Gadgetory

hello I'm Gary sim from an authority today I would like to talk to you a bit about cameras specifically about optical zoom and digital zoom and the question before us today is is how can a smartphone which has a fixed focal length lens offer optical zoom well let me explain so let's start by talking about the difference in optical zoom and digital zoom now if you have a compact camera or a DSLR camera you may well have a zoom lens on it now when we're talking about zooming what we're really talking about is moving the focal length from one setting to another setting and inside the lens housing you actually find the different parts of the mechanism are moving closer and further apart to change how the light moves through the lens and when it arrives at the sensor now basically when you're using optical zoom there is no change in quality because the light is being manipulated before it hits the sensor and the sensor still takes the photo using its full resolution and using all of its full color and light capabilities and nothing is Olga digitally it all happens in the lens housing before the light actually gets to the sensor and when we talk about one time zoom 2 times zoom 3 times then what you're talking about is going from one focal length to another that's twice as large if you go from 50 millimeters to 100 millimeters that's 2 times zoom so for example here I have one of my Canon DSLR cameras and I've got a 55 to 250 zoom lens on it and as I start to rotate the zoom part here the mechanism inside is moving the different parts of the lens closer and further apart and if you go from 55 to 250 well 255 by 50 is five times so it's roughly a 5x5 times zoom lens now digital zoom is different digital zoom happens all inside the camera and is to do with how the sensor is taking the photograph if you think about it if you take a nice 18 megapixel photo of something that's quite far away if you crop that down to maybe only a three or a four mega pick or photo you can actually bring some of the objects much closer as they would appear in the photo but doing so you lose resolution or of course you could crop it down to the smaller area that you want to zoom in and then kind of resize it back up to a full 18 megapixels and then of course you lose some of the quality but that's basically what digital zoom is the camera basically either cropped it down and produces a smaller photo or actually cropped it down and then kind of magnifies it again in software doubling up the pixels so that you get a bigger picture zoomed in picture but actually you've lost a lot of the quality and of course that also means a lot of noise can get introduced now there are some very clever algorithms that can be used inside of the camera inside of your phone for doing this kind of digital zoom but at the end of the day what actually happening is the same amount of light the same large picture is being presented to the lens and then in software it's being manipulated so that only a part of that is shown and because it's only a part it seems as if it's bigger now smartphones come with a fixed focal length lens there is no mechanism for twisting the tube and making the lens go closer and farther apart it's a fixed focal length so how can phones offer optical zoom when there's no optics that can actually zoom well obstacle zoom is an option that you find on dual camera setups now there are two main types of dual camera setups available today one is where both lenses on both cameras are exactly the same they're both exactly the same focal length but maybe one has different properties so maybe one focus is more on monochrome or light gathering while the other one focuses on color and of course taking the detail of the picture the alternative setup which you find on phones likely 1+5 and you find it on the iPhone 7 plus is it actually the two lenses have different focal lengths so if one of them for example has a focal length of 24 millimeters and then the other one has a focal length of 48 millimeters that would give you the option of having a 2 x optical zoom now on the recently announced one plus five there is a difference in the focal length between the two lenses of around 1.6 and so what the one plus today will do is that when you go to zoom in digitally beyond 1.6 it can switch over to the other lens and then give you that optical zoom further on using the second lens now actually they claim a two times optical zoom on what they're really doing is from 1.6 to 2 they're actually just doing some cropping not for magnifying some cropping so that the picture of the resulting picture although it might be slightly smaller is actually giving you 2 times oon without using any digital magnification now it was an interesting question is what happened if you want just one point three time zone or one point four times ooh we eat in between the level of these two lenses well here there's probably two things going on this probably some distal digital zooming going on on the smaller lens until you get closer to the bigger lens and then there's probably like all dual camera setup there'll be a combination or the light coming in to both one picture and the other to perform some kind of processing to be done on the isp the image signal processor on the smartphone to produce the best results now while we have a slightly different solution with their hybrid zoom because what they have is the same fixed focal length on both lenses however one would be maybe a 20 megapixel sensor and the other might be they say something like a 12 megapixel sensor that's roughly what while we're doing and they again using both sensors with different amounts of information to kind of give you that zoom effect but it's not an optical zoom and they're quite rightly calling it a hybrid zoom so to recap optical zoom is actually only available on a smartphone when there is a dual lens setup and one lens actually has its optics set to be a greater magnification than the other lens and then using clever software the phone is able to interpret between those two and give you this kind of optical zoom from one setting to the other and of course this is one of the great advantages of using a dual camera setup with two different focal length lenses and we're seeing dual cameras becoming the standard now for flagship smartphones now if you want more detail about how optical zoom and digital zoom works inside a smartphone there's a great article over at yangon or for GOM website by robert Triggs which really does deal with this in yep and I've been able to cover now in this few minute video well I'm Gary Sims reminder authority I hope you enjoyed this video if you did please do give it a thumbs up don't forget to subscribe to and royalties YouTube channel hit that Bell icon so if you get notifications whenever we publish a new video please follow me on Twitter and last but not least don't forget to go over to Andrew authority calm because we are your 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