Modern digital SLR cameras are most often used for focusing optical viewfinder... Amateur photographers simply call him 'peephole'. Abbreviated Оoptical ВidoИskater called JVI. JVI they differ from each other by their optical crystal, coating and frame enlargement, focusing displays, enlightenment and the used LCD, LED displays. In this article I want to describe exactly the size JVI.
About the features of the optical viewfinder
You can view here about how the work is arranged JVI on a modern SLR camera. When shooting on different cameras, I very often find that different cameras have different JVIIt’s nice to work with some cameras because of the good JVI, other's JVI small and 'dark'. Usually in the characteristics of cameras, the description of the JVI is two parameters:
frame coverage - frame coverage, frame coverage (viewfinder coverage). For example, for the camera Nikon D5200 indicated that Frame coverage = Approx. 95% horizontal and 95% vertical
Frame magnification - frame enlargement (viewfinder enlargement). For example, for the camera Nikon D600 indicated that Viewfinder Magnification = Approx. 0.7x (50 mm f / 1.4 lens at infinity, -1.0 m-1)
Both of these options are very important. The coverage of the frame is set as a percentage, and shows how much space vertically and horizontally from a real image can be seen through such an JVI. For example, if it is indicated that the JVI has 95% vertical horizontal, then this means that in the JVI only 95% of the central image of what will be in the picture can be seen. After the picture is taken, an extra image will be added to it at the edges, which was not visible in such a JVI. Sometimes it annoys me that on some cameras parts of what I did not plan to include fall into the frame. Most often, this is the front lens of the lens of my videographer, part of the person in the frame, any other extraneous details. Such a picture then has to be cropped.
A rough example of what does not fall into the frame.
In fact, if the JVI displays only 95% of the image vertically and only 95% horizontally, then by the area itself, the JVI displays only 90% of what will be in the picture. It turns out that with such an JVI, 10% of the image is simply not visible. Manufacturers specifically indicate percentages in the width and height of the frame, since a figure of 90% in area could alert many when buying such a camera. Few people pay attention to frame coverage. Good cameras should have 100% coverage of the frame field, in such cameras everything you see in the JVI will be in the image and nothing extra will definitely get there.
If, on your camera, the JVI does not have 100% frame coverage, then Live View mode, which gives 100% field of view coverage, can always come to the rescue. Also, modern cameras with an electronic viewfinder almost always give 100% coverage. You can also just get used to it and count in advance the possibility that something extra can get into the frame.
Another important indicator of JVI is its direct magnitude.
The size of the OVI of different cameras. Photo taken from DPreview
The value usually corresponds to the Frame Magnification parameter. The more JVI, the more convenient it is to work with it. The real difference in the magnification of different JVIs can be felt when comparing cropped and full-frame cameras. Full-frame cameras usually have a much larger viewfinder with an increase of 0,7-0,8x, but cropped cameras come with an increase of 0,8-0,95X. The picture above shows how real the viewfinder is for different cameras.
Personal experience:
Usually 'bad' JVIs have old cropped DSLRs. In such chambers, for example, in Canon 350D, Nikon D40, OVI is very small, through it it is not always so easy to make out what is in the frame. Good JVI is especially important when working with 'dark lenses' and with manual focusing. You just get used to 95% trimming over time.
Conclusions:
Typically, photographers work with a SLR camera looking at the space with one eye through the JVI, this is a good, time-tested method of sighting. When choosing a camera for yourself, it is very important to have a good JVI, which will help in the work and will not make the photographer squint with all his might to see the details of the picture.
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Pentax K-50 and K-500, cameras with pentaprism and JVI with 100% frame coverage. JVI is light, very comfortable.