
Dual-lens smartphone cameras are coming - emanuer
http://www.engadget.com/2014/02/26/corephotonics-dual-lens-smartphone-camera/
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jawns
Contrary to what the headline implies, dual-lens smartphones came a long time
ago. I had an HTC EVO 3D
([https://en.wikipedia.org/wiki/HTC_EVO_3D](https://en.wikipedia.org/wiki/HTC_EVO_3D))
for more than a year. It came with two lenses, which allowed it to take 3D
stills and video. It also came with a special articulated screen that allowed
you to view those 3D images/movies right on your smartphone.

Sounds great, right? Well, I used the dual lenses to take a 3D still or video
maybe, oh, half a dozen times. Why? One reason was that the screen hurt my
eyes when in 3D mode. Another reason was that unless someone else had a 3D
screen, I wouldn't be able to share the files with them. And another reason
was that except for some gimmicky action effects in the movies, 3D isn't
really all that spectacular.

But it sounds like what's going on here, with the different focal lens stuff,
is a lot different than just a 3D gimmick, and I'm interested to see what can
be made of it.

Actually, one thing mentioned in the article -- depth analysis, to generate
blurred backgrounds -- would, in principle, work on the HTC EVO 3D. Actually,
I'm kind of bummed now that I didn't look into whether any existing software
could do it. I would have liked to have been able to generate 2D stills that
have an algorithmically generated shallow depth of field, sort of like what
the Lytro ([https://www.lytro.com](https://www.lytro.com)) light field camera
does.

BTW, in case anyone's interested, I broke the EVO 3D about a month ago and got
a Samsung Galaxy S4 Zoom
([http://www.samsung.com/global/microsite/galaxycamera/s4zoom/](http://www.samsung.com/global/microsite/galaxycamera/s4zoom/))
to replace it. The camera on this thing is amazing! It's got a 10x optical
zoom and a Xenon flash, just like a regular point-and-shoot. Of course, when
I'm talking on it in public, I end up looking like a dorkwad, because it
appears as if I'm talking into a camera, not a cellphone, but it's totally
worth it.

~~~
kalleboo
I had a different 3D phone (Sharp SH-12C) and absolutely loved it. Took all my
photos in 3D. They also display fine on a 3D-TV or monitor. I want to get a 3D
photo camera now that I'm on an iPhone, but it seems all those models have
been discontinued, which is a shame.

The 3D photo I took from the top of Mt Fuji is absolutely breathtaking, IMHO.
Gives a completely different sense of scale than a 2D photo.

~~~
batmansbelt
Can you still purchase 3d tvs? I understood that the manufacturers decided to
move in another direction.

~~~
dublinben
Pretty much every HDTV sold today is 3D ready. It's just not a selling point
any more.

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ryanjshaw
The title is strange; this seems to be describing dual cameras, not just dual
lenses.

One important advantage I'd expect but not listed: an increase in effective
dynamic range (the ability to capture more range in shadows and highlights in
the same photo [1]) may be possible if there's a sensible way to interpolate
data from the 3x and base focal length cameras (which seems to be the case, if
the low-light claims are to be believed).

[1] [http://cdn-4.nikon-
cdn.com/en_INC/o/kiGHs2ZNM_El1gxcFVmhHA2R...](http://cdn-4.nikon-
cdn.com/en_INC/o/kiGHs2ZNM_El1gxcFVmhHA2Rdm0/Overview/Secondary-HDR.jpg)

~~~
tracker1
That was my thought too... I was thinking that it was some new system of
lenses for physical zoom.

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jader201
With the title being a bit misleading (this isn't about 3D), the key takeaways
are that two cameras/lens will allow:

1) Two different focal lengths/zoom levels without having to use digital zoom

2) Better low light quality due to twice as much information

3) Better depth analysis: quicker autofocus, blurred backgrounds, augmented
reality

~~~
skywhopper
With the CPU/GPU power available to today's smartphones, I see a lot of
promise in software-assisted photo construction using multiple cameras. Sort
of like triangulating a 2D or 3D location in space using multiple 1D
measurements, different camera/lens pairs with differing strengths can be
combined to produce something greater than either one could alone. Nice!

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enscr
Marketing : Let's put 50 megapixel phones out there, people would love it and
they would really distinguish us from all the iClones.

Engineering : But... [http://xkcd.com/1014/](http://xkcd.com/1014/)

Marketing : Hmm.. how about 2 sensors, I mean 2 at the back side alone. 3D TVs
are a big hit. People would love them. I bet God had plans when he put 2 eyes
instead of one.

Engineering : Whatever...

Sensor manufacturers : Yaay !

HN guys : Wow, I got a dual cam app idea that FB would love to acquire...
Ain't 2 instagrams better than 1.

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jader201
One thing that I'm confused about though. If the two lenses are at fixed
depths (i.e. 1X vs. 3X), does this mean that the benefits of better low light,
blurred backgrounds, and augmented reality will only be supported at the
largest depth (3X), since most of the information would not be available for
the same shot at 1X (i.e. the 3X shot is missing two-thirds of the
information)?

For example, how can it improve low light on the 1X shot for the pixels
outside of the 3X frame?

~~~
jessriedel
It's actually even worse, isn't it? 3X has only 1/9th the solid angle, so ~90%
of the pixels wouldn't be covered.

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higherpurpose
I think the re-focusing stuff is mostly a cool-looking gimmick that not many
people will take advantage of. Instead of doubling their camera budget to buy
2 cameras, I think I'd rather have them pay double for a much better camera,
and be more competitive with the best mobile cameras on the market, today.

As for shooting 3D with dual-lenses, I don't think there are many applications
for that _right now_ , but perhaps there will be in the future.

If for example recording video in 3D will make it look much better when
watching it later with a VR headset, that could be pretty cool. It could also
be used for creating models/avatars of yourself, again probably most useful in
VR worlds/games, and other stuff like that.

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aaronetz
_As a result, noise is reduced and we end up with a cleaner picture -- just as
we would if we had one big imaging sensor instead of two little ones._

But the two lenses are taking the picture from different angles, and with
different focal lengths! I don't understand how matching of pixels is possible
without an error greater than the noise they are trying to remove... It
definitely can't be equivalent to one large sensor, as they claim. Unless they
can somehow route the image from one lens to both sensors? Is that even
possible?

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kang
If this is so good why aren't cameras using 2 lenses? Wouldn't making zoom
better by improving the one lens be cheaper than doing so by introducing
other?

I am not mocking this, but am really interested. Because it seems like this
idea would have already been tried & if it were good would already have
existed mainstream for cameras.

~~~
jseliger
_If this is so good why aren 't cameras using 2 lenses?_

The literal answer to this question is that most serious cameras have
interchangeable lenses; I shoot with an Olympus OMD EM5 and primarily use
three primes. A lot of people use zoom lenses, or primarily use zooms.

If you're only referencing cell phones, I assume that there is an obvious
trade-off between size and putting another lens in the camera.

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001sky
This is actually a great idea. Back in the early days of photo-journalism...it
was quite common to have a dual-camera setup for PJs. Or even 3 lenses (35,
50, 90), and just switch between the two. The benefits were multiple: better,
simpler prime optics. But also it turns out that most people develop a keener
eye. Zoom lenses suffer to some extent from ~infinite degrees of freedom,
which inhibit to some extent developing a good 'eye' for how each focal length
distors reality from a 3d to 2d transition. So, by adopting dual
optics...perhaps we can see faster, simpler and higher quality glass without
the loss of practicality. Shooting portraits with 28s isn't always flattering,
and shooting Landscapes with 90's can be equally frustrating.

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brixon
I like the idea of this since you can use software to make better images.

This is one of the reasons some really old color movies were able to be
restored so well. They filmed it with 3 lenses with one for each color (RGB).
Since there were 3 sources of data the restoration it was much easier to find
the best image.
[http://en.wikipedia.org/wiki/Separation_masters](http://en.wikipedia.org/wiki/Separation_masters)

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_mulder_
I imagine the 3D would be fairly limited because the lenses are so close
together. Would this be the case?

~~~
rahimnathwani
Cats' heads are smaller than ours, so I guess their eyes are closer together
than ours. Their agility doesn't seem to be hindered by poor 3D vision.

~~~
epi8
We use way more information than just binocular disparity to construct our
stereopsis. Since we extensive experience in our environment, we can use
relative sizes of known objects, atmospheric blurring, occlusions, we can move
our head and see the apparent shifts of objects, etc. The triangulation
provided by our two eyes is not the most powerful of our methods to estimate
depth.

These techniques are very hard to reproduce, however. Artificial 3D sensors
lean pretty heavily on some sort of triangulation, because it can be
formulated mathematically.

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goatslacker
I'd rather use that space to have a bigger lens and then carry around
interchangeable lenses.

~~~
RankingMember
I feel like you'd definitely be in the minority on that one. I like DSLRs too,
but for a phone, simplicity is key. I don't want to carry a bag of lenses with
my phone to take pictures with. It would also negate the benefit of having
something that doesn't look a big serious camera that puts off live subjects
and makes them uncomfortable.

