# Spikes from Bright Lights on TV and Pictures **URL:** \ **Category:** Factual Questions\ **Created:** [January 29, 2011, 2:55am UTC](https://boards.straightdope.com/t/spikes-from-bright-lights-on-tv-and-pictures/569367 "2011-01-29T02:55:37Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [January 29, 2011, 2:55am UTC](https://boards.straightdope.com/t/spikes-from-bright-lights-on-tv-and-pictures/569367/1 "2011-01-29T02:55:37Z")
I have noticed it most in movies/shows where the camera will pan past a bright light (the sun, a streetlight, a searchlight) and the light will have 6 or 8 or so spikes coming out of it. I could not think of a good video example off the top of my head, but [here](http://www.inhabitat.com/wp-content/uploads/night-view-street.jpg) and [here](http://www.zooomr.com/z/photos/zoom/602181/size-8/) are photographic examples. It appears that the number of spikes are different depending on the type of lens? Is it some kind of lens flare, because I normally thinking of lens flare making the standard circular washed out regions like [this](http://en.wikipedia.org/wiki/File:Lens_Flare_at_Borobudur_Stairs_Kala_Arches.JPG)? Apparently it is not a [diffraction spike](http://en.wikipedia.org/wiki/Diffraction_spike), because that only happens if you use a mirror (like a telescope). What is it and why does it not happen all of the time? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 29, 2011, 4:23am UTC](https://boards.straightdope.com/t/spikes-from-bright-lights-on-tv-and-pictures/569367/2 "2011-01-29T04:23:35Z")
It’s caused by diffraction off of the corners of the [aperture](http://dptnt.com/2007/12/what-causes-the-sparkles-in-night-photos/) blades in the lens. ---
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [January 29, 2011, 5:25am UTC](https://boards.straightdope.com/t/spikes-from-bright-lights-on-tv-and-pictures/569367/3 "2011-01-29T05:25:42Z")
So, it is a “diffraction spike”, just a different kind. ---
**Author:** ![panamajack](https://avatars.discourse-cdn.com/v4/letter/p/47e85d/32.png) [@panamajack](https://boards.straightdope.com/u/panamajack)\ **Post date:** [January 29, 2011, 5:37am UTC](https://boards.straightdope.com/t/spikes-from-bright-lights-on-tv-and-pictures/569367/4 "2011-01-29T05:37:01Z")
Incidentally the shape of a lens flare may also be determined by the shape of the aperture (hence the hexagon in the linked picture). ---
**Author:** ![minor7flat5](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/minor7flat5/32/258_2.png) [@minor7flat5](https://boards.straightdope.com/u/minor7flat5)\ **Post date:** [January 29, 2011, 5:56am UTC](https://boards.straightdope.com/t/spikes-from-bright-lights-on-tv-and-pictures/569367/5 "2011-01-29T05:56:19Z")
Hmmmm… It’s hard to tell if that “Where the streets have no name” photo is really exhibiting lens-related spikes. They sell nifty star filters that do precisely this: [Star Filter Example](http://www.amazon.com/Hoya-STAR-SIX-Filter-star-effect/dp/B00009R988/ref=sr_1_4?ie=UTF8&qid=1296280381&sr=8-4) And they make them with two sets of lines (like graph paper), three sets, and four sets, allowing you to add awesome spikes to lights at night. ---
**Author:** ![postcards](https://avatars.discourse-cdn.com/v4/letter/p/8e8cbc/32.png) [@postcards](https://boards.straightdope.com/u/postcards)\ **Post date:** [January 29, 2011, 1:54pm UTC](https://boards.straightdope.com/t/spikes-from-bright-lights-on-tv-and-pictures/569367/6 "2011-01-29T13:54:47Z")
> [@minor7flat5](#): > > They sell nifty star filters that do precisely this: [Star Filter Example](http://www.amazon.com/Hoya-STAR-SIX-Filter-star-effect/dp/B00009R988/ref=sr_1_4?ie=UTF8&qid=1296280381&sr=8-4) I was going to mention these, but more for motion scenes than still photos. The examples linked in this thread seem to be time exposures; i.e., camera on tripod, shutter open for several seconds. For those exposures, no filter is needed. But for film, video and ‘normal’ still exposures, the filter is needed. (The etched lines are fine enough that the filter can be left on all the time; the effect only occurs when a light shines directly at it.)