Lumix GH2 camera on a tripod, at ISO 200. I used the self timer to avoid camera shake during the exposure, and disabled image stabilization. The pictures below were rescaled and sharpened. Here they are:


14mm pancake @ f/2.5


14-42mm @ 14mm f/3.5


14-140mm @ 14mm f/4.0

Field of view

These lenses are specified to 75° field of view at 14mm focal length. We see from the example images that the field of view is very consistent. You will notice some changes in the perspective for close objects. This is due to the physical length of the lenses, which varies, with the pancake obviously being the shortest lens.

A closer examination

To better be able to compare the bokeh and sharpness of the lenses, I have looked at 100% crops from the same area of each image. These images have not been scaled or sharpened. Click for a larger version.



Bokeh

The bokeh (out of focus rendering) is pretty similar for all three lenses. When ranking them, I would put the 14mm pancake first, then the 14-42mm zoom, and finally the 14-140mm superzoom. But the differences are small, indeed.

Note that in this case, I am focusing on near infinity, and looking at the bokeh of near objects. It could be that the nature of the bokeh of far objects when focusing on a near object is different. So more tests are certainly needed to make a perfect conclusion.

If you are interested in getting nice bokeh, these are not the right lenses to choose, anyway. Longer lenses are better, if you are interested in keeping some parts of the image out of focus. I would recommend the Lumix G 45-200mm f/4-5.6 value tele zoom for this application. An even better, and more expensive choice, is the Panasonic Leica Lumix DG Macro-Elmarit 45mm f/2.8 1:1 Macro. (It seems that the longer the name, the higher the price.)

Flare

When it comes to flare handling, though, it seems that the Lumix G 14mm f/2.5 pancake handles it the best. This is probably due to it's simpler optical design: It only comprises six lens elements. Generally, the fewer lens elements, the better it handles flare. Of course, there may very well be exceptions to this general rule.

Sharpness

To my surprise, I note that the basic kit lens Lumix G 14-42mm f/3.5-5.6 Mega O.I.S. is sharper than the very expensive Lumix G HD 14-140mm f/4-5.8 Mega O.I.S. at f/4, and even at f/3.5. The superzoom lens does sharpen up a lot when stopped down to f/5.6, though.

I'm thinking the tripod might have been accidentally shaked during the 14-140mm f/4 exposure. I should revert to this later to check if that might explain the unexpected softness.  On the other hand, it is a well known fact that the 14-140mm zoom is a bit dull in the wide and long ends.

The Lumix G 14mm f/2.5 pancake lens is quite sharp at max aperture, and appears to reach it's sharpest around f/5.6, which is quite common for this type of lens.

Alternative views

Here are some alternative crops from the same images. The are from the middle, right border of the image.


There is some passing traffic which makes the lightning a bit different. This is unfortunate, but no big problem in the comparison. Also, some wind is affecting the tree.

Here's another set of 100% views, from the left hand border of the image:


The conclusions are pretty much the same as from the other images. We can see that the Lumix G 14mm f/2.5 pancake lens is somewhat less sharp at f/2.5, compared with the centre. But it sharpens up when stopping down to f/2.8. Overall, I am pretty happy with the sharpness of the pancake lens.

Vignetting

In the last image, we can also note that the borders are a bit darker due to vignetting. This is an issue mostly when the lens is wide open. When closing down about one stop, the problem goes away.

Conclusion

The Lumix G 14mm f/2.5 pancake appears to be an adequate lens in all these tests. It has some vignetting wide open, and it is not tack sharp wide open. The bokeh could conceivably have been better. But all in all, it is a good lens.

You should probably not buy the 14mm pancake lens for the ultimate optical performance, but rather for the compact size, stealthy appearance, and fast autofocus. Add a bit of cuteness factor, and it becomes a tempting buy. Here is another test of the optical qualities of the Lumix 14mm pancake lens.

The Lumix G 14-42mm f/3.5-5.6 Mega O.I.S. appears to be a competent lens. While this lens has received a somewhat poor welcome by fans online, I find it to be good. It also has consistently fast autofocus.

People who buy this lens in a camera kit, and are eager to unload it in an online auction should consider to think twice. While it remains a basic kit lens, it can be appreciated for the compact size, lightness, and adequate optical performance. There can be many cases when you'll want to use a small, light kit zoom lens.

Our most expensive lens, the Lumix G HD 14-140mm f/4-5.8 Mega O.I.S., disappoints in this test. While I am doubting the results at 14mm f/4 a bit, it is a well known fact that this lens is a bit unsharp in the wide and long ends of the zoom. You shouldn't toss it based on this test, but keep in mind that it excels in terms of sharpness in the focal range between the extreme wide and longest end.

My test subject here was far from optimal. However, with the dark and cold winter, I was a bit out of inspiration, and didn't want to lug the gear around too far in -10°C.

Wednesday, 15 December 2010

Video quality, hacked GH1 compared with GH2

I've tried to test the GH1 (hacked) and the GH2 under the same conditions. To make sure the conditions were the same in both tests, I made a rotating platform using Technic LEGO, and left it under artificial lights. To better be able to judge the quality, I put a sock on the platform. The sock has some texture, which will come in handy in the comparisons.

The lens used was the Panasonic Leica 45mm f/2.8 lens. The focus was put on the centre of the image, and I used f/6.3, ISO 400 for some depth of field.

Both videos are filmed in 1920x1080 pixel resolution. The GH1 is hacked to a maximum of 44Mbit max bandwidth, while the GH2 has the native firmware. The GH1 video stream is 25p, the GH2 is 24p. I used the new Cinema 24p mode on the GH2.

The GH1 stream is 11 seconds, 38.430.720 bytes, 3.5MB/s.

The GH2 stream is 10 seconds, 27.998.208 bytes, 2.8MB/s.

So there is more information in the hacked GH1 stream. However, this does not necessarily mean that it's better.

Here's the GH1 (hacked):



And the GH2:



It's not easy to make an objective comparison based on these YouTube videos. So to be more fair, I have made frame grabs from the video streams.

GH1 (hacked):


GH2:


To make the comparison even better, here are 100% views of two similar framegrabs (click for a larger version):


Conclusion

First of all, it is easy to conclude that the colour balance is different. I have the same saturation settings in both cameras (+1), and the lightning was the same. So the difference must be due to different implementation of auto white balance. Overall, I feel that the GH2 colours look more natural.  It's not strange that the cameras struggle with the colour balance here.  After all, there is artificial light, and the subject colours are rather strange.

When it comes to the sharpness, I think the conclusion is that the GH2 has better image quality. Even though the bandwidth is a bit smaller than in the hacked GH1.

I have also made a comparison of the GH1 video quality before and after the hack, in which case I found that the video quality was slightly better after the hack.

Sunday, 12 December 2010

GH2 touch screen AF (superzoom example)

I've previously tested the touch screen AF of the GH2, using the 45mm macro lens.

Here's another example using the touch screen AF with the Lumix G HD 14-140mm superzoom lens. The lens was set to 100mm focal length.



As you can see, the response is still somewhat slow, but the actual focus action of the lens is faster than when using the Lumix Leica 45mm f/2.8 macro lens.

I'm using the A mode on the mode dial. Using the iA mode typically gives me the focus tracking mode, in which the response time from touching the screen until the focus changes is a bit shorter.

When using the shutter button to trigger focus, the focus is very responsive, just like in my study of the GH2 autofocus speed.

When recording videos, you can change the focus areas using the touch screen as well. The response and speed is similar to this example.

I have also made an analysis of the focus speed of the GH2 for a number of lenses, and compared with GH1 for some of them.

Saturday, 11 December 2010

GH2 touch screen AF (macro example)

One of the new features of the G2/GH2, is touch screen LCD. Some fans have been negative about this feature, since they are afraid of losing the hard buttons on the camera body. It turns out that the touch LCD is an additional feature, and that it does not replace any hard button functions. So those who dislike a touch screen can ignore it, without losing any vital functionality.

One application where the touch screen makes some sense, is macro photo. It is rather quick to move the focus point around in the frame. Here is an example usage, with the Panasonic Leica 45mm f/2.8 lens:



You can doubleclick on the video to be able to view it in other sizes.

As you see, the response is not very quick. It takes a moment from changing the focus point until the camera actually starts changing the focus.

I'm using the A mode on the mode dial. Using the iA mode typically gives me the focus tracking mode, in which the response from touching until the focus changes is a bit faster.  So if you want the focus response to be quicker, set the dial to iA.

In the video, I am sliding my finger over the screen now and then.  This is not necessary. You can just point where you want the focus point.  My sliding finger action is probably something I've learned from using an Iphone.

This can also be done during video recording. The response speed is the same, as far as I can tell, during video recording.

Of course, the PL45 lens is not the quickest around in terms of autofocus. Using a quicker lens will make the response quicker as well.

I have also made an analysis of the focus speed of the GH2 for a number of lenses, and compared with GH1 for some of them.

Thursday, 9 December 2010

Panasonic GH2 autofocus speed

Update: Since this test, I have compared the GH1 and GH2 head to head under exactly the same conditions.

I have tested the autofocus speed for the Panasonic Lumix GH2 with various lenses. The test was done by turning on the camera (which leaves the lens at near infinity focus), and then pressing the shutter to see how long time it takes to reach focus. This was filmed using a GH1, and I played back the video in a video editing software, to read out the timings.

There is fairly dull indoor lightning. The lightning corresponds to around EV 6, the same as in my previous test of the GH1. A LEGO figures is placed in the middle of the camera frame, at around 45cm distance. The focus mode used is centre spot.

Here is an example test. In this test, I have the Olympus 9-18mm f/4-5.6 Four Thirds lens mounted to the camera, using an adapter. (Not to be mistaken with the Micro Four Thirds version of the lens.)



This combination gives a rather slow autofocus.

Another example using the Lumix G 14mm f/2.5 pancake:



As you see, the Lumix 14mm lens focuses very fast.

Another example, using the Leica Lumix DG 45mm macro:



This lens does not focus as fast as some of the other lenses, but it's still fair to say that the focus is not slow.

Summary

Here are the timings. I have included a column with the similar autofocus times for the GH1. You should note that the GH1 timings were done with early camera and lens firmware. Later firmware have improved the AF speed.

LensFocus time GH1Focus time GH2
Lumix G 8mm fisheyeNot tested0.24 seconds
Lumix G 14mmNot tested0.20 seconds
Lumix G 20mm1.23 seconds0.44 seconds
Leica Lumix DG 45mm macroNot tested0.60 seconds
Lumix G 14-42 @ 14mmNot tested0.28 seconds
Lumix G 14-42 @ 25mmNot tested0.20 seconds
Lumix G 14-42 @ 42mmNot tested0.44 seconds
Lumix G HD 14-140 @ 18mm0.53 seconds0.16 seconds
Lumix G HD 14-140 @ 50mm0.40 seconds0.40 seconds
Lumix G HD 14-140 @ 140mm0.68 secondsNot tested
Lumix G 45-200 @ 45mm0.33 secondsNot tested
Lumix G 45-200 @ 100mm0.36 secondsNot tested
Lumix G 45-200 @ 200mm0.87 secondsNot tested
Olympus ZD 4/3 9-18 @ 9mm2.90 seconds1.44 seconds
Olympus ZD 4/3 9-18 @ 18mm1.50 seconds1.36 seconds
Olympus ZD 4/3 50mm f/2No AF4.76 seconds

Conclusions

What we can see, is that the GH2 autofocus speed is very good. The Four Thirds lenses used on adapter are still slow, but they behave better. The Olympus 50mm f/2 macro lens can actually autofocus on the GH2, but the speed is very, very slow. It could be used for stationary objects, but for photographing people, the AF is more or less useless.

The Panasonic Lumix GH1, and the whole first generation of Panasonic G cameras, could not autofocus with the Olympus Four Thirds 50mm f/2 macro lens. This also applies to a host of other Four Thirds lenses that are not optimized for CDAF. The newer GH2 can autofocus with most Four Thirds lenses. However, the focus can be rather slow, as we have seen in this example.

Even the Four Thirds Olympus 9-18mm f/4-5.6 wide angle zoom lens, a fairly recent CDAF optimized lens, has an annoyingly slow autofocus. The AF is usable, but not as fast as we have become used to.

I am also rather happy that the autofocus speed for the Lumix 20mm f/1.7 pancake lens has improved a lot with the GH2. After all, this is a very good lens, and I find the AF speed to be important when photographing people.

As expected, the Lumix G HD 14-140mm superzoom lens remains very fast in terms of AF. It seems that the close focusing range differs for various focal lengths. The close focus range is specified at 50cm, however, it can focus a bit closer in the wide end of the zoom range. I was not able to test the lens in the longer range this time, since it would not reach focus there at 45cm distance.

The new kit zoom Lumix G 14-42mm is also a very competent lens when it comes to focus speed. I think this was to be expected, after all, it is a brand new kit lens, and focus speed is one of the important factors when people buy camera kits.

Sunday, 5 December 2010

Lens hoods

Frequent readers of my blog will know that I like to tinker with lens hoods. Here is a summary of some of the lens hood solutions I like.

Panasonic Lumix G 20mm f/1.7 pancake

This lens does not come with a hood at all. While a hood is probably not much needed from a stray light perspective, I still like to put a hood on my lenses for protection against objects accidentally touching the front lens element.

My favourite solution is to put a 46mm to 37mm step down ring as hood. This gives some basic protection of the front lens element, while keeping the overall package compact.


I've checked that there is no extra vignetting caused by the step-down ring.

In addition, you'll need a 37mm front lens cap. Both can be gotten from various auction sites for about US$10 in total.




This lens features a traditional focus mechanism, in which the whole lens assembly moves back and forth. Adding extra weight to this assembly is generally not a good idea. However, the step-down ring doesn't add that much weight. Less than a glass filter would, anyway.

Another solution is to get a 46mm metal screw in hood designed for Leica Summicron:


While this hood looks stylish, I think it adds too much bulk. Besides, you might not be able to fit the front lens cap inside it.



Panasonic Leica Lumix DG 45mm f/2.8 1:1 macro

This lens does come with a hood, however, I am sad to say that I find the hood completely hideous:


This hood does look stylish, and reminds me of the older Leica hoods. However, it is much too wide, and could have been used for a wide angle lens. But this lens is a short tele. So the hood does not do a good job of keeping stray light out.

I prefer a hood that is a narrow as possible, while still not inducing any extra vignetting. I found the solution I like by adding three extra elements to the front lens thread: First a 46mm stand off ring (glassless filter), then a 46mm-37mm step-down ring, and finally, a 37mm-28mm step-down ring:


I was almost a bit surprised when I verified that this combination does not add any extra vignetting. But the front lens element of the 45mm macro has a rather narrow diameter, so I suppose it makes sense.

This "hood" does not add any extra diameter to the lens, which is good. In addition, you'll need a 28mm front lens cap. Such a cap is pretty inexpensive.





Olympus M.Zuiko Digital 45mm f/1.8

In a move which has annoyed quite some fans, this lens is not sold with a hood included. There is a hood you can buy from Olympus, which fits in to the bayonet mount. However, it is quite expensive.

I bought a collapsible rubber hood for screwing into the 37mm front threads. It works great:


This rubber hood cost me US$13, including shipment from China.



Panasonic Lumix G 14mm f/2.5 pancake

Just like the 20mm pancake, this lens does not come with a hood. Again, I've used the same solution as with the 20mm pancake lens: A 46mm to 37mm step down ring as hood:


In this case, I had bought a grey ring by a mistake, so I had to paint it black with enamel paint. No big deal.




This lens features internal focusing, so I am not afraid of putting some extra stuff onto the front lens thread.

Panasonic Lumix G 45-200mm f/4-5.6 Mega O.I.S.

This lens does come with a hood, and I think the hood is very well designed:


The only problem I can see, is that it is awkward to insert and remove the front lens cap.

I still changed this hood, since it was a tad bit too long for my camera bag. I got a 52mm screw in metal hood:


This alternative hood is probably not as good for protection, but is is more practical to use, and it's easier to add the front lens cap after use.



Other lenses

The kit zoom lenses generally have well designed hoods, and I see no reason to replace them.

Wednesday, 1 December 2010

Testing the effect of the GH1 hack

For a while now, it has been a well known fact that the Panasonic Lumix GH1 firmware can be adjusted to yield higher video bitrate, among other things. This is referred to as using "the hack", or "hacking" the GH1. Similar adjustments can also be done to the GF1 and G2 cameras.

I wanted to test the effect of the hacked GH1. Is it possible to measure the improvement of the video after installing the hack? I know many people have praised the quality of the hacked GH1 video before, but I wanted to make sure this test has exactly the same moving subject and lightning before and after installing the new firmware.

Test setup

Here is my test setup:


The camera is on a tripod, with the Leica Lumix 45mm f/2.8 macro lens. The camera is set to f/5, 1/60s, ISO400. The LEGO figure is on a platform that rotates at a constant speed.

I recorded one video file before installing the hack, and one after. When adjusting the firmware, I upped the max bandwidth from 16,000,000 to 50,000,000. Both videos were recorded at Full HD, 1920x1080 pixels. This can only be done using the AVCHD format. My camera is the PAL version, meaning that I get a framerate of 25fps.

The first video is 11s, and 20,754,432 bytes, 1.89MB/s. The second video is also 11s, and 31,395,840 bytes, 2.85MB/s, 50% higher than before the hack. So already here there is an indication that the hacked video contains a higher bandwidth.

Video examples

Here are the videos. You can double-click on the video to get to the YouTube page, where you can see them in higher resolution, up to 1080p.

Before the hack:



After the hack:



Of course, just watching the videos on YouTube isn't enough to judge the quality. For an extra test, I have made some framegrabs from the videos, to compare the quality.

First, two full size framegrabs from the video.

Before:


And after:


It's still difficult to compare the quality of the images. Here are 100% crops from the 1920x1080 framegrabs. I chose four consecutive frames from each video stream. Click on the image for a larger version.


Conclusion

Based on these screenshots, I believe it looks like the there is some more clarity and sharpness in the hacked video stream. Also, the colours are more washed out without the hack. The hacked video stream is better. But from my experiment, I don't see a dramatic difference.

Other effects

After recording the second video, I was not able to playback the videos any more. Just showing the thumbnail in the viewer was enough to freeze the camera. To reset it, I needed to remove the battery. Just flipping the on/off switch was not enough. This is, of course, quite annoying.