[HN Gopher] Six ingenious ways how Canon DSLRs used to illuminat...
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Six ingenious ways how Canon DSLRs used to illuminate their
autofocus points
Author : ExAr
Score : 122 points
Date : 2026-03-15 09:07 UTC (1 days ago)
(HTM) web link (exclusivearchitecture.com)
(TXT) w3m dump (exclusivearchitecture.com)
| ExAr wrote:
| 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.
| myself248 wrote:
| 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.
| roblh wrote:
| 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.
| omnimus wrote:
| 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.
| Sharlin wrote:
| @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 :(
| jagged-chisel wrote:
| 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.
| xnorswap wrote:
| 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.
| Sharlin wrote:
| 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.
| jagged-chisel wrote:
| 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.
| Sharlin wrote:
| 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.
| stavros wrote:
| That box doesn't become a comment, does it? It goes into
| the description that shows under the link.
| jacquesm wrote:
| That's perfectly ok, they're using HN almost exclusively for
| promotion. See comment/submission history.
| Sharlin wrote:
| 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.
| ExAr wrote:
| 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.
| mmmlinux wrote:
| I only realized they weren't a bot when i went to look at the
| other comment history.
| TheSilva wrote:
| hijacking the thread to ask: under 200EUR DSLR to get started?
| rrreese wrote:
| 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.
| myself248 wrote:
| To add: Hit
| https://en.wikipedia.org/wiki/Canon_EOS_5D_Mark_II and scroll
| down to the very end, then click "show" to expand the "Canon
| EOS digital SLR timeline". This is an incredible collection
| of information that I can't figure out how to link directly.
| jmusall wrote:
| Direct link: https://en.wikipedia.org/wiki/Template:Canon_E
| OS_digital_cam...
|
| Not sure why it is a "template".
| rrreese wrote:
| The direct link is here: https://en.wikipedia.org/wiki/Temp
| late:Canon_EOS_digital_cam... You can get to it by pressing
| the `V` in `V T E` at the top left of any tmeplate
| prmoustache wrote:
| 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.
| whaleofatw2022 wrote:
| 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.
| hebelehubele wrote:
| Full frame sensor = full frame lenses = heavy and expensive.
| You need something light that you want to carry with you.
| Otherwise what's the point of having the best medium format
| camera + lens that you have at home, collecting dust.
|
| That means a camera APS-C or micro four thirds sensor might
| suit better to someone who is new to photography.
| omnimus wrote:
| I've always thought i am that APSC person and I ended up
| not taking the camera that much with me because it was
| small difference to compact camera i was carrying in my
| pocket. I thought it was skill issue because my photos just
| didn't have that bite/detail/look. The moment i got older
| full frame i realized that "look" has so much to do with
| the sensor size. In beginning i only had cheap 30euro
| manual soviet lens and even with that the quality of the
| photos just shot up.
|
| Full frame is heavy yes but it can be pretty affordable
| (lenses from china are becoming extremely competitive).
| criddell wrote:
| Is the SLR part a requirement? Would a mirrorless camera work
| for you?
| fooker wrote:
| Get a used 6D or 70D and a 50mm f1.8 lens.
| omnimus wrote:
| With the 200eur budget you wont make the 6D but you might 70D
| maybe even most of the lens. I would pay a bit more and get
| 6D though.
| omnimus wrote:
| I recently finally got my first fullframe (i've always used
| apsc crop sensors). I would say you want fullframe - to me it's
| really major difference in the look of photos. I would get apsc
| only if you really need portability. But for 200eur even old
| fullframe is tough.
|
| I've tried to get Canon 5D/6D but they are becoming pretty
| sought after (because of the availability of lenses). Another
| problem is when they are sold cheap they have huge shutter
| counts often way after their spec lifetime. Not sure about
| Nikon maybe there are some cheaps. You can probably get 6D mark
| I with pretty high shutter count for around 200e.
|
| Best usable 5D mark III deals i could find were around 450eur
| (thats camera from 2012). I ended up getting Lumix S5 (mark 1,
| from 2020) for like 500eur that is very different beast of a
| camera while having L-mount which is becoming only "open"
| camera mount (third party lenses are being "disallowed" by most
| manufacturers now).
| brcmthrowaway wrote:
| Does AF use LIDAR nowadays?
| dillona wrote:
| I think only in certain cinema rigs. See DJI's products eg
| https://store.dji.com/product/dji-focus-pro-lidar
| tecleandor wrote:
| 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. :D
|
| It'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.
| tecleandor wrote:
| 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.
|
| https://en.wikipedia.org/wiki/Autofocus
| whaleofatw2022 wrote:
| 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.
| _ks3e wrote:
| 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.
| geocrasher wrote:
| 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).
| generj wrote:
| 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.
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(page generated 2026-03-16 23:01 UTC)