My experience with EVI (electronic viewfinder) consists in communicating with Sony a7, a7 II, a7R, a9 cameras, some mirrorless Panasonic, Olympus and Fujifilm. For a long time I shot on SLR cameras with OVI (optical viewfinder), and after them it was very inconvenient for me to use EVI, but over time I felt all its charms and radically changed my mind.

On the Internet, I often see phrases like "Once I tried EVI, I realized that this is not mine." Such words can be said about me, but, fortunately, life made me communicate with EVI more closely and come to different conclusions.

Please note that OVIs are of two types - for SLR cameras and for rangefinder (mirrorless) cameras. The JVI design for these two different types of cameras is fundamentally different. In this article, by OVI, I mean a viewfinder specifically for SLR cameras.

EVI, power consumption and inclusion

One of the most serious drawbacks of EVI is considered volatility. In order to see what you want to shoot, in the case of EVI, the camera must be turned on. In this case, the matrix of the camera will be turned on, the processor and the EVI sensor will work. All this consumes energy, and even worse, it takes time to turn on the sensor, processor, and other hardware. As a result, there is a huge lag between turning on the camera and displaying the image.

Electricity consumption can be cured with more capacious or spare batteries - it's not a big problem for me... But the EVI lags when turning on, turning off, exiting the camera from sleep mode, activating the sensor after it was turned off while viewing the footage, and so on, get on your nerves. Lag when turning on EVI - biggest flawwhich I highlight in EVI.

This drawback can be easily solved - for example, always keep the sensors on, or just make the lags very short. I believe that in the future there will be no problems with power consumption and lags when turning on / switching a camera equipped with EVI.

Is the finished result really visible in EVI?

A strong advantage of EVI is the ability to see the finished result before releasing the shutter. But there are caveats here. The observed image is formed by a rather small sensor of 1-2 Megapixels, which does not transmit the entire amount of data received from the camera's matrix. In this case, JVI is more informative, the matte screen of which, in fact, has a very high resolution. Also, the camera's processor is not able to immediately apply all image enhancement add-ons, such as dynamic range control, color control, noise reduction, distortion, vignetting, and chromatic aberration. As a result, the image after the shutter is released may still be slightly different from the one that I observe in the EVI.

In the Sony a7 camera and many others, it is very noticeable that the image is still being finalized after the shutter is released. It often happens that after the shutter is released, the camera shows the received picture, 1-2 seconds pass and the picture changes its appearance - additional processing takes place, which could not be obtained immediately.

Also, the future result is not visible when working with pulsed light. True, this is not visible with JVI either.

And EVI does not always correctly convey the blur zone. The picture obtained in the EVI, in fact, is always the result of the operation of a fully electronic sensor shutter. But when the mechanical shutter is released with the front electronic shutter, the photo can acquire new artifacts, which were affected by this same mechanical shutter. In the end, the image in the EVI will be very different from the one that will be obtained after the shutter is released. For example, a similar problem reviewed here.

I really like that when working with EVI, a finished picture (obtained after releasing the shutter) can be viewed immediately without taking your eyes off the camera’s eye. In the case of the JVI, you need to take the camera away from your eyes and look at the main display to see the received image. It turns out that with EVI much less time is spent on monitoring the shot material.

As for the small differences from the image observed in the EVI and the final frame (after releasing the shutter), this is just a processor limitation, which can be easily cured in the future. Yes, and many cameras already fully display in EVI directly the frame that will be after the shutter is released - with all additional image quality adjustments turned on.

EVI in the studio

Usually, sighting through an EVI makes it possible to observe the picture that will be at the time of shooting, but this may not always be convenient, and sometimes it is contraindicated. This primarily concerns shooting in the studio using pulsed light. The bottom line is that in the studio all frames are usually shot with manual settings exposure. For example, in the studio it is most often used exposure control mode "M". Suppose I set ISO 100, F / 4.0 and 1/125 sec. With these settings, the camera’s EVI will display a black rectangle, since there can be very little pilot light (pulsed flashes will be used at the time of shooting). It is practically impossible to focus on and compose the frame in such conditions. To overcome this inconvenience, on cameras with EVI there is a function that disables “displaying pictures with actual parameters” and includes “display simulation”. In simulation mode, the camera does not use user-defined parameters. exposure, but selects its optimal ones, in which the EVI produces a distinct image, through which you can focus on sharpness and compose the frame. If you turn on the simulation, then in this case it will be very convenient to endorse in the studio.

In the Sony a7 camera menu, the function that is responsible for the display mode is called 'Display. Live View '(Setting whether to display settings such as correction exposure, on the display screen). This function can take only two values ​​“Display. Param. ON ”and“ Display Param. Off. "

When I first got into a studio with a mirrorless camera using EVI, I did not know about the possibility of simulation and it was very difficult for me to shoot.

Of course, simulation of the display can be useful for other types of shooting, for example, for shooting with very slow shutter speeds.

Inertia EVI

EVI suffers from inertia - when rearranging a frame, the display of changes may occur with a delay, and the EVI may slowly rebuild with a strong change exposure filmed scene. For example, if I was shooting in the shade of trees, and sharply pointing the camera towards a bright street, then in EVI instead of the expected type of street, for an instant I will get a white spot that has normalized and will take the expected form over time.

With a sharp change in lighting, the Sony a7 loses consciousness and within a few seconds adjusts to the correct exposure.

Most likely, this drawback can be eliminated and in the future cameras with EVI will be deprived of this drawback.

Pixelization

They say that one of the main problems of EVI is the pixelation of the image. Perhaps this was a problem many years ago when sensors for displaying images in EVI had low resolution. With the cameras that I indicated at the beginning of the article, I did not observe or did not notice the pixels of the EVI display.

If some EVIs have such a disadvantage, then over time the number of pixels on the EVI sensors will increase and everyone will forget about this problem.

Feeling of light

The EVI sensor has a constant or variable brightness within certain limits. On the one hand, this is a great achievement compared to the JVI. In the JVI, the brightness directly depends on the maximum aperture of the lens and the illumination of the scene. But constant brightness can play a trick on the eyes of the photographer. When shooting in bright light, I often saw that when I was vising through the EVI, my eye was tuned to a certain light intensity, and as soon as I took the camera away from my face and looked at what was happening without EVI, it took my eyes time to change to another illumination. The same thing happens when in the bright sun you bring the camera to your face, while in EVI you can’t see anything for a while until your eyes accommodate.

I think that this drawback of EVI can be solved with brighter sensors, as well as light sensors (similar to those that are in modern smartphones and automatically adjust the brightness of the display depending on the light).

The viewfinder is directly linked to the focusing system and exposure metering system

Speaking about EVI and JVI, you need to immediately understand that the technology for displaying the future frame is directly related to the focusing system. For JVI, very fast and fairly accurate phase focusing systems have been developed, which are based on separate sensors. For EVI, phase or other focusing sensors should be placed directly on the camera matrix (SLT cameras do not count, since there is a mirror there). So far, there is an opinion that focusing on mirrorless cameras with EVI is noticeably worse than on SLR cameras with JVI. But in fact, it all depends on the specific model. Modern mirrorless cameras already have phase focus sensors limiting sensitivity much lower (which is better) than the most advanced SLR cameras.

Separately, there are SLT cameras, which also use EVI, but at the same time they have a fixed mirror and phase focus modules characteristic of cameras with JVI.

Conclusions on EVI and JVI

Advantages of JVI

• JVI non-volatile, works even when the camera is turned off. True, modern OVI in some cameras have their own limitations, which are primarily associated with a transparent LCD display for displaying auxiliary information. I have considered this issue in detail here.
• Lack of inertia, minimal lag of the displayed scene, instant sight of the scene. Very important for reportage photography.
• High matte screen resolution with the possibility of replacing it with a more suitable one.
• The brightness of the JVI automatically changes depending on the scene being shot.
• Small shutter lag when using a fully mechanical shutter (with mechanical front and rear curtain). In turn, when using EVF, or Live View, before releasing the shutter, it takes time to close it completely (the shutter curtains must first completely close the shutter), and only after that the mechanical shutter itself is released (movement of the front and rear curtains). Sometimes this lag is just colossal (for example, in the Sony NEX-6). This problem is solved by using a fully electronic shutter, or using a front electronic shutter curtain (EFCS), but the latter method may have a significant problem, described here.
• Many users subjectively prefer the non-digitized image from the OVI than the digital image when sighting through the EVF.

Disadvantages of JVI

• The high cost of production and design complexity. For JVI, you need a very large number of mechanisms that can fail (tested more than once on personal experience). First of all, JVI needs expensive glass pentaprisms, mechanics of mirror control (two mirrors), separate metering sensor and separate focus sensor. When the cost of production is reduced, for example, when replacing a pentaprism with a pentamirror, the display quality decreases.
• For accurate and perfect focusing, the mechanisms of the mirror / second mirror and the focusing module need to be very precisely calibrated; it is sometimes extremely difficult or impossible to programmatically make accurate focusing with each lens.
• Simple ARIs have 90-98% of the frame coverage, the remaining percentages at the edges of the image are not visible. In expensive models, the percentage of frame coverage reaches 100%, but the cost of creating such a JVI increases. Details therefore you will find here.
• Noise at work. Part of the shutter noise It is created directly by the movement of mirrors and their control mechanisms.
• The movement of the mirror creates excess stirringthat may affect image blur. Some cameras have a tangible Mirror Shock.
• Focus area limited by focus points due to reduced additional mirrorresponsible for focusing.
• Image distortion... First of all, the OVI incorrectly displays the view of the out-of-focus zone, the bokeh when viewed through the OVI is displayed not at all the way it will look after the shutter is released. This is especially serious about the JVI based on a penta-mirror (pentaprism gives a clearer image). Also, when working in a backlight, the final image may have light artifacts (re-reflections, glare, etc.) that are not visible in the OVI.
• The opaque OVI screen, mirror and matrix may become dirty, which reduces comfort during shooting. In EVI, only the matrix is ​​contaminated.
• You cannot shoot video through the JVI. On cameras equipped with an OVI, the main display with the Live View function should be used for video recording.
• JVI has a certain dimming timewhen the mirror is in a raised state. In this position, focusing and metering also stop. exposure. In some cameras with EVI it is possible to constantly sight, even when shooting in a series, and focusing can work constantly, but for this you need to use an additional electronic shutter (not all cameras with EVI have an electronic shutter).
• JVI may suffer from flarethat affect metering exposure and / or illuminate the image for long exposures (this disadvantage is treated with a special eyepiece shutter, I examined this issue in more detail here). But the EVI is completely devoid of flares through its eyepiece.
• JVI requires use retrofocus wide-angle lenses (due to the presence of a mirror, the focal length of the lenses is lengthened).
• JVI does not allow sighting a stabilized image when using the built-in image stabilizer. To stabilize the image in JVI, you need to use lenses with a stabilizer. This problem is described in detail in the section 'An important disadvantage of the matrix stabilizer'.
• In JVI, sometimes you can observe / feel air pump effectwhich can be unnerving.
• With OVI, it is impossible to realize an arbitrarily high speed of continuous shooting with constant autofocus using the phase focusing module due to the closing / opening time of the mirror

Advantages of EVI

• When sighting EVI immediately displays that imagethat will be obtained after the shutter is released (with some reservations described in this article). Also, in the EVI it is convenient to see the real-time image settings and select the best option.
• The conclusion is very ba lot of supporting information. First of all, it helps to use a number of very useful functions, for example: focus picking, live bar chart, function - "zebra", electronic level and many others. Also, EVI allows you to instantly increase the selected part of the frame in real time, which can be very useful for accurate focusing.
• EVI allows you to view the photo you just received without taking your eyes off the eyepiece. Allows you to more quickly control the quality of the filmed material.
• The focusing method used with EVI is less prone to problems with back / front focus.
• Allows you to dig into all the settings of the camera without taking your eyes off the eyepiece EVI. In the case of the JVI, to access all the settings, you should remove the camera from the eye and turn on the main display.
• Constant, or automatically adjusted brightness at any aperture value, excerpts and the scene being shot. EVI brightness does not fall when closing the iris, for example, to view the depth of field.
• Simplicity of construction (unlike JVI does not require mechanical mirrors [two mirrors in case of CDC], matte display, pentaprism, optional focus sensor, optional metering sensor exposure and heaps of serving devices). Also, this design allows you to make cameras more compact and lightweight.
• EVI works silently (unlike clapping mirrors), and also does not create unnecessary movement from the movement of the mirror. Missing Mirror Shock
• EVI has a greater potential to expand the area of ​​the frame responsible for focusing. Theoretically, the entire area of ​​the frame may be responsible (or already responsible in the case of focusing by contrast) for focusing.
• Large (in fact 100%) percentage of frame coverage. In the JVI, it is not so easy to achieve 100% frame coverage.
• The use of EVI allows you to create non-trivial focusing capabilities: focusing on the eyes of people and animals in real time, predicting the behavior of objects in the frame.
• The ability to simultaneously sight through the EVI and connect in parallel other devices for image output. For example, you can connect a monitor to the camera with EVI, through which other participants in the shooting will see what the photographer is taking, without disturbing him at all.
• From the previous it emerges that EVI allows you to shoot video.
• EVI allows you to sight a stabilized image using the image stabilizer built into the camera. This will not work through JVI. This problem is described in detail in the section 'An important disadvantage of the matrix stabilizer'.
• Shutter release time may not be available when using the electronic shutter.
• With EVI, you can realize an arbitrarily high speed of continuous shooting with constant automatic focus. EVI does not have a constant need to close / open the mirror (taking into account the electronic shutter).
• Phase focus sensors, built into the sensor of mirrorless cameras, in many models have record high sensitivityup to -9 EV For example, a mirrorless camera Nikon z9 the sensitivity of phase focus sensors starts from -8.5 EV, and the most advanced SLR camera Nikon D6 only from -4.5 EV, while the most advanced SLR camera Canon EOS-1D X Mark III only from -4 EV (the lower the value, the better: '-8.5' is less than '-4.5') This is primarily due to the lack of translucent mirrorwhich directs to focus phase sensors SLR cameras have only a third of the light output. Phase focus sensors on mirrorless cameras receive all the light from the lens.
• The use of EVI partially forced the development of the capabilities of modern sensors faster. The transition to a fully electronic shutter is partly due to EVF and mirrorless cameras in general. The electronic shutter gives a virtually unlimited shutter life. A fully electronic shutter, for example, is used in Nikon z9.

Disadvantages EVI

• Insufficient brightness. On a sunny day, it may seem that the image in EVF is too dark (in the future, the deficiency can be corrected)
• Low resolution of the sensor, forming images for display in EVI. Here you can add low-quality sensors, which when sighted create various unpleasant visual artifacts (in the future, these shortcomings can be corrected)
• Volatility (theoretically it cannot be fixed, but in the future it can be improved by using sensors with lower power consumption and more capacious batteries, not everything is so bad now)
• Inertia, lag in image output (in the future may be fixed)
• Power-on lags or at low temperatures (may be fixed in the future)
• Shutter lag when using a fully mechanical shutter (with mechanical front and rear curtain). Before releasing the shutter, it takes time to close it completely, and only after that the shutter is released. This problem is solved by using a fully electronic shutter, or using a front electronic shutter curtain, but such an output can have a significant problem. described here
• Matrix heatingoverheating of the matrix, which in the first place can be negatively displayed at the noise level (in the future it can be fixed)
• Difficulty working in low lightrelated to the brakes of image display and / or displaying an image that is too dark (may be fixed in the future)
• In EVI are much more noticeable artifacts from the dirty matrix, this reduces comfort during shooting (may be fixed in the future with an improved sensor cleaning system)
• Phase focus sensorslocated on the camera sensor can be poorly masked and produce artifacts in the final image. May be fixed by new placement and/or masking technology in the future. Mirrorless cameras that focus only on contrast do not have this problem.

Some of these deficiencies have been corrected to one degree or another or are actively being corrected.

I can summarize that EVI technology has a lot to develop, its shortcomings can eventually be improved by the best hardware and software solutions. OVI technology has reached its logical end and does not have serious opportunities for improvement. At best, the JVI will move toward a hybrid JVI. Nevertheless, you need to understand that the JVI is a very ancient, proven technology that will please more than one generation of photographers.

Materials on the topic

1. Full frame mirrorless systems... Discussion, choice, recommendations.
2. Cropped mirrorless systems... Discussion, choice, recommendations.
3. Cropped mirrorless systems that have stopped or are no longer developing
4. Digital SLR systems that have stopped or are no longer developing
5. JVI or EVI (an important article that answers the question 'DSLR or mirrorless')
6. About mirrorless batteries
7. Simple and clear medium format
8. High-speed solutions from Chinese brands
9. All fastest autofocus zoom lenses
10. All fastest AF prime lenses
11. Mirrored full frame on mirrorless medium format
12. Autofocus Speed ​​Boosters
13. One lens to rule the world
14. The impact of smartphones on the photography market
15. What's next (smartphone supremacy)?
16. All announcements and novelties of lenses and cameras

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Material prepared Arkady Shapoval. Training/Consultations | Youtube | Facebook | Instagram | Twitter | Telegram