Dual-lens smartphone cameras are coming

Contrary to what the headline implies, dual-lens smartphones came a long time ago. I had an HTC EVO 3D (<a href="https://en.wikipedia.org/wiki/HTC_EVO_3D" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;HTC_EVO_3D</a>) 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&#x2F;movies right on your smartphone.<p>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&#x27;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&#x27;t really all that spectacular.<p>But it sounds like what&#x27;s going on here, with the different focal lens stuff, is a lot different than just a 3D gimmick, and I&#x27;m interested to see what can be made of it.<p>Actually, one thing mentioned in the article -- depth analysis, to generate blurred backgrounds -- would, in principle, work on the HTC EVO 3D. Actually, I&#x27;m kind of bummed now that I didn&#x27;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 (<a href="https://www.lytro.com" rel="nofollow">https:&#x2F;&#x2F;www.lytro.com</a>) light field camera does.<p>BTW, in case anyone&#x27;s interested, I broke the EVO 3D about a month ago and got a Samsung Galaxy S4 Zoom (<a href="http://www.samsung.com/global/microsite/galaxycamera/s4zoom/" rel="nofollow">http:&#x2F;&#x2F;www.samsung.com&#x2F;global&#x2F;microsite&#x2F;galaxycamera&#x2F;s4zoom&#x2F;</a>) to replace it. The camera on this thing is amazing! It&#x27;s got a 10x optical zoom and a Xenon flash, just like a regular point-and-shoot. Of course, when I&#x27;m talking on it in public, I end up looking like a dorkwad, because it appears as if I&#x27;m talking into a camera, not a cellphone, but it&#x27;s totally worth it.

The title is strange; this seems to be describing dual cameras, not just dual lenses.<p>One important advantage I&#x27;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&#x27;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).<p>[1] <a href="http://cdn-4.nikon-cdn.com/en_INC/o/kiGHs2ZNM_El1gxcFVmhHA2Rdm0/Overview/Secondary-HDR.jpg" rel="nofollow">http:&#x2F;&#x2F;cdn-4.nikon-cdn.com&#x2F;en_INC&#x2F;o&#x2F;kiGHs2ZNM_El1gxcFVmhHA2R...</a>

With the title being a bit misleading (this isn&#x27;t about 3D), the key takeaways are that two cameras&#x2F;lens will allow:<p>1) Two different focal lengths&#x2F;zoom levels without having to use digital zoom<p>2) Better low light quality due to twice as much information<p>3) Better depth analysis: quicker autofocus, blurred backgrounds, augmented reality

Marketing : Let&#x27;s put 50 megapixel phones out there, people would love it and they would really distinguish us from all the iClones.<p>Engineering : But... <a href="http://xkcd.com/1014/" rel="nofollow">http:&#x2F;&#x2F;xkcd.com&#x2F;1014&#x2F;</a><p>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.<p>Engineering : Whatever...<p>Sensor manufacturers : Yaay !<p>HN guys : Wow, I got a dual cam app idea that FB would love to acquire... Ain&#x27;t 2 instagrams better than 1.

One thing that I&#x27;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)?<p>For example, how can it improve low light on the 1X shot for the pixels outside of the 3X frame?

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&#x27;d rather have them pay double for a much better camera, and be more competitive with the best mobile cameras on the market, today.<p>As for shooting 3D with dual-lenses, I don&#x27;t think there are many applications for that <i>right now</i>, but perhaps there will be in the future.<p>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&#x2F;avatars of yourself, again probably most useful in VR worlds&#x2F;games, and other stuff like that.

<i>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.</i><p>But the two lenses are taking the picture from different angles, and with different focal lengths! I don&#x27;t understand how matching of pixels is possible without an error greater than the noise they are trying to remove... It definitely can&#x27;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?

If this is so good why aren&#x27;t cameras using 2 lenses? Wouldn&#x27;t making zoom better by improving the one lens be cheaper than doing so by introducing other?<p>I am not mocking this, but am really interested. Because it seems like this idea would have already been tried &amp; if it were good would already have existed mainstream for cameras.

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 &#x27;eye&#x27; 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&#x27;t always flattering, and shooting Landscapes with 90&#x27;s can be equally frustrating.

I like the idea of this since you can use software to make better images.<p>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. <a href="http://en.wikipedia.org/wiki/Separation_masters" rel="nofollow">http:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Separation_masters</a>

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

I&#x27;d rather use that space to have a bigger lens and then carry around interchangeable lenses.