Panasonic Lumix DMC-GH1 Features
When announced in March 2009, [5] the Panasonic Lumix DMC-GH1 was marketed as a new class of "Creative HD Hybrid" camera, and as Panasonic's top-of-the-line Micro Four Thirds (MFT) system camera. The GH1 appeared to be the first fully compliant camera with the MFT system standard, which includes High Definition (HD) video capability. The hybrid GH1 was designed to not only to take still photos, but full HD video, including manual controls over many video functions.
The resulting GH1 camera was a smaller and lighter interchangeable lens camera when compared with traditional Digital Single Lens Reflex (DSLR)s. Like a DSLR, the GH1 design follows the interchangeable lens DSLR form and function instead of the more traditional handheld consumer video camcorder form and function. Unlike the DSLR, the GH1, eliminated the bulky mirror box and pentaprism assembly in favour of a high resolution electronic viewfinder (EVF), allowing smaller, lighter overall body size and the use of new, smaller and lighter weight lens designs.
At first glance, the GH1 appeared to be just a video capable version of the world's first MFT system camera, the Panasonic Lumix DMC-G1 mirrorless interchangeable lens camera, first introduced in September 2008 [6] In fact, there were many distinguishing features that made the GH1 a unique, and perhaps even a ground breaking product. Some of these features, as well as some that appeared on the DMC-G1 are discussed below including a new multi-aspect image ratio sensor, full AVCHD HD video capability, stereo sound recording, dual CPU image processing, and a super zoom lens optimized for video.
Multi-Aspect Ratio Sensor
Panasonic first pioneered the concept of a multi-aspect ratio image sensor in its high-end compact camera, the 2008 Panasonic Lumix DMC-LX3 which used a much smaller 1/1.63" CCD technology sensor. [7]
Building on the multi-aspect ratio sensor concept, the HD video capable GH1 was designed around a much larger four thirds sized sensor (about four times more area); a unique 14.0 megapixel (12.1 megapixel effective) Live MOS sensor. [8] The 14 megapixel multi-aspect image ratio GH1 sensor was designed to cover a slightly larger image circle than the native 4:3 image aspect ratio of its 12.1 megapixel cousin in the G1. This means that the GH1 14 megapixel sensor was capable of recording images in user selectable, native aspect ratios of 4:3, 3:2 and 16:9 with no cropping, and more importantly, the same angle of view and maximization of pixel count in any particular format.
Most other digital cameras achieve different image aspect ratios by cropping the image from the native sensor format. For example, most digital cameras with native 4:3 image aspect ratio sensors crop the native image on the top and the bottom to achieve either 3:2 or 16:9 images. On the other hand, most DSLRs crop their 3:2 native image aspect ratio on the top and the bottom to achieve 16:9, or in some cases, crop the 3:2 native image on either side to achieve 4:3 images.
In fact, the GH1 sensor is never used to its full capacity for 14 megapixels, but for any of the three formats, as much of the sensor is used as possible, and more importantly, each image has the same point of view. For example, when cropping images from a native format, such as a 4:3 image, the point of view changes slightly, and a lot of pixels are lost, close to 25% when cropping a 16:9 image out of a 4:3 native format image. The multi-aspect ratio sensor cuts down on the loss of pixels so the pixel count for each aspect ratio is as close to 12 megapixels as possible. The multi-aspect ratio also allows more usable lens image depending on the format. For example, in a native 4:3 format, the image width is 4000 pixels, but in a native 16:9 format, the image width is 4352 pixels or about 8% wider. With a multi-aspect imager, the net effect is that any given lens has a slightly wider field of view in either native 3:2 or 16:9 when compared to the native 4:3 image format, as demonstrated by the table below.
GH1 Four Thirds Multi-Aspect vs Single-Aspect Ratio Pixel Count
| Multi-Aspect | Width | Height | Area | Single-Aspect | Width | Height | Area | Single-Aspect* | Width | Height | Area |
|---|
| 4:3 | 4000 | 3000 | 12000000 | 4:3 | 4000 | 3000 | 12000000 | 4:3 | 4608 | 3456 | 15925248 |
|---|
| 3:2 | 4128 | 2752 | 11360256 | 3:2 | 4000 | 2672 | 10688000 | 3:2 | 4608 | 3072 | 14155776 |
|---|
| 16:9 | 4352 | 2448 | 10653696 | 16:9 | 4000 | 2248 | 8992000 | 16:9 | 4608 | 2592 | 11943936 |
|---|
| 1:1 | 2992 | 2992 | 8952064 | 1:1 | 2992 | 2992 | 8952064 | 1:1 | 3456 | 3456 | 11943936 |
|---|
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The multi-aspect sensor is also capable of producing 1:1 format images, but this is a cropped image from the 4:3 format.
- ) Olympus OMD E-M5 with 16 megapixels, which in 16:9 format has only 12.1% more pixels compared to the GH1. [9]
True HD Video AVCHD Recording
The GH1 was designed from the ground up to be capable of AVCHD recording in true HD 1080p at 24 frame/s or 720p at 60 frame/s high-definition videos with continuous autofocus (AF) and Dolby Digital stereo sound recording. The GH1 was also the first consumer-priced interchangeable lens camera to also offer continuous autofocus capability while shooting HD video.
Notably, since the introduction of the GH1, every other MFT system compliant camera, whether made by Olympus or Panasonic, has been capable of some type of AVCHD HD video. However, only the GH1 and the successor GH2 have provided the wide range of manual control over HD video recording, garnering the attention of amateur film makers worldwide.
AVCHD is a file based (non-magnetic tape) format for recording and playback of HD video, jointly developed by Sony and Panasonic in 2006 [10] for HD recording. All still or video/sound recording is to a SD or SDHC memory card. The user is also able to manually select shutter speed and aperture openings for more creative control over HD video recording. [11] Dolby Digital stereo sound is recorded via a stereo microphone, with a wind blocking feature to reduce background wind noise, built into the camera. More capable, optional external stereo microphones may also be fitted to the camera. [11]
While giving its best performance while recording in AVCHD, the GH1 can also record in more popular MPEG formats at a maximum resolution of 720p at 30 frame/s.
In the United States, the HD video recording length is limited to the capacity of the memory card (or the battery life, unless the AC power adapter is used). File sizes are no larger than 4 GB due to the SDHC file allocation table limits, but the video will be seamless between files. In Europe, however, the HD video recording length is limited to 30 minutes, due to EU regulatory and tax reasons. [12]
Dual CPU Engine
HD video is data intensive, and Panasonic designed the GH1 around a dual CPU image processing system named the "Venus Engine HD". [11] This dual CPU speeds up HD image processing and offers a number of other advantages, including improved image noise reduction performance, ability to display a live view direct from the sensor for either the fully articulated LCD display on the camera back or the high resolution electronic view finder, a very fast contrast detect auto focus system, and even the ability to output both images and sound via HDMI directly from the camera. [11]
At the time of introduction, the dual processor Venus Engine HD also allowed faster contrast detect autofocus ability at the time, in addition to the implementation of a live view electronic viewfinder with DSLR like functionality, but without the penalty of a complex and bulky mirror box and pentaprism. [8] Several automatic focus modes are enhanced by the dual processor feature, 23 area focus, user-selectable single point focusing, face recognition focus, face detection focus, and automatic focus tracking.
In addition, the dual processor aids in the processor intensive AVCHD video processing.
Contrast Detect Auto Focus with Face Recognition and Detection
Traditional digital single-lens reflex cameras (DSLRs), typified by Canon EOS or Nikon FX or DX offerings use Phase Detect Auto Focus (PDAF) systems. PDAF are typically very fast and responsive systems. When used in Live view mode, especially for video, traditional DSLR's must rely on direct output from the main image sensor in order to autofocus. Relying strictly on the sensor output to autofocus is called Contrast Detect Auto Focus(CDAF). CDAF as implemented in contemporary, traditional DSLR's was so slow as to be almost unusable for all but non-moving objects. [8]
The GH1 lacks a separate PDAF sensor and relies solely on CDAF techniques to autofocus. Designed from ground up as a live view, CDAF camera, and not as an "add on" auto focus system for a primarily PDAF centric camera, the GH1 CDAF system breaks new ground for an interchangeable lens camera. In combination with other features, including a 23 area AF, user selectable single AF point anywhere in the frame, subject tracking AF and facial recognition AF, the dual CPU equipped GH1 offered the fastest and most comprehensive CDAF system available at the time in a consumer camera, on par in most performance areas with similar entry level to mid-level priced contemporary DSLRs. [13]
HD video mode also uses this purpose-designed contrast-detect AF system, making the GH1 the only DSLR styled camera at the time available to offer continuous autofocusing while shooting video.
Newly introduced for Panasonic MFT cameras was "Face Recognition", a facial recognition technology. The GH1 implementation of Face Recognition was an improvement of the concept first introduced in 2007 on the high end Panasonic Lumix DMC-L10 Four Thirds (not Micro Four Thirds) DSLR camera. [14] [15] The GH1 allows the user to memorize two different faces for easier prioritization. For example, if a child's face is set into memory, and the photo has many faces in it, the GH1 will attempt to focus on the memorized face.
Face Detection (as opposed to Face Recognition) is a technology used in a wide variety of cameras. When not using a memorized face, the camera will automatically prioritize focus on a face-like shape that the camera judges could be the main subject of the photo, attempting to further set the focus point, when possible at the eyes, in both still and video recording modes.
High Resolution Electronic Viewfinder
The GH1 uses a high resolution (1.44 million dots) electronic viewfinder (EVF), [8] a sophisticated projection system to achieve a clearer, smoother display than that of compact camera EVFs. The high resolution electronic viewfinder uses a technology known as LCOS, the same technology used in Panasonic's professional high end video cameras, and is supposed to be capable of much higher resolution than either LCD or plasma display technologies. As implemented in the GH1, the effect is 60 frame/s full-time live view with no visible pixels for an image as large or larger, and brighter than competing optical viewfinders using a mirror box and pentaprism than most prosumer DSLR's. [8]
The EVF has a high enough resolution view that manual focusing is possible. Unlike traditional optical viewfinders which may use a ground glass focusing screen, the GH1 EVF takes a small portion of the scene and magnifies it 10X. This magnified portion may be moved around to any section of the live view. In manual focus mode, touching the lens focus ring will immediately turn on the magnification for manual focusing.
The MFT system standard specifies the lens mount flange to image sensor plane distance (flange focal distance) as 20mm, which is less than half that of typical DSLRs. [8] The effect is that the GH1 body is smaller in every critical dimension, especially depth, and is also lighter weight when compared to a typical DSLR. This 20mm flange to image sensor distance prohibits the practical implementation of the traditional mirror box and pentaprism optical viewfinder of the typical DSLR. The Panasonic electronic viewfinder is the solution to that packaging issue.
With an electronic viewfinder, in addition to providing a clear brighter than DSLR view, the user can also select between a variety of image aspect ratios (4:3; 3:2; 16:9 and 1:1) with a 100% image area through the lens in live view, something impossible with the traditional DSLR optical viewfinder.
The EVF allows additional flexibility is in information and situational awareness. The user may select various overlays so that more than 20 pieces of additional information are available at a glance to the user without removing the eye from the electronic viewfinder. For example, flash setting, optical image stabilization mode (there are 3), drive mode (single, burst, bracket, timer), image aspect ratio, image quality (RAW, JPEG or both), exposure indicator, ISO speed, shutter speed, aperture, record mode, white balance, composition grid lines and exposure histogram are just some of the available pieces of information in the EVF, all without ever having to move the eye from the viewfinder.
The EVF live view mode also allows a preview of the actual exposure in manual mode. The user can adjust shutter speed and aperture in manual mode and see the actual effect on the recorded exposure in the EVF. In addition to the usual depth of field preview, the GH1 allows a unique shutter speed effect preview, giving the user an accurate preview of the finished image blurring when using a slow shutter speed.
In low light, the EVF has another advantage, in that it can brighten up the scene, allowing the user to see more detail than might typically be possible with a traditional optical viewfinder, the same way TV broadcasts of sporting events at twilight show many more colors and detail than human eye can see.
The EVF has some disadvantages, however. In extremely low light at the sensor limits, image quality degrades into a grainy, and often lagging image. As a result, the GH1 is not strong in extremely low light situations. Although the EVF performs well in low light, and can offer a better view than optical viewfinders, at extremely low light levels, optical viewfinders will have the edge. In burst mode, when the main image sensor must pull double duty recording the image and also feeding a live view to the EVF, image lag may become apparent, and it can be difficult to follow a fast moving object in the viewfinder. As a result, the GH1, as are all current EVF centric MFT cameras, is not a strong action sports camera. With the EVF being an electronic display, the GH1 uses considerably more battery power than the traditional DSLR, requiring more frequent battery changes.
Virtually all the functionality of the EVF is available on the articulated 3-inch (76 mm) LCD display panel on the back of the camera. The EVF also has an eye sensor, so that the EVF will turn on almost instantaneously, switching off the LCD panel when the eye is brought up the EVF.
LUMIX G VARIO HD 14-140mm/F4.0-5.8 ASPH./MEGA O.I.S. LENS
Complementing the GH1 is a purpose built video optimized "kit" super zoom lens, the HD video-optimized LUMIX G VARIO HD 14-140mm/F4.0-5.8 ASPH./MEGA O.I.S. lens. This optical image stabilized (Panasonic brand name "MEGA O.I.S") is video unique because it is near silent in operation, designed with an internal direct-drive linear motor for fast and continuous accurate contrast detect auto focusing, and a silent, step-less (as opposed to the traditional stepped) circular (as opposed to the more traditional hexagonal) aperture diaphragm, ideal for smooth light control so important for video.
The 14-140mm lens is a 35mm camera equivalent focal length of 28mm wide-angle to a 280mm telephoto with manual zoom control. This lens is called a "super zoom" lens because it has a 10x magnification ratio as opposed to the more common and traditional zooms which tend to be in the 3x to 4x range. On larger sensor cameras (APS-C or larger), zoom lens tend to be large and heavy. The micro four thirds sensor provides some advantages in allowing a smaller, lighter, more compact zoom lens design. Even at a hefty (for MFT system lenses) weight at 460 grams, this lens is still relatively compact, includes in-lens optical stabilization and auto focusing, and very good (for a super zoom lens) optical performance. Nevertheless, the video optimized 14-140mm lens has been criticized as being too expensive for a kit lens, costing as much or more as the camera body. When the successor GH2 camera was introduced, Panasonic offered as another option, a much less expensive (and less capable) 3x zoom 14-42mm kit lens, in addition to the 14-140mm 10x zoom lens combination.
Body Colors and MSRP
The camera was available in three colors — black (suffix K), red (R) and gold (N). In the United States, initial MSRP was US$1500.00 (June 2009) for both the camera body and the 14-140mm kit zoom lens. Later on in the GH1 sales life cycle, the GH1 body only price was US$700.00 and the 14-140mm zoom lens only price was US$850.00
