# RIDDLE: Where should the center of the image go after zooming ? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [February 24, 2014, 11:37am UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087 "2014-02-24T11:37:20Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 25, 2014, 10:53pm UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087/21 "2014-02-25T22:53:19Z")
In an ideal scenario, a zoom lens just _makes everything bigger_ - so nothing at all special should happen to the image except the middle portion being magnified to fill the frame. In practice, zoom lenses can’t just do that, because they are composed of a finite number of elements, which are of fixed shape, and only a few of them are movable - as a result, they usually introduce distortion to the image, which will be more pronounced at one end of their range. [Cite](http://en.wikipedia.org/wiki/Zoom_lens) > [@](#): > > Designers of zoom lenses with large zoom ratios often trade one or more aberrations for higher image sharpness. For example, a greater degree of barrel and pincushion distortion is tolerated in lenses that span the focal length range from wide angle to telephoto with a focal ratio of 10x or more than would be acceptable in a fixed focal length lens or a zoom lens with a lower ratio. I would expect the zoom lens of a consumer camcorder to be more prone to such distortion than an expensive removable zoom lens intended for an SLR camera. ---
**Author:** ![karol](https://avatars.discourse-cdn.com/v4/letter/k/977dab/32.png) [@karol](https://boards.straightdope.com/u/karol)\ **Post date:** [February 27, 2014, 6:32am UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087/22 "2014-02-27T06:32:29Z")
Enable captions. [http://www.youtube.com/watch?v=oE1PQhrAI30](http://www.youtube.com/watch?v=oE1PQhrAI30) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 27, 2014, 8:40am UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087/23 "2014-02-27T08:40:51Z")
So the middle stays in the middle for most of the zoom range, then it strays off. Exactly consistent with the sort of thing that might happen with optics that are anything less than perfect and ideal - an effect becomes more pronounced at the extreme of the scale. What’s your point here? Is is the concave Earth thing? Also, if the camera is levelled, how is it that the footage is so damn wobbly? Do you also have a hypothesis that the Earth is made of jelly? ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [February 27, 2014, 10:21am UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087/24 "2014-02-27T10:21:52Z")
> [@Mangetout](#): > > Also, if the camera is levelled, how is it that the footage is so damn wobbly? Do you also have a hypothesis that the Earth is made of jelly? It Must Be Jelly ('Cause Jam Don’t Shake Like That). ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 27, 2014, 8:18pm UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087/25 "2014-02-27T20:18:01Z")
OK, I watched one of your YouTube videos where you claim that the spherical appearance of the Earth is caused by fisheye distortion. Please explain how that works in images like [this](http://jimblackhurst.com/wp/wp-content/uploads/2010/11/tracy.jpg) one - where there is clearly no fisheye distortion, yet the Earth is round. ---
**Author:** ![karol](https://avatars.discourse-cdn.com/v4/letter/k/977dab/32.png) [@karol](https://boards.straightdope.com/u/karol)\ **Post date:** [February 28, 2014, 6:33am UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087/26 "2014-02-28T06:33:09Z")
> [@Mangetout](#): > > OK, I watched one of your YouTube videos where you claim that the spherical appearance of the Earth is caused by fisheye distortion. Please explain how that works in images like [this](http://jimblackhurst.com/wp/wp-content/uploads/2010/11/tracy.jpg) one - where there is clearly no fisheye distortion, yet the Earth is round. It is photo manipulated. Watch from **6:40 - 6:45** [http://youtu.be/JnWQhfuDZas?t=6m39s](http://youtu.be/JnWQhfuDZas?t=6m39s) ---
**Author:** ![karol](https://avatars.discourse-cdn.com/v4/letter/k/977dab/32.png) [@karol](https://boards.straightdope.com/u/karol)\ **Post date:** [February 28, 2014, 6:52am UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087/27 "2014-02-28T06:52:37Z")
[http://s1.postimg.org/wl377kyin/023.jpg](http://s1.postimg.org/wl377kyin/023.jpg) Why is the horizon in the mountains on eye level ? Same as at the sea. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 28, 2014, 10:22am UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087/28 "2014-02-28T10:22:30Z")
> [@karol](#): > > It is photo manipulated. Bollocks. But if you really do believe this is all a huge conspiracy, I don’t think there will be any way for anyone to penetrate that delusion. It would be entertaining to see you try to explain why the world needs time zones, and how it’s possible for anything to orbit the earth, but if you’re just going to link to more bullshit on Youtube, don’t bother. ---
**Author:** ![karol](https://avatars.discourse-cdn.com/v4/letter/k/977dab/32.png) [@karol](https://boards.straightdope.com/u/karol)\ **Post date:** [February 28, 2014, 3:52pm UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087/29 "2014-02-28T15:52:21Z")
> [@Mangetout](#): > > Bollocks. But if you really do believe this is all a huge conspiracy, I don’t think there will be any way for anyone to penetrate that delusion. > > It would be entertaining to see you try to explain why the world needs time zones, and how it’s possible for anything to orbit the earth, but if you’re just going to link to more bullshit on Youtube, don’t bother. You’re funny 🙂 ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [February 28, 2014, 3:54pm UTC](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087/30 "2014-02-28T15:54:59Z")
> [@karol](#): > > You’re funny 🙂 You’re not. [Previous page](https://boards.straightdope.com/t/riddle-where-should-the-center-of-the-image-go-after-zooming/682087.md?page=1)