The device of the optical viewfinder. Feature of some Nikon cameras

The optical viewfinder of DSLR cameras is a tricky thing. On the one hand, in the classical view it consists only of frosted glass, a pentaprism or pentamirror and the viewfinder eyepiece itself. In fact, everything is much more complicated due to the fact that in modern SLR cameras there are visual additions in the viewfinder, an exposure metering system and a diopter adjustment of the viewfinder for the photographer's vision.

In general, the principle of the viewfinder structure in modern cameras can be described by the following image.

Viewfinder on modern cameras

Viewfinder device on modern cameras. Canon 7D camera design taken as an example

Please note that above the focusing matte screen, which forms the image, in modern cameras there is a special transparent liquid crystal LCD display (Transmissive LCD). The essence of Transmissive LCD is to create informational visual effects in the viewfinder, such as shown in the picture below.

Optical viewfinder with a number of additional visual effects

Optical viewfinder with a number of additional visual effects on the example of the Nikon D700 camera

As you can see, using the Transmissive LCD transparent display in the optical viewfinders, we can observe elements such as focus points and areas, framing lines, the backlight of the active focus point, the active lower and sometimes the side information panel. The information bottom or side panel is usually green and shows the most important camera settings, such as shooting mode, aperture value, ISO, shutter speed and many others. This is very helps a lot during shooting, because you don’t need to take the camera away from your face to check the settings on the main or secondary camera display. Modern cameras can even show a virtual horizon in the optical viewfinder.

Transmissive LCD has a special LED backlight that makes it glow informational visual indicators during work. I noticed that the LED backlight changes its intensity in different lighting conditions.

Principle of sight

Principle of sight

Some Nikon cameras have very strange feature: When the battery is removed from the camera, the viewfinder becomes very dark, dirty and grainy. This is contrary to common sense, because the viewfinder is a completely mechanical device that should not consume the power of the camera and show the real image that the lens forms. But cameras such as Nikon D80, D90, D700, D3 when the battery or battery pack is removed, they lose all normal ability to sight through the optical viewfinder.

Here is what is written in the camera manual Nikon D80 (18 page)

'If the battery is completely discharged or not installed, the viewfinder screen becomes dim. When a fully charged battery is inserted, the viewfinder screen returns to normal. '

The same can be seen in the instructions for other cameras, for example, Nikon D90, D700. In the instructions to Nikon D700, in the troubleshooting section, the following is indicated:

'Viewfinder is dark - Install fully charged battery'

Most likely, this circumstance is due to the fact that when the power is turned off, the transparent liquid crystal LCD display turns off and loses its normal ability to transmit light due to the specific features of liquid crystals. You don’t have to worry about the battery charge; the transparent display consumes very, very little energy. LED backlighting most likely only works when the camera is on. When you insert the battery back into the camera and look into the viewfinder, you can see how all the visual elements of the LCD display are initialized and turn off again, leaving only the framing grid if the latter was included in the camera menu.

Which Nikon cameras have this feature - I can't say. But I noticed a peculiarity that cameras with a pentamirror do not have this property. I believe the developers might not have disabled LCD display behind the focusing screen, and use the battery power of the system timer, but most likely they had serious reasons to resort to such measures. Also, I advise you to look at the page where it is described The structure of the mirror of the modern central hall.


Optical viewfinder - an interesting device. Some Nikon cameras have a specific viewfinder function that becomes unusable when the battery is removed, an effect related to the design of the optical viewfinder itself.

Help to the project. Thanks for attention. Arkady Shapoval

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Comments: 61, on the topic: The device of the optical viewfinder. Feature of some Nikon cameras

  • BB

    To fix
    '... D3 with battery removed ...' = 'battery E'

  • anonym

    My viewfinder becomes grainy (white dots) when the battery is pulled out, the nikond5500 camera. Whether this was a norm or not, the article reassured. Thank you for the helpful information.

  • Mikhail Ilyin

    When the nikon d90 camera in the case fell from the belt - the mechanism for raising and lowering the mirror stopped working (the motor in the camera was buzzing) the mirror rose and did not lower, the focusing motor and the sharpness sensor were undocked in the lens (they were docked by unscrewing five bolts from the end of the lens in 5 mm slot with sharpened matches). When pressing the aperture cocking button (bottom-right), the mirror cocked and remained at the top, the motor in the camera hummed when the shutter button was pressed, “Err” was displayed on the display on the left, shutter speed and aperture parameters were not indicated. He bent the bar of the diaphragm cocking lever with his finger (touched it strongly, almost bent it towards himself inside the lens, opposite the outer cocking lever, the move was initially light) and remained light - perhaps as a result the bar got into its regular place as it should (nikkor 18-20), or so it seemed to me. She just did not cock the diaphragm after the fall, now she does. After being transported to the master (maybe vibration on the road or the influence of the master room), he started working himself - the mirror began to be cocked and lowered from the “diaphragm” button and began to photograph from the “start” button. Only the active (but it did not burn before the fall) lower information panel in the viewfinder is off. It just does not light up at all, the grid and focus areas in the viewfinder are present, focus areas are active and are highlighted with red red light, if the shooting conditions do not correspond to the ISO exposure, if the focus is on the focus - a sound signal is given and the frame turns black - when you press “start”, the shutter works. I had to look at the shooting parameters in a small screen from the top-right (not a fig is visible) or in a large one on the back side to set ISO and exposure, which is very inconvenient. What is the problem, the viewfinder illumination is working, is it other LEDs? LED replacement possible? I didn't disassemble the camera, I'm afraid I won't put it back ...! Is it cheaper to replace the LEDs in the monitor, or to order an LCD monitor in the viewfinder ?, also make an audit of the mirror lifting mechanism. I don't think the problem is with the lens. With the attachment through the adapter ring of the Soviet lens, I shot without any problems, just set the aperture-focus. They put the lenses under a screwdriver - no comment.

  • Mikhail Ilyin

    Nikon D90 ?, Nikkor 18-200 lens

  • Mikhail Ilyin

    The active (but not burning until the fall) bottom information panel in the viewfinder does not light. It just doesn’t glow at all, the grid and focus areas are present in the viewfinder, the focus areas are active and are highlighted in red red if the shooting conditions do not correspond to the ISO exposure, if the focus is sharp - the sound signal comes out and the frame turns black - when you press the “start” button, the shutter triggered. I had to look at the shooting parameters in a small screen from the top-right (you can’t see a fig) or in the big one on the back to set the ISO and exposure, which is very inconvenient. What is the problem, the viewfinder backlight works, maybe these are other LEDs? Is it possible to replace the LEDs? I didn’t disassemble the camera, I’m afraid I can’t assemble it back ...! is replacing the LEDs in the monitor cheaper or ordering an LCD monitor in the viewfinder?

  • Paul

    Tell me please. We have D5100u In the viewfinder there are dust and lint. The matrix is ​​clean. After unfastening the spring and lowering the focusing glass, this LCD from the article is visible above it, and behind it, even deeper and closer to the pentaprism, I see these very specks of dust. How to get to them? How can I move this LCD to blow it out? even after removing the frosted focusing glass, dust particles are still not blown away and remain under the Transmissive LCD. Is there a YouTube video. Didn't find it myself.

    • Michael

      There is a petazerkalo, but not the essence. Most likely not. Removing the viewfinder shaft is necessary with subsequent disassembly

    • BB

      In a good service they said that if the dust got into the pentamirror, then it is irreparable (or the replacement of the pentamirror).

    • Dima

      No way, the two d5100s that I held in my hands are the same garbage, even with minimal mileage there is debris in the viewfinder. But the most important thing is that the matrix remains clean even after 2 years, not a speck of dust. So it seems to me that it’s better not to climb so as not to mess things up. The matrix is ​​clean and excellent.

  • Dima

    The D80 and D90 definitely have such garbage. The D5100 does not. It turns out that even if you just keep the camera turned off, it will slowly eat up the battery. Well, even here Nikon “surprised” not in the best sense of the word. Well, they can’t do it like don’t feed people bread)

    • Victor

      What is there “not like people”?)

      How long will it take for this crap to eat up the battery?)) Three years?))

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