Electronic Viewfinder (EVF) is a type of viewfinder used in television transmitting cameras or compact video cameras and is based on the use of a tube or a liquid crystal display . In fact, the electronic viewfinder is a compact video monitor that allows the teleoperator to observe the image formed by the transmitting camera. Until the late 1990s, the vast majority of electronic viewfinders were black and white. With the development of digital photography, the concept of “electronic viewfinder” has acquired a new meaning. So began to call the eyepiece sight of digital cameras , based on a liquid crystal screen, observed with magnification [1] .
Content
Television Application
The electronic viewfinders used in television technology can be of two types: studio and compact. Unlike the first type, which is a rotary monitor mounted on a stationary studio camera, compact viewfinders have an ocular design. Most compact viewfinders are equipped with a mirror mounted at an angle of 45 ° to the body, which reflects the picture of the tube or LCD in the eyepiece . Image flipping is compensated by changing the polarity of the horizontal or vertical scanning , depending on the location of the mirror. This design allows you to observe an enlarged image of a small-sized screen with one eye and has been preserved to this day, as the most compact option for placing elements. The ocular type of the compact viewfinder is less informative, because it allows you to view the image with only one eye, in contrast to the studio type.
Modern professional video cameras for television journalism are equipped with both types of viewfinder: ocular and folding flat. In this case, the ocular viewfinder is usually black and white, and is used when shooting from the shoulder. The second serves as an auxiliary color monitor, which is more convenient when working with a tripod. Modular cameras can be equipped with various types of electronic sight, depending on the task. In the studio version, a studio viewfinder is connected with a screen diagonal of at least 6 inches [2] , in the shoulder - eyepiece with a 1.5 inch screen [3] . Regardless of type, all viewfinders of professional cameras have electronic marking of display areas . In addition, the obligatory function is the overexposure indication (the so-called “zebra”), which displays the “punched” portions of the image in the form of areas of black and white stripes, inclined at an angle of 45 °.
Digital Photography and Cinema
Cheaper cost of liquid crystal displays and their distribution in digital cameras allows using the same type of viewfinder as an alternative to traditional optical viewfinders. Most modern digital SLR cameras have the ability to use an LCD display not only to control the footage, but also for sighting. The latter became possible with the advent of the so-called Live View mode, when the photosensitive matrix forms an image with the mirror raised and the shutter open [4] .
The possibility of abandoning the bulky optical viewfinder has led to the emergence of two new classes of compact pseudo-mirror and mirrorless cameras [5] . In modern digital photography, the eyepiece type of a visor with a high-resolution liquid crystal display is usually called an electronic viewfinder. Part of the mirrorless cameras is equipped with an eyepiece sight simultaneously with a flat one, which is used to control the footage. The eyepiece LCD viewfinder has several advantages and enhances shooting convenience.
In cinema, a television can be considered a kind of electronic viewfinder. The final device of the TV can be not only a director’s monitor, but also a studio-type screen fixed to the camera , making it easier to see the entire camera crew . The vast majority of digital movie cameras are not equipped with a mirror shutter and an optical sight, which complicate the design. Instead, an electronic viewfinder is used, similar to that on television cameras, but with a higher resolution.
Strengths and weaknesses
One of the main advantages of the electronic viewfinder is the invariable brightness of the image, which does not depend on the set aperture , lens aperture , and illumination of the scene [6] . Unlike an optical pass-through viewfinder, the brightness of which decreases in proportion to a decrease in the relative aperture, the electronic viewfinder always provides comfortable viewing, dimming only when the exposure is deviated. In pseudo-mirror cameras, this eliminates the complex mechanism of the jumping diaphragm and its repeater , since the observed image has sufficient brightness at the working value of the aperture.
The presence of an electronic viewfinder in most digital cameras makes it possible to accurately determine the exposure without an exposure meter based on test shooting and viewing the finished image. The ability to view the histogram improves the accuracy of halftone transmission, unattainable by any of the measurement methods. In camcorders and mirrorless cameras, accurate adjustment of exposure parameters and white balance is possible directly at the time of shooting. This is considered one of the advantages of mirrorless photographic equipment, since the photographer sees in the eyepiece a virtually finished image, with the possibility of correction in case of deviations [5] .
Another major advantage is the possibility of remote viewing. Modern professional cameras allow in Live View to display an image not only on the built-in display, but also on the monitor of an external computer connected to the camera [7] . Most mirrorless cameras released in the second half of the 2010s can display an image on the screen of a smartphone connected via Wi-Fi protocol. Due to the possibility of framing on the monitor, video cameras and movie cameras with a television set allow shooting from hard-to-reach places without the direct presence of a person. Panoramic heads of some modern camera cranes and trolleys are remotely controlled by an operator observing the image on the external monitor of the electronic viewfinder.
The disadvantages of the electronic visor include the need for constant power supply, unnecessary for optical viewfinders [1] . In addition, a full-fledged sight requires a high resolution screen and high-quality color reproduction, increasing the cost of construction. Changing the properties of the LCD screen at low temperatures makes it difficult to shoot in the cold.
In photo equipment, the use of an electronic viewfinder increases the shutter lag , since at first the latter must close from the position of sight, and only then exposure. In SLR cameras, when operating in Live View mode, the time delay sometimes exceeds the same as that obtained from a movable mirror.
See also
- Direct Sight Camera
- Mirrorless camera
Notes
- ↑ 1 2 Igor Skrynnikov. What is an electronic viewfinder (EVF) . Fototips (August 7, 2018). Date of treatment August 13, 2018.
- ↑ Studio camera, 2010 , p. 56.
- ↑ Leonid Chirkov. TV cameras 97 (Russian) // "625": magazine. - 1997. - No. 10 . Archived on October 16, 2012.
- ↑ Pros and cons of Live view (inaccessible link) . Reviews Fotoinn Store. Date of treatment January 24, 2014. Archived February 2, 2014.
- ↑ 1 2 Jim Harmer. 16 advantages of a mirrorless camera . Photo-Monster (June 13, 2017). Date of appeal September 2, 2018.
- ↑ Ken Rockwell. Mirrorless vs. DSLR Personal website (September 9, 2018). Date of appeal September 10, 2018.
- ↑ Canon Instruction, 2009 , p. 125.
Literature
- Yuri Mikhailovsky. Studio camera (Russian) // “MediaVision”: magazine. - 2010. - No. 4 . - S. 56-71 .
- Mikhail Lvov. Viewfinders (rus.) // MediaVision: Journal. - 2014. - No. 10/50 . - S. 71-80 .
- EOS-1D MARK IV Canon EOS 1D Mark IV . - Canon Inc., 2009 .-- S. 125-140. - 274 p. Archived November 9, 2013 by Wayback Machine