About the sensitivity of phase focus sensors for mirrorless cameras

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Phase focus sensors, built into the sensors of mirrorless cameras, in many models have record high sensitivityup to -9 EV

For example, a mirrorless camera Nikon z9 the sensitivity of the phase focus sensors starts at -8.5 EV ('minus 8.5' stops). At the most advanced SLR camera Nikon D6 only from -4.5 EV With 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').

General view of the mirror

General view of a mirror taken from a digital SLR camera Nikon D700. The translucent window is not visible, but it is there. The window becomes visible if you look at the mirror from a different angle (see the title photo for this article)

First of all, this state of affairs is due to the lack of mirrorless cameras translucent mirror, which directs only a third of the light flux to the phase focusing sensors of SLR cameras. Phase focus sensors on mirrorless cameras receive all the light from the lens.

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

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Comments: 43, on the topic: About the sensitivity of phase focus sensors in mirrorless cameras

  • Oleg

    That bish mirror steers

    • Arkady Shapoval

      as it were, in terms of the sensitivity of the sensors - no, or what are you talking about?

      • Oleg

        Confused. If it’s just when seeding under difficult lighting conditions, which is better SC or BSC

        • Max Viktorych

          BZK apparently.

  • John

    I mean, Oleg, re-read the article again, since you don’t - I didn’t understand the first time

  • John

    But yes, the author of the article also writes simple things, writes in a complex language ...

    • Arkady Shapoval

      apparently soon tying shoelaces will be considered an incredible achievement, and only a select few will be able to read. And it's not even a joke anymore

      • Rodion

        Laces, according to one well-known franchise, should no longer be in 2015)))

      • Evgenii

        Not only everyone can read...

      • Max Viktorych

        So it will be. For sure, many schoolchildren do not know how to write in cursive. )

        • Rodion

          Just don't forget that the majority of useless and toxic comments on the Internet are not left by schoolchildren, but by men 45+.

          • Evgenii

            I will only be 45 in the fall :-)

  • Oleg

    Understood minus 8,5 ev. The word minus flew by. Another reason why the mirror will go away

  • Victor

    Zhzhote, gentlemen))) An article of three words and two commas has already turned out to be difficult to understand)))

    • Joe

      You are understating.
      Still, as many as 117 words (if you count with the title), 861 characters (if you count with spaces). It would take as many as 4 tweets to write such a text on Twitter!
      It is clear that this is difficult to understand.

  • Igor

    It would seem that not so long ago, autofocus was a weak point of mirrorless cameras, but now that's how it is)

  • Nicholas

    We ask Arkady to reveal this topical topic in more detail. For example, what physical size are these phase points (both on a separate SLR module and on a mirrorless matrix) How does this technology work in principle. How did it start 20-30 years ago and what is fundamentally new today. due to which the sensitivity of the phase points is increased. How is it that the phase points on the matrix do not prevent light from reaching the matrix. Well, and so on. The topic is very broad and interesting. Thanks in advance)

    • Rodion

      And they interfere with hitting, their size is on the order of several pixels. Therefore, in places where the sensor is located, the resolution of the photo is lower than where it is not - in fact, mathematics works there, “complementing” the image according to information from the pixels adjacent to the sensor.

      • Arkady Shapoval

        yes, they are in disguise. For example, Fujiks have this weak point

  • Eugene

    Well, nonsense in the article. We take an ordinary DSLR, for example, a D750, which has -3ev and puts z6 in its opponents, which had -4ev before the latest firmware, and now it’s even higher. And lo and behold, the DSLR wins in difficult conditions, while the z6 is dumb, fidgeting back and forth, and all because everyone is twisting the data as they want, and Nikon is no exception. After all, this light sensitivity was achieved with lighter lenses during testing, while tests were performed on a DSLR with darker lenses. The same garbage and in the camp of canon / sleepyheads. Just plain marketing.

    • after all

      Without pictures it's all verbiage. What are the criteria for the complexity of conditions and winnings? You can sum up such criteria that twice a crop will be better than a full frame.

    • Arkady Shapoval

      Tell me, with which lenses the sensitivity was achieved in both cases

    • in

      Oh, a man from the Mirror Sect has come. So, the sensitivity of the sensors does not depend on the lens

    • Max Viktorych

      You need to take two cameras with the same lenses and compare. For example, I can clearly see that the 50D kenon focuses more dexterously in a room lit only by a monitor than the 350d kenon. )) The first one is Whack, Whack, Peak. The second is whack, whack, trrr, whack, whack, whack, peak. Here of course the class is different, but nonetheless.

      • Arkady Shapoval

        You can’t put one lens with ZK and UPC. The adapter will take its toll

        • Max Viktorych

          Do these adapters have lenses or is it just a spacer like adapters for macro photography?

          • Arkady Shapoval

            when switching from fixed to fixed lenses, there are no lenses, but there is a logic for the operation of adapters, and sometimes there is even a special speed limit. Marketing, so that native new expensive lenses are bought under the bzk. Therefore, it will be extremely difficult to compare. But you can cheat a little. In the case of the Sigma E / L, there are a number of lenses that exist simultaneously for both zoom and zoom lenses (they were ported from zoom to zoom with a banal lengthening of the working distance).

            • Max Viktorych

              Oh, how it is!

  • Oleg

    Honestly, I didn't think about it, it's quite interesting. Thanks to the author!

  • after all

    And from what sources is the sensitivity information taken? There is a product passport, and everything else is verbiage.

    • Rodion

      Verbiage can, of course, take place, but the reason for the greater sensitivity here is concrete, physical - the absence of a mirror. And the sensors themselves are hardly any different for the ZK and UPC for cameras of the same technological level.

    • Arkady Shapoval

      From official.
      Data for Z9 (section 'Specifications' -> 'Autofocus' -> 'Detection range')
      Data for D6 (section 'Specifications' -> 'Autofocus'-> 'Detection range')
      Data for 1DXM3 ('Specifications' -> 'Autofocus (viewfinder shooting)' -> 'Focusing brightness range')
      Or do you really think that the data is taken from the ceiling? It's public information.

  • Eugen

    Succinctly

  • Seladir

    I immediately recall the statements of forum experts that matrix phase sensors are not like separate ones and will never reach their level. At the same time, support for focusing at f / 8 was a huge achievement for DSLRs, most cameras could only focus at f / 5.6. And then mirrorless cameras came along with their work at f / 11 and darker.

  • Sergei

    The Z9 has -8.5EV, the D6 has -4.5EV. Does the mirror absorb four steps?

    Maybe it's not in the mirrors, after all? Here is the Z6, for example - I know this for sure, in conditions of lack of light, it switches to contrast-finishing autofocus, and thus allows you to focus in darker conditions.

    About Z9 it is also written: focusing from -6,5EV, to -8,5 in _star focus mode_. I strongly suspect that the “star focus mode” is the contrast refinement of autofocus, and in real conditions it will be slow, like the Z6. This is indirectly confirmed by the fact that the D6 has no stellar focusing.

    Although two levels of difference is still a lot.

  • Max Viktorych

    All this is of course very informative, but ... I would like to hear an authoritative opinion on the latest models of DSLRs. Are they so cool compared to the 2008-2010 models and is it worth upgrading in light of recent events?
    It so happened that I can’t upgrade my rogue kit from 350d and 50d, but I’ve been dreaming about it since the time of 650d / 70d. )) And now, they say, all DSLRs can instantly turn into a pumpkin. (And I just rolled out my lip for 90d. Basically, of course, noisy ISOs strain in my devices. These are the pies. But if you don’t ask on the forums, they start to advise FF, so 5dm4, for example, or R5 in general. ((

    • Arkady Shapoval

      for starters, you need to step from the crop to the full frame, and the model is no longer so important, the same 5dm2 is still quite good, or even the same sony a7 bzk

      • Max Viktorych

        Is it necessary? ))

  • Jea reth

    On a rangefinder, you can quite clearly focus on yourself in conditions where you can still distinguish the contours of your eyes. Of course, everything starts to depend on the perspective of the end user and his experience. Well, I'm not talking about the darkening small windows of early or cheap cameras in place of the viewfinder.
    However, from personal experience: on my Kiev-4 lying around, I caught the focus in those conditions (almost complete darkness in the room), when both canons, without illumination, had long since given up even with the central sensors.

  • peace

    Good afternoon. ^_^
    Arkady, please tell me how to choose the right camera with which I can take pictures:
    1. Dynamic concerts in the dim light of the bar.
    2. Architecture (exteriors and interiors).
    3. Sometimes weddings, portraits.

    Do I understand correctly that the camera needs a good DD, quick focusing in the dark (preferably by faces), the ability to withstand ISO up to 6400 without strong noise? How to find exactly what you need among all the statements about high “ISO” in new cameras?

    Now I use an Olympus m5-2 + 12-40 lens at 2.8, but this kit is not friendly with darkness, and after reading this article, I thought about the importance of choosing, including the type of sensors.

    • Oleg

      Preferably a full-frame camera with a fast 2.8 lens at least

    • B. R. P.

      1. Only FF
      2. Here the lens, width / super-wide is of greater importance.
      3. Also a lens, like your Olympus, for FF 24-70 + portrait lens.

    • Arkady Shapoval

      Any modern full-frame zoom or zoom will suffice.
      Architecture is lenses and a tripod.
      A wedding is a skill and understanding of the process, again, lenses
      Dynamic concerts - high ISO and good lenses (bright telephoto or station wagon)

      Specific models: Canon R6, R5, Nikon Z6, Z7, Z6-2, Z7-2, Sony a7M3, a7m4, a7r2, ar3, a7r4, a7s3, etc.

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