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Why I enter "Live View" on my Nikon D5100, the mirror is locked up and I see a live view of whatever the CCD is seeing on the articulated screen just like a mirrorless system.

But when I go to take a picture, suddenly the screen shuts off, and I hear four separate noises. It sounds like the mirror is being lowered, then the shutter which has a kind of double "chaching" sound, and then another mirror which sounds like the mirror being lifted again.

But this makes no sense to me! The mirror has to be lifted to enter live view, as well as to take a picture. The shutter already has to be open for the sensor to capture light to be displayed on the screen. The image is already hitting the CCD as seems evident by the fact that it is being displayed on the screen. So why do I need to hear any noises at all? It's needlessly loud and delays the shot a bit. It seems like it should just record the shot. If I record a video it just does it without any extra delays or noise.

I looked in the manual and it says the screen will go off while the shot is being taken, but there wasn't any mention of this other nonsense. Why is this happening and how do I make it stop?

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    "this other nonsense" Just because it does not make sense to you does not mean it is nonsense. "how do I make it stop?" Stop using live view. ehabphotography.com/what-is-live-view-in-dslr-cameras dpreview.com/forums/post/56156701 – Alaska Man Apr 20 at 20:47
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    @AlaskaMan Well then explain it to me because as it stands it is nothing but nonsense to me. Maybe I want to use live view, to get the best of a mirrorless camera when I choose to. – Michael Apr 20 at 21:01
  • @AlaskaMan I read through that article but didn't see any mention of why it should go through these extra steps for every shot. It does mention something about these steps for autofocus, but on my model it focuses using the image (software contrast or something?) and not with the mirror. I confirmed this by setting manual focus and it still goes through these steps. – Michael Apr 20 at 21:08
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On a DSLR, when you use the viewfinder, the mirror is lowered, and a secondary mirror reflects some of the light to phase-based AF and exposure sensors at the bottom of the camera. These are accurate and fast.

When you use live view, the AF is contrast-based AF (the camera lens hunts until it find a position that maximizes contrast). This is slow (in your camera, likely much too slow for a moving object) and not too accurate.

So, when you take the picture, it can make sense to shortly lower the mirror again to use the faster and more accurate phase-AF sensors (and possibly the exposure sensors).

More recent cameras can have a better AF that uses the main sensor alone (for instance, the Canon cameras have "dual pixel" sensors that act as phase-based AF sensors), and may not need to switch to the external sensors.

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    CDAF is typically more accurate than PDAF; but CDAF is typically slower, so it could make some sense to switch when taking a picture IF taking a picture of a moving subject... but I am unaware of any camera that actually does. And the independent exposure meter is in the top of the camera (it still needs the mirror dropped); but it is not more accurate than direct sensor exposure measurement (live view exposure preview). – Steven Kersting Apr 21 at 12:32
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    @StevenKersting Most Canon DSLRs have a menu item for Live View shooting allowing the user to choose whether to use main image sensor based AF or to use PDAF sensor based AF. Both options are available according to the user's preference. – Michael C Apr 21 at 15:49
  • @MichaelC, that's interesting... isn't it talking about on sensor "dual pixel" PDAF vs CDAF and not the separate PDAF module? Either way, Nikon's don't have that option. – Steven Kersting Apr 21 at 16:35
  • @StevenKersting Maybe on the newer models with DP CMOS AF. This was there before DP CMOS AF was rolled out or included in most bodies. If "Quick Mode" is one of the LV AF options, it does a mirror drop that uses the PDAF sensor. The 5D Mark III has it as a menu option. I just discovered the 7D Mark II does not (I never shoot using LV with that camera). The 5D Mark IV doesn't have it either. – Michael C Apr 21 at 16:51
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    No. It uses the focus acquired with the PDAF sensor and takes the photo as soon as the mirror is out of the way. That's why it was called Quick mode - because when it was named dedicated PDAF sensor based AF was much faster than main sensor based CDAF, even after accounting for the time required to drop and raise the mirror. – Michael C Apr 21 at 17:04
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It's because on a (Nikon) DSLR, live view is part of the video stream with rolling shutter. This stream is usually not in a raw format and is typically reduced resolution. Some Nikon's have a "silent live view photography" menu option that allows recording a video frame w/o switching into still mode (mirror/shutter fixed).

In order to switch back to full resolution stills mode (w/o rolling shutter) the sensor has to be cleared, recharged, and then re-exposed to the light; the shutter typically closes in order to block the sensor from light during this sequence. And the shutter/mirror typically cycle together with the same input signal... because they normally should. On older/lower models the mirror also has to cycle in order for the lens to stop down (e.g. if the aperture was changed while in live view)... these cameras do not have live view exposure preview capability (for the same reason). Later models only cycle the shutter (e.g. my D850).

But this doesn't have to happen exactly this way... the Nikon D850 is the first Nikon DSLR that allowed full resolution raw stills w/ silent photography (live view video stills). This is really a result of more advanced video capabilities and it still involves the rolling shutter. I think the D4 allowed full resolution stills in jpeg format... I don't know all of the specifics, but it's safe to say you'll probably have less capability with older/lower models.

And I used to tape the mirror up on my D300 to prevent the mirror cycling/slap during live view photography; but I can't really recommend someone do the same.

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  • And didn't taping the mirror up lead to self-check errors? That's unexpected to me... – Ruslan Apr 21 at 15:03
  • @Ruslan, no errors because it doesn't know the mirror stayed up during the cycle; the arm/roller that moves the mirror is still free to move. I've seen stuck/jammed mirrors that also did not generate errors (but affected images/focus)... it could be somewhat Nikon specific... – Steven Kersting Apr 21 at 16:39
  • Why I thought it would error out is because of my experiments with inkjet printers, which watched that the print head gets to the left/right sides of its track at the correct time and gave up if it didn't. I suppose SLRs don't need that much robustness with the mirrors. OK, I now have a hope that I can get Canon 1100D to have tape-based "mirror lock-up" :) – Ruslan Apr 21 at 16:45
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    @MichaelC well, it does allow this, just tried it. I inserted a strut that doesn't let the mirror drop, and, although autofocus now doesn't work, viewfinder is unusable, and viewfinder-mode metering gets fooled into thinking it's too dark, the camera still does make the shots, and in LiveView mode I can even do proper metering and use the 10× magnified live image as a guide for manual focus. The sound of the up/down mechanism is still there though. Getting rid of this may require disassembly of the body to disconnect/shunt the motor (which might, in turn, cause some errors). – Ruslan Apr 21 at 19:48
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    Ah, it was set to "AF Quick" mode. Setting it to "AF Live" makes AF work indeed. – Ruslan Apr 22 at 19:10
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Because in the Nikon D3x00 and D5x00 series, as well as many previous entry level Nikon DSLRS and pretty much all Nikon 35mm film SLRs, the same mechanical motion actuates the mirror assembly and the aperture linkage. Once the mirror is up, the aperture can not be changed from the body. This worked fine when the mirror was always down until just before a photo was captured.

With the advent of Live View shooting, it's proved to be not quite as elegant a design.

If the aperture needs to be changed from what the camera is using for Live View, the mirror must cycle to change the aperture. Just one of several legacies from the pre-autofocus era that remained in Nikon AF film SLR bodies and digital SLRs for many generations of products in an attempt to keep all legacy F-mount lenses compatible with the newer cameras.

Only within the last half decade has Nikon started to adopt in earnest new ways of controlling the aperture electronically instead of mechanically. This has come at the cost of some newer bodies not being compatible with older F-mount legacy lenses. They straddled the fence for many years with their upper tier bodies by separating the mechanical actuators for the mirror from the actuators for the aperture, but continued to use the legacy design for the lower tier bodies such as the D3x00 and D5x00 series.

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  • so it sounds like newers series like maybe the D7x00 don't have this problem? – Michael Apr 21 at 16:08
  • Without taking the time to double check it, I believe that is the case. The current and all fairly recent Dxx0 series with only three numbers in the model name (or the Dx series with only one number in the model name) can change the aperture when in Live View. – Michael C Apr 21 at 16:09
  • Yes, but all Nikon DSLR's cycle the shutter/mirror when switching from video stills (live view) to normal photo mode (w/o rolling shutter)... even my D850 does. – Steven Kersting Apr 21 at 17:08
  • @StevenKersting Is what you are calling normal photo mode (w/o rolling shutter) viewfinder based shooting? Or Live View based shooting with mechanical shutter? – Michael C Apr 21 at 17:35
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    @Michael, the D850 allows the truly silent electronic rolling shutter for full resolution RAW files (reduced frame rate) that some mirrorless offers (e.g. Sony). Other recent Nikons also allow some form of silent live view photography (electronic rolling shutter), but at reduced quality/size. Most mirrorless also have a mechanical shutter which is faster; eliminates the rolling shutter effect and allows syncing with flash at reasonable speeds. – Steven Kersting Apr 22 at 18:37
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It sounds like you might be leaving a critical piece of information out: Under low-light conditions?

I've never owned a Nikon DSLR but it's probably because the live view has to refresh often (e.g. at least 24fps if not faster), so it boosts the ISO very high to be able to get shorter samples. Hence noise. It's probably also skipping any post-shot processing, but that's probably inconsequential next to the ISO issue.

But when it takes the actual photo, it's leaving the shutter open long enough to get a lower-ISO shot.

As to why all the extra noises, I can't actually answer that specifically for that camera, but can address it more generally. SLRs are evolving. The early Sony a7 series, for example, could be set up to take pictures while only engaging half of the shutter (front or rear curtain, user choice). This eliminated half of the noise. But you also lost some other capabilities. With newer a7 models, you can disable the shutter curtains entirely, relying 100% on "electronic curtain", which is essentially silent. (The a7 is also mirrorless, so it doesn't have that noise anyway.) Currently there are some inherent limitations with lack of shutters, but those are likely to be resolved in the future.

Personally I like the mirror "thunk", though it does add vibration. I also like the shutter noise when I'm shooting alone and noise isn't an issue. (Otherwise I prefer to be less conspicuous and moment-interrupting.) But the industry seems to be evolving away from both, or at least a physical shutter. Many cameras currently are in an in-between place.

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  • No, it does this all the time, regardless of lightning conditions. I just stepped outside into the bright sun and verify this. – Michael Apr 20 at 21:05
  • It sounds like you are saying that maybe my specific model is doing this because it is older and improvements have been made since then such that many models these days don't require this extra sequence of noisy steps to take the shot in live mode? – Michael Apr 20 at 21:06
  • Interesting about the noise. Not being familiar specifically with that model, I should defer to the other answers here. But yes - advancements are definitely making all SLRs quicker and quieter, usually with fewer steps (e.g. not putting mirror down for focus and/or exposure in live view). – Jim Apr 21 at 23:26

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