The Physics of Lens Flares

TaranT · Post by **TaranT** » Sat Feb 21, 2004 4:17 am

Something for everyone who is using, mis-using, over-using, or a-busing the lens flare effect:

The Physics of Lens Flares.

Sample:

Because lens flares occur on the lens, they will always appear to be in front of the scene. When artificially rendering a flare, it should always be drawn last.

Org Profile · Post by **VicBond007** » Sat Feb 21, 2004 11:54 am

So wait...hold on...gimme a minute to soak this in...you CAN'T have 3 at once?!

Seijin_Dinger · Post by **Seijin_Dinger** » Sat Feb 21, 2004 11:59 am

*not even reading the article*

If I recall correctly a lense flare is a specular highlight on the lense
for those who dont know, a Specular Highlight is the point one sees light reflecting off of a surface. (IE the little hot white spot in someone's glasses on a particularly bright day or under studio lights) as the lense is a single surface you will get one specular highlight, unless there are multiple light sources.
(Another note: in Video Production it is considered bad to have specular highlights in a persons glasses)

So basically the lens flare is just where the camera picks up light reflecting against its lens

Org Profile · Post by **Otohiko** » Sat Feb 21, 2004 12:03 pm

So... *sob* does it mean we're wrong to be sticking flares into people's teeth?

Kalium · Post by **Kalium** » Sat Feb 21, 2004 12:08 pm

Never let reality get in the way of your fun. I mean, we watch anime, don't we?

trythil · Post by **trythil** » Sat Feb 21, 2004 1:11 pm

seijin_dinger wrote:*not even reading the article*

If I recall correctly a lense flare is a specular highlight on the lense
for those who dont know, a Specular Highlight is the point one sees light reflecting off of a surface. (IE the little hot white spot in someone's glasses on a particularly bright day or under studio lights) as the lense is a single surface you will get one specular highlight, unless there are multiple light sources.

Specular highlights by themselves do not cause lens flares, even if the highlight occurs on the lens surface. It's due to reflection inside the lens structure.

Also, a specular highlight isn't the point at one which sees light reflecting off a surface. It's the area around the point where specular reflection is strongest; i.e. where the angle of incidence is the angle of reflection.

OmniStrata · Post by **OmniStrata** » Sun Feb 22, 2004 1:27 am

VicBond007 wrote:So wait...hold on...gimme a minute to soak this in...you CAN'T have 3 at once?!

*nod nod*

you cannot deny mah flares
heh heh

Mr Pilkington · Post by **Mr Pilkington** » Sun Feb 22, 2004 1:51 am

VicBond007 wrote:So wait...hold on...gimme a minute to soak this in...you CAN'T have 3 at once?!

I'm just as shocked as you are!

Well, maybe not "JUST AS." But I do simpathize.

Sort of.

TaranT · Post by **TaranT** » Sun Feb 22, 2004 4:32 am

VicBond007 wrote:So wait...hold on...gimme a minute to soak this in...you CAN'T have 3 at once?!

Whatever you think you can get away with before the audience starts throwing things. Or throwing up.

Otohiko wrote:So... *sob* does it mean we're wrong to be sticking flares into people's teeth?

You just need an anime character with "internal lighting" (fire in the belly!).

*****

The odd thing to me is that a Lens Flare is a CGI effect and would look appropriate with CGI or - if done properly - with live action material. A proper anime lens flare would be drawn in a minimal style like the cascade of hexagons that I saw once in an El Hazard episode.

About the article...the author only writes about still photography, not cinematography. If you have a scene that pans or zooms, then the lens flare needs to change in some way that is probably unpredictable without knowing the internal construction of the "camera" lens. It may be sufficient to just do a rotation and zoom of the lens flare itself. The audience won't know any better than you do. But a change of camera angle and position without a change in the lens flare may be noticed.

Seijin_Dinger · Post by **Seijin_Dinger** » Sun Feb 22, 2004 5:26 am

actually on a shoot in Seattle we did a zoom in move and we had a flare because we shooting towards the sun and the flare didnt change beacuse the zoom didnt ffect how the light hit the lense in the specular highlight, the only really change happns when you pan and something blocks the main light source in the pan