After reading Why don't DSLRs use laser rangefinders for autofocus? This question come in my head : Why camera don't use z-cam for autofocus (and allow extra raw creativity with z-data)

There is Phase detection AF, Contrast detection AF, but now we have ZCam. I think Active AF with ZCam could be a must have for fast autofocus at least for short distance, and add data usable in some creative or specialized domains.

Is-it ineffective ? Is-it very costly ?

In term of extra uses, I love to have a camera with ZCam focusing ability at least for faster low light focus, but also for fun raw developpement if i have RGBZ usable. And with appropriate software, tealing panoramic could be mutch easyier and probably many other case i don't imagine.

  • \$\begingroup\$ Polaroid cameras used to use sonar time of flight. \$\endgroup\$
    – Eric S
    Commented Jun 19, 2019 at 21:06

3 Answers 3


A simple answer:


A slightly less simple answer:

Power, and synchronization reliability.

Time-of-flight active range finding methods require you to project a signal out into the field, and to do so with something powerful enough to reflect back to the recording device with enough signal strength left to get useful readings off of.

That eats battery power, and while it may be useful in very low light or other challenging conditions, that is not a huge part of typical photography.

The other part is that knowing how far away something is from the camera doesn't actually do a lot for you when it comes to focusing a lens. In a carefully calibrated system it can be used in a round-about way to achieve focus, but it does not actually tell you anything about the focus.

So you can know that something is exactly 10.1543m away from the camera, and you can set the lens to the focus point that is was told should work for 10.1543m away, but this in and of itself doesn't tell you anything about whether or not the object is actually in focus... Since such a system does not rely on the focus of light through the image taking lens, then it has no means to confirm what the state of focus actually is.

Instead, camera manufactures have relied on systems that tie in closer to existing focusing methods. Canon has a 'focus aid' system built into many of their external flash units, which can project an IR grid into the scene to help the standard focus system lock on in low light for example. This grid is picked up by the standard optical focus system in the camera, and is based on how the lens is focusing light.

  • Uses existing tech already in the camera.
  • Uses power only on demand, assuming you remember to turn it off...
  • 1
    \$\begingroup\$ I no longer cover low-lit venues but used to attach a Canon ST-E2 for exactly the reason you state: the IR grid made for a better time focusing and was less obtrusive to the environment. Simply switching channels controlled whether I wanted to actually use the flash or not. I still end up using it from time to time for low-light AF help. \$\endgroup\$
    – OnBreak.
    Commented Jun 20, 2019 at 20:42
  • \$\begingroup\$ Just to be clear — the IR grid is just a focus assist light that happens to be IR. It's not a time-of-flight system. \$\endgroup\$
    – mattdm
    Commented Jun 21, 2019 at 2:30

In short — because the benefits of implementing the technology don't outweigh the development costs, support costs, and risk of fielding a dud to the market.

The Lytro light-field camera was able to capture the rays of the light field hitting the sensor. This allowed for very impressive capabilities, such as determining the plane of focus after the image was captured (i.e., in post), variable post-capture depth of field control, and 3D image creation. Their ultimate photographic camera, the Lytro Illum, was by most counts very promising. There was a lot of interest in the technology's potential, and it was hailed as a potential game changer for several applications of professional photography.

But alas, Lytro shut down all operations in early 2018. For all its promise and features, it wasn't interesting enough to disrupt the existing DSLR and mirrorless markets. For it to continue, tt would have required significant investment in either an entirely new platform (lens mount, lineup of compatible lenses), or partnership with an existing manufacturer. Because they shut down, it's evident that neither of those directions were deemed to be profitable enough to make the necessary investment.

Don't forget, it's not enough to merely have a demonstrably superior product or method. Technologies such as Lytro, ZCam, etc., have to be so superior that they can overcome both entrenched market participants (i.e., the incumbents who have a vested interest in not being disrupted) and the inertia of the installed user base — camera owners who have to be convinced enough to invest not only in new gear, but also invest in time to learn new tools, techniques, and workflows.

Regarding market adoption, there is always a small population of early adopters, tinkerers, tech zealots in search of the next cool thing, etc. But without good tools to manipulate, consume, post-process the new paradigm, compelling content is not created in sufficient quantities. And without existing content, there won't be a consumer demand for new content. It's a vicious cycle.

So you see, that in order to successfully field the type of compelling technology you're talking about, it's not enough to develop the tech. The toolchains, editing suites, data standards, metadata specs, promotional outreach, product support, social media presence, etc., all need to be considered and ideally in place, in order to fundamentally change how we create, manipulate, and consume photographic data.

Based on the fact that even Lytro couldn't succeed with great marketing and media buzz, I'm not surprised that ZCam and the like aren't a regular part of photography. At least, not for the time being.


Possible reasons:


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