GH1: Use RAW and gain 1% megapixels

The Panasonic Lumix GH1 has a 14 megapixel multi aspect sensor, with around 12 megapixel output at three different aspect ratios: 4:3, 3:2 and 16:9.

At 4:3, the JPEG image is 4000x3000, which is easily calculated to 12 million pixels. The corresponding RAW file, on the other hand, yields 4018x3016 pixels, or a total of 12.118.288 pixels, which is 1% more megapixels than the JPEG output.

The same goes for the other aspect ratios. At 16:9, the JPEG image is 4352x2448, or 10.65 megapixels. The RAW file has a 4396x2464 resolution, 10.83 megapixels, a difference of 1.7%.

Of course, an increase of 1-2% of the resolution is hardly significant, and no real reason to use RAW alone. But there could be situations where you need a little bit extra details around the edge, and then looking at the RAW file could help you.

Here is an example exposure in two versions, developed from RAW (top) and JPEG (bottom):

From RAW, 4396x2464

From JPG, 4352x2448

It is hardly possible to notice any differences between the two images, when shown scaled down like this. However, when looking at a 100% crop from the right hand border, the differences are obvious:

We are losing a little bit of details in the borders when using JPEG, as opposed to RAW.

Appendix

The lens used here was the Four Thirds Olympus 9-18mm f/4-5.6, with the Panasonic DMW-MA1 adapter. The lens was used at 9mm, f/4, ISO 100. In the image above, you can see a typical example of chromatic aberration (CA). This is noticeable as the purple and green fringing along areas of high contrast, where black and white paint meet.

I have been using UFRaw to convert RAW files in Linux.

Panasonic GH1 exposure, nightscenes

I have noted that the Panasonic GH1 consistently gives too dark exposures in night scenes, or more generally, in scenes with high contrast, large difference between the light and dark parts of the image.

Here is an example scene, shot with two different cameras. Panasonic GH1 top, and Pentax K10D bottom.

Panasonic GH1

Pentax K10D

Both cameras were set in "P" mode, auto white balance, and multi segment exposure metering. The field of view was 200mm (film camera equivalent), with aperture f/6.7, ISO 400. The JPEG images were used straight from the camera, with rescaling and a little bit of sharpening.

As you can see straight away, the Pentax exposure is much more usable, even if the white balance could have been better. But in terms of white balance, this is a very trick situation anyway, with artificial lights.

Let's compare the JPEG histograms, taken from the Gimp image processing software:

Here it is very apparent that the Pentax has a more useful exposure. The Panasonic exposure appears to be designed to avoid blown highlights, while the Pentax exposure puts more weight on preserving details in the shadows.

Highlight details

Let's see how the highlights compare. Here are 100% crop from the same area in both pictures:

Panasonic GH1

Pentax K10D

As is apparent, Panasonic exposes less, and hence is able to preserve more details in the highlights. However, to achieve this, a lot of detail in the darker parts of the picture, which makes up the most of the area, is lost.

Appendix

The lenses used were the Panasonic Lumix G HD 14-140mm f/4-5.8 @ 100mm, and the Pentax DA* 50-135mm f/2.8 @ 135mm. The camera was on tripod during both exposures. The exposures were around a couple of seconds, with image stabilization turned off. You can see that the Panasonic lens is much sharper, even if it is less stopped down. This is quite a feat for a 10x zoom. On the other hand, the Pentax lens is a faster lens, which implies other compromises in the design.

Four Thirds lens compatibility

Panasonic Lumix Micro Four Thirds (MFT) cameras can use all Four Thirds (FT) lenses, provided that you use an adapter. You can use either the Panasonic DMW-MA1, or Olympus MMF1/MMF2 adapters.

However, you should note that not all FT lenses will autofocus on Panasonic MFT cameras. Only fairly recent lens designs that are prepared for contrast detection auto focus (CDAF), will work. The compatible FT lenses are

• Olympus Zuiko 25mm f/2.8 Pancake
  
• Olympus Zuiko 9-18mm f/4-5.6
  
• Olympus Zuiko 14-54mm f/2.8-3.5 II
  
• Olympus Zuiko 14-42mm f/3.5-5.6
  
• Olympus Zuiko 40-150mm f/4-5.6
  
• Olympus Zuiko 70-300mm f/4-5.6
  
• Panasonic Leica D Summilux 25mm f/1.4 Asph
  
• Panasonic Leica D Vario-Elmar 14-50mm f/3.8-5.6 Asph Mega O.I.S.
  
• Panasonic Leica D Vario-Elmar 14-150mm f/3.5-5.6 Asph Mega O.I.S.

These lenses will autofocus on Panasonic Lumix MFT cameras, like G1, GH1 and GF1.

Newer Panasonic cameras like GH2, G2 and G10 feature some improved autofocus functionality using some FT lenses. For example, the GH2 can autofocus using the Olympus 50mm Four Thirds lens, but the focus is very slow. The Panasonic G1, GH1 and GF1 will not autofocus this lens at all.

All Olympus MFT cameras can autofocus with all FT lenses, so Olympus camera users can ignore this list. This also goes for Panasonic FT lenses used on Olympus MFT cameras. The autofocus can be very slow with some FT lenses, though.

For those combinations of lenses and cameras where autofocus works, you will still experience slow autofocus with FT lenses on both Panasonic and Olympus MFT cameras. I have made a comparison of autofocus speeds using some MFT and FT lenses on the Panasonic GH1. Also, a similar comparison for the Panasonic GH2.

Even if autofocus does not work on some camera/lens combinations, other functions like aperture control will still work. And using manual focus is not that difficult. Here is an illustration of using manual focus with Olympus 50mm f/2 macro on Panasonic Lumix GH1.

Panasonic Lumix GH1

When the Panasonic Lumix G1 was launched in the autumn 2008, it was the first camera in the Micro Four Thirds system. While it was an innovative camera, it had one feature missing: Video recording. The lack of video was seen as very strange, as the sensor was obviously capable of sending live video feed to the display.

It was not surprising that when the second Panasonic Micro Four Thirds camera was launched in the spring 2009, it did indeed feature video recording. One year on, it is still the only consumer video capable camera with exchangeable lenses, that also feature continuous autofocus during filming, and a tiltable display, features that I would say are essential.

During most of the camera life time, it was only sold as a kit with the superzoom lens Lumix G HD 14-140mm.

Improvement potential

There are a number of good GH1 reviews out there, and there is not much point in making another one. Let me mention a few features that I would have liked to see on this camera, though. While it is a very good camera, there are also some areas where it could have been further improved.

I think that the focus selector is awkwardly placed, on the top left side. This selector is usually placed on the front, next to the lens mount, where it is easier to operate with the left hand.

Generally, I prefer a thumb click wheel to a finger wheel. Having both is of course the best, but having to choose one, I would choose the thumb wheel. The GF1 has got a thumb click wheel.

The video recording is well integrated into the picture taking functions. However, there are some inconsistencies. For example, leaving the camera in AF Single mode will make it do continuous autofocus during filming. There is no mode that will autofocus when initiating filming, but not during filming. Also, the P, A, S, M-modes do not apply when filming. Rather, you need to select a special "Creative movie mode", and then go into a deep menu to choose from the P, A, S and M alternatives. Wouldn't it be easier to just use the mode dial for this selection for video recording as well? A final drawback is that it is not possible to take still images while filming.

Some image processing features could have been added. For example in-camera RAW conversion, and the ability to delete only the RAW image, or alternatively, only the JPEG image. As the camera works now, you can choose to delete a picture all together, but not only one version of it.

The hood will block the built in flash in most cases, with the exception of extreme tele. Even without the hood, the kit lens will block the flash in a wide range of wide angle to normal focal lengths.

There is no supplied software that does video editing with the AVCHD format. For a premium video camera kit, this is rather disappointing.

The camera is not weather protected, as one would expect from a camera in this price range.

It does not feature any infra red receivers, and hence, there are no simple remote controls available. Some third party remotes can be used.

When focusing manually, an enlarged view comes up, to make precise focusing possible. To go back to the full view, you can tap the shutter release button. However, it would be good to have a dedicated button to bring up the enlarged view. This would be useful if you want to check the focus without turning the focusing ring. Or when using a legacy lens on an adapter. On the other hand, the enlarged view is available through pressing two buttons in a sequence, so this is not a big issue.

Most lenses for this camera do not have a focus scale. The exceptions are some Four Thirds lenses that can be attached through an adapter. Furthermore, there is no focus distance indication on the camera. You will see that premium Panasonic compact cameras, for example the LX3, do feature focus distance information in the LCD display. The fact that Micro Four Thirds cameras all lack this feature leads me to think that the focus distance information is probably never communicated from the lens to the camera at all.

When using autofocus, the lack of a focus distance indicator is no big deal. However, there are some times when you want to prefocus at a certain distance, and shoot quickly in manual focus mode for speed and/or stealth. In these cases, it is a bit awkward to know at what distance the lens is focused.

While the Olympus Micro Four Thirds cameras can autofocus with Four Thirds DSLR lenses on an adapter, the Panasonic cameras can only do this with a select few. One example is the Olympus 50mm f/2 macro lens. One could guess that this is not due to technical limitations of the Panasonic equipment, but rather due to an agreement between Panasonic and Olympus. Also, when using manual focus, there is no focus confirmation in the viewfinder. This would have been useful, especially for legacy lenses used on adapters.

When using the front wheel to change aperture, turning the click wheel one way yields different outcomes in P and M mode, respectively. This inconsistency of the aperture input is annoying and unnecessary.

In P mode, you can not adjust the aperture using the index finger wheel until the camera has achieved focus. So to adjust the aperture, you first need to half press the shutter to get focus, and then operate the click wheel.