Live view

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Live view on the monitor of a digital single lens reflex camera

When Live View (also Live Preview ) refers to one with digital cameras and camcorders employed system that allows not the image composition via an optical viewfinder to make, but on the internal display. For this purpose, the electronic signal from the image sensor is transmitted to the screen in real time ( live ).

Technical development

Casio launched the first non-professional digital camera with a liquid crystal screen and live view with the QV-10 in 1995. Other manufacturers were working on similar solutions, and less than five years later, live view had become the standard for digital compact cameras .

It was not until later that live view also became popular with digital single lens reflex cameras. The first DSLR that offered live view as an alternative to the optical viewfinder image was the Olympus E-330 from 2006.

In September 2008, the Panasonic LUMIX DMC-G1 was introduced, the first mirrorless system camera with an electronic viewfinder that allows you to work exclusively with live view using this or the monitor on the back of the camera. Since smartphones and tablets do not use optical image composition settings, a live view mode is standard on these devices.

advantages

  • The view can show all the camera settings made for the image, i.e. the image brightness , the depth of field , the white balance and the effect of the exposure time in a reasonably realistic manner. This is the rule with most cameras. For certain shooting situations, especially if you want to use a flash, this mode should be switched off because the flash is not available during the preview.
  • Additional image information, such as a histogram with the distribution of the brightnesses , can be displayed in the image.
  • The manual distance setting is simplified with the help of the software magnifying glass. With the existing hardware , any image section can be displayed with a variable magnification factor. In the case of optical viewfinders, this is possible with sufficient focus of the viewfinder image with additional viewfinder magnifiers which, however, limit the field of view to a section from the center of the image.
  • The manual distance setting is simplified by highlighting clearly defined structures ( focus peaking ). The firmware determines edges with strong contrast and displays these lines with a conspicuous color or particularly bright.
  • With swiveling or folding monitors, the monitor image of the subject can be aligned with the viewer's eye. This also makes it possible to take pictures overhead, from the ground or even take self-portraits .
  • With live view, information about the sharpness and brightness of any part of the image can be obtained automatically before the picture is taken. Some of the automatic scene functions of modern cameras, such as face recognition, are based on this .
  • The image sharpness can be determined exactly where the image is created during the recording, namely by the image converter itself, if this is responsible for the live view display. Since no further focus sensor is required, there are no focusing errors due to poor adjustment.
  • The brightness of the image to be recorded can easily be monitored in the event of overexposure by displaying , for example, a zebra pattern or conspicuous warning colors in the corresponding image areas.
  • The brightness and contrast of the displayed image can be adjusted in poor lighting conditions or when using large aperture settings. For night shots, the brightness can be adjusted to the ambient light.
  • The display on the screen can be adapted to different recording formats set in the camera , such as 4: 3, 3: 2 or 16: 9, as well as the enlargements of the detail with the digital zoom .
  • The entire viewfinder image can be varied in size in order to be able to perceive the subject either as large and detailed as possible or clearly and quickly.
  • The live view always allows an exact control of the angle of view , also with the digital zoom , over a very large zoom range or with close-ups .
  • When creating panorama images from individual images ( stitching ), contours or sections of the already registered images can be displayed in Live View mode after the first image in order to improve the accuracy of the connection images.
  • Since there is no optical connection between a purely optical viewfinder and the image sensor, no indirect light from outside can reach the image sensor through the eyepiece of the optical viewfinder, which can lead to false light , especially with long exposures .
  • Live view is also permanently available for video recordings . The image can be displayed frozen after taking a picture so that it does not go dark like with SLR cameras. Since 2017 there have been camera housings that display a continuous viewfinder image even when taking series pictures .
  • With some cameras with a touch-sensitive screen and electronic viewfinder, the screen can be used to control the camera while the viewfinder is being used, for example when selecting information displayed in the viewfinder image, such as a menu item, the autofocus area or the position of the histogram.

example Pictures

The following images show some examples of augmented reality in live view during image capture:

  • Live view with ...

  • ... markings around the recognized and focused faces

  • ... highlighted red highlighting of all sharp edges ( focus peaking )

  • ... grid and grid lines for aligning object edges

  • ... auxiliary lines for vertical alignment of the camera ( roll and nod )

  • ... zebra patterns to identify the overexposed areas of the image

disadvantage

  • Electronic viewfinders or screens increase the power consumption of the camera and reduce the operating time per battery charge. Cameras equipped with an eye sensor on the viewfinder can activate it automatically and only when the viewfinder is used. When the viewfinder is used to play back recorded images, the image sensor can remain deactivated.
  • At very low operating temperatures, a liquid crystal display can be delayed or fail completely.
  • For a permanent display of the image, the image converter must be in continuous operation, for which it requires energy and which causes it to heat up. This generally has an unfavorable effect on the image noise and could lead to overheating of the camera with CCD sensors.
  • The automatic distance setting in live view is often based on a contrast measurement , which is available in a very variable manner via the signals from the image sensor, but is more complex to evaluate than the phase comparison measurement carried out with corresponding additional devices , as is usually done in single-lens reflex cameras with autofocus systems is used. In order to accelerate the automatic focusing, image sensors are increasingly being used that have an integrated phase comparison measurement and can therefore be operated simultaneously in live view mode. Furthermore, there are now combinations in which both a phase comparison measurement and a contrast measurement can be carried out with the aid of the image sensor. In addition, there are now predictive methods that enable precise and fast focusing of stationary or even moving objects exclusively with the help of contrast measurement.
  • Liquid crystal screens and electronic viewfinders show the images with a certain delay, so that when panning or fast-moving subjects the correct image section or image content may not be displayed. However, viewfinders with OLED technology now offer a refresh rate of up to 240 frames per second.
  • Simple electronic viewfinders have a low resolution or show a low magnification , which can limit the assessment of the subject and its sharpness. Electronic viewfinders such as the Panasonic Lumix DC-G9 mirrorless system camera now even show a larger viewfinder image (0.83 times magnification in relation to the 35mm format) than, for example, the optical viewfinder of the full-format with an image resolution of 3.68 million pixels. Canon EOS 6D Mark II SLR camera (0.71x magnification).

Single lens reflex cameras

With digital single-lens reflex cameras , the light penetrating through the lens is usually deflected by a mirror and prism , which creates an image in the optical viewfinder. The mirror is only folded away and the shutter opened when the shutter is released or the video is recorded so that the image sensor is exposed. The optical viewfinder is dark during this time. The sensor is only supplied with electricity and heats up during this time.

In order to be able to use live view with this camera technology, two different approaches are used:

  1. In the first digital single-lens reflex camera with continuous live view, the Olympus E-330 , a second image sensor with lower resolution is placed in the beam path. Part of the light is diverted to this and the image created there is shown on the camera's liquid crystal display. Since the mirror is in the normal position, the viewfinder image is available at the same time. The automatic focusing is done using the classic phase detection method. In a second mode ( macro ), the mirror is folded up and the actual image sensor provides the live view preview, with the autofocus using the slower contrast method. Because of the high design complexity, this technology is rarely used despite some advantages.
  2. With the further development of energy-saving CMOS image sensors , the technology of using the actual recording sensor for the image preview has largely established itself in digital single-lens reflex cameras. With this design, the mirror is always folded up in live view mode and the image is displayed on a screen. In this case, focusing is usually done using contrast measurement, but with some camera models it can also be switched to phase measurement; to do this, the mirror swings down for the autofocus and up again to trigger the exposure.

On smartphones and tablets

On smartphones and tablets, the live view mode is part of the standard camera software, as there are hardly any optical adjustment options for the image composition. The camera image in Live View mode can be adapted with filters using different mobile apps .

In the area of augmented reality , the Live View mode is used, for example, for navigation (e.g. with Wikitude or Google Maps ) or for direct image changes such as face swap . AR games use Live View mode either to capture and scan for the game or to project game elements onto the camera screen. Examples are The Sims Free Game and Minecraft Earth .

Web links

Individual evidence

  1. ↑ March 1995: Introduction of the QV-10 digital camera with LCD display. ( Memento of May 9, 2008 in the Internet Archive ) Casio website for the QV-10
  2. ^ KJ Kabza: Evolution of the Live Preview in Digital Photography. January 25, 2006, accessed January 9, 2016.
  3. ↑ March 2006: Olympus E 330 - first DSLR with Live View. ( Memento from April 7, 2013 in the Internet Archive )
  4. ↑ Panasonic LUMIX DMC-G1 - World's smallest and lightest digital interchangeable lens camera. accessed on October 27, 2019.
  5. ↑ Stiftung Warentest: Panasonic Lumix G1 system camera - a milestone in photo technology , test.de, accessed online on December 27, 2012.
  6. ↑ See for example in the operating instructions of the first system camera housing with electronic viewfinder Panasonic Lumix DMC-G1 from 2008 under "Checking the effect of the shutter speed" (page 92)
  7. ↑ A mirrorless future ?! - Optical versus electronic. publisher (accessed online on December 21, 2011)
  8. ↑ Viewfinder technologies: SLR principle, optical viewfinder and electronic alternatives - electronic viewfinder in digital cameras , ScanDig photo studio in Unterhaching (accessed online on December 21, 2011)
  9. ↑ Focused - phase versus contrast autofocus In: ColorFoto. 9/2011, pp. 27 to 32
  10. ↑ Markus Bautsch: Bildaufnahme - Hellitäten , Wikibooks Digital Imaging Methods , accessed on March 26, 2014.
  11. ↑ Andreas Jordan: Tried: Panasonic flagship Lumix G9 with pixel shift - outstanding viewfinder. In: Photo magazine. November 8, 2017, accessed December 31, 2017.
  12. ↑ Panasonic G9 - Extraordinary professional MFT presentation and first test images , photo hits, accessed on December 31, 2017.
  13. ↑ Martin Vieten: Briefly tried out: Sony Alpha 9 , photoscala from May 1, 2017, accessed on December 30, 2017.
  14. ↑ Seeker concept , Lumix G Experience, accessed on December 29, 2017.
  15. ^ Lars Kreyssig: Advantage: electronic viewfinder. digitalphoto.de from August 15, 2013, accessed on July 18, 2018.
  16. ↑ noise , www.ccd-sensor.de, accessed online on 5 September 2012th
  17. ↑ Test: system cameras achieve SLR level , yahoo finance, accessed online on September 5, 2012.
  18. ↑ Ken Utagawa, Yosuke Kusaka: Image sensor and image capturing device , patent application US 7715703 B2 of May 11, 2010.
  19. ↑ Dave Etchells: Panasonic GH4 A completely new AF approach - Tech Insights: Panasonic's DFD autofocus technology imaging-resource.com, accessed September 1, 2018.
  20. ↑ Benjamin Kirchheim: Advantages and disadvantages of the various autofocus systems , digitalkamera.de from October 2, 2016, accessed on July 18, 2018.
  21. ↑ Sony Releases 0.5-type OLED Microdisplay with Top-of-Class UXGA Resolution, Featuring the World's Smallest Pixel Pitch of 6.3µm , Sony press release dated May 28, 2018, accessed July 18, 2018.
  22. ↑ Mike Tomkins: New EVF makes it clear: the optical viewfinder's days are numbered , January 27, 2012, accessed online September 5, 2012.