3/15/2026 at 9:07:52 AM
by ExAr
3/16/2026 at 5:57:28 PM
My uncle Richard is one of the inventors on Honeywell’s early phase‑detect autofocus. Patent US4333007A, which figures out both the direction and amount the lens needs to move instead of hunting.Modern systems like Canon’s Dual Pixel AF in bodies such as the EOS R5 are very direct descendants of that idea, just implemented on‑sensor with far more processing power.
Every time I see an article such as this, I beam with pride. (Pun intended).
by geocrasher
3/15/2026 at 9:07:52 AM
This article presents the inventive solutions Canon has found to shoot beams of light into the camera's viewfinder in order to light up individual autofocus points. Six different approaches are shown using six Canon DSLR models between 1994 and 2009.by ExAr
3/16/2026 at 12:46:51 PM
It's absolutely wild to me that this function would be so important as to justify all the time and effort to create not just two, but six entirely different ways of solving it.The first one seemed perfectly adequate to me. But I guess that's why I'm not a Canon engineer.
by myself248
3/16/2026 at 2:07:31 PM
I haven't used all of them, but I have used both the 9 point and the 45 point types, and the difference is massive. The 45 point was far, far more tactile and responsive. I don't mean speed of autofocus, but the actual way that the points sit over top of the viewfinder and light up, it's hard to explain. I'm sure part of that is software, but owning an older model and then trying out a newer one in the camera store in like 2013 really was eye opening, it blew my mind. The 9 point feels like a toy.by roblh
3/16/2026 at 3:19:26 PM
On the other hand in actual usage i don't think that they are really that different. It's useful for sports/wildlife for focusing closest moving target (and speed of AF on these cameras was not that quick so you were hunting focus anyway). Otherwise selecting some offset autofocus point is pretty niche. With more static subjects majority of photographers would use the single middle point, focus and then recompose.It's only with advent of smart focusing of mirrorless cameras with people/faces recognition where there is a big difference.
by omnimus
3/16/2026 at 5:58:16 PM
It’s impressive the optical complexity some of these systems use. Custom and complex prisms and mirrors to show the AF points.Arguably more complicated than the anutofocus optics. The engineering of electromechanical cameras fascinates me.
by generj
3/16/2026 at 10:43:00 AM
@ExAr I suspect your comment was downvoted to oblivion because people didn't realize you're the OP and thought you were an LLM summarizer bot :(by Sharlin
3/16/2026 at 10:49:03 AM
The comment reads like an LLM summary. And we don’t typically get an OP summary on a new post. Just post it and let people read it.by jagged-chisel
3/16/2026 at 11:11:50 AM
HN appears to encourage it, because it shows a text box which becomes a top level comment when you submit, although it isn't obvious that will happen.by xnorswap
3/16/2026 at 6:45:30 PM
That box doesn't become a comment, does it? It goes into the description that shows under the link.by stavros
3/16/2026 at 11:25:40 AM
Huh, that definitely explains it. I wonder how many people know that. In that case it's particularly unfortunate to downvote the OP simply for filling a field in the submission form! Sigh… I guess it's another case of LLMs having made the world a little worse for everybody.by Sharlin
3/16/2026 at 11:32:22 AM
I don’t think it’s because the comment was submitted. I think it’s because it reads like LLM output.Personally, I’ve only ever provided a summary if I felt the headline wasn’t clear enough.
by jagged-chisel
3/16/2026 at 12:36:03 PM
Yeah, but before LLMs we didn't have "reads like LLM output" as a downvote reason. In 2022 nobody would've had qualms with the phrasing of the comment.by Sharlin
3/16/2026 at 6:55:54 PM
I only realized they weren't a bot when i went to look at the other comment history.by mmmlinux
3/16/2026 at 1:36:08 PM
Thanks for pointing this out! I had no idea something like this would happen by filling in a comment box in the original post window.by ExAr
3/16/2026 at 10:56:47 AM
That's perfectly ok, they're using HN almost exclusively for promotion. See comment/submission history.by jacquesm
3/16/2026 at 11:24:53 AM
But the articles are well-researched, very high quality (the illustrations in particular are incredible), and in every way prime HN material, and there's no money involved as far as I can see. I definitely don't have any qualms about self-promotion of this sort of stuff.by Sharlin
3/16/2026 at 3:57:47 PM
Does AF use LIDAR nowadays?by brcmthrowaway
3/16/2026 at 5:45:56 PM
Maybe in some niches, but for most modern ILCs (e.x. Sony E mount, Nikon Z mount, etc etc etc) it is typically some form or another of On-sensor Phase Detection coupled with Contrast Detection for finer tuning.The biggest advantage compared to older SLR designs are that Phase Detection can now work with full light (vs whatever got split off on an SLR pentaprism for the dedicated AF sensor) and can work in conjunction with the contrast Detection for fine tuning focus.
Then, of course, all the predictive stuff added in the last 10ish years as far as processing sensor output to detect eyes/birds/motion/etc.
by whaleofatw2022
3/16/2026 at 7:14:06 PM
The only AF systems that use LIDAR are the one on the newest Hasselblad medium format mirrorless cameras (since DJI owns Hasselblad and can leverage the tech from drones/cinema cameras) and possibly some phones.I suspect it's fairly challenging to implement since the LIDAR sensor doesn't operate through the lens, so you'd have to continuously align the depth map with the image to account for parallax; plus it's only useful for close-ish distances (since the lasers can't be too powerful) and can cause unwanted focus behavior with windows or reflections.
by _ks3e
3/16/2026 at 5:42:06 PM
No. Modern cameras usually use a combination of contrast detection (pure image analysis checking the contrast of the region you want in focus), phase detection (an optical system where you split the income image in two and then compare them) and sometimes help of some sort of assist lamp.by tecleandor
3/16/2026 at 5:36:54 PM
I think only in certain cinema rigs. See DJI's products eg https://store.dji.com/product/dji-focus-pro-lidarby dillona
3/16/2026 at 5:52:46 PM
And just mentioning for people unfamiliar with this stuff, that's not a camera and not even an accessory for a camera. That's an accessory for an accessory. :DIt's a LiDAR that follows a subject and gets distance measurements, and then sends them to an additional accessory which is typically used to control focus in cinema cameras. That second accessory has a motor and is attached to a cinema lens that has certain threading or grooves where the accessory can grip and change the focus.
In cinema, the camera operator (usually) only moves the camera, but not the focus. For that, there's a 'focus puller'. A person who finely operates the focus, sometimes at a certain distance, using some sort of specialized control.
by tecleandor
3/16/2026 at 12:21:00 PM
hijacking the thread to ask: under 200€ DSLR to get started?by TheSilva
3/16/2026 at 12:28:10 PM
You can get a Canon 5D II or a Canon 6D for that. Older cameras for sure, but full frame with excellent sensors. And there are a ton of inexpensive used EF lenses available.Compared to moderns systems the main difference is the autofocus and video capabilities. Modern mirrorless have cosmically better tracking, eye detect etc.
by rrreese
3/16/2026 at 1:35:47 PM
Also speaking of older models I think it is important to repeat that the pixel count is not what define the quality of the image but mereley only how cropable the end result will be and it is only really useful if the higher pixel count isn't made of garbage. Accutance of the end result is in most cases much more important.For instance, human eyes can't perceive the difference between a 12MP and a 50MP image printed in a poster format from a typical 1.5-2meters viewing distance and 8MP is usually good enough for most large prints.
So I would advise choosing a second hand model taking shutter count, general state, lenses quality, autofocus speed and image stabilisation efficiency as more prioritary parameters than sensor pixel count.
by prmoustache
3/16/2026 at 5:54:11 PM
Two tricky things when it comes to pixel count...On one hand, you have to remember that huge MP doesnt do much if the glass can't resolve well enough.
On the flipside, I have to note that switching to high MP full frame makes it a lot easier to do good, clean crops. Sometimes I might care about a small portion of the frame but for composition reasons (e.x. can't get closer for one reason or another) I at least can lean on cropping more.
by whaleofatw2022