Film-Tech Forum ARCHIVE: Can you tell anything about a lens from a flare?

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Posted by Mark J. Marshall (Member # 1409) on 01-17-2008, 12:32 PM:

Maybe this is a stupid question, and if so I'm ok with that.

Since lens flares can look very different, I've often wondered if you can use them to tell anything about the lens. I've seen perfectly round flares, and octagonal looking flares, and even triangular flares. I've also seen one flare, two or three flares, or tons of flares all stacked up on top of each other. All of these while looking at a single light source. Can anything be learned about the lens by looking at the flares? If not, what can cause them to be different shapes?

Thanks.

Posted by Ron Funderburg (Member # 4561) on 01-17-2008, 12:50 PM:

That is a good question and I have absolutely no idea but would love to read the answers. I do know that when you have lens flare on a scope film that it is often not complete stretched back out when it is projected.

I use to do photography and of course you really don't want lens flare except for certain effects. Motion pictures started to use, lens flare or rather not worry about it, in the mid 1960's and it became a bit of an artistic statement! the directors of photography prior to (hum what was the film oh yes) Cool Hand Luke avoided the flare at all cost to maintain realism. The Director of photography in Cool Hand Luke thought you over sanitized the shot if you tried to avoid it and gave it a duller look.

A quick look on the Internet shows that lens flare is covered all over it but I don't actually see anything that says what lens gives what kind of flare, now they even have software to create lens flare! So it could be that the software determines the shape of the flare rather than the lens. They now create lens flare where at one time they avoided it like a plague!

Of course, this doesn't answer the question so um don't know!

Posted by Bobby Henderson (Member # 840) on 01-17-2008, 01:26 PM:

quote: Mark J. Marshall
Can anything be learned about the lens by looking at the flares? If not, what can cause them to be different shapes?

Lots of different things influence how optical effects like lens flare and "bokeh" appear on the photographic image.

Different lenses vary on how many blades make up the shutter. A less expensive lens with a five blade shutter may capture pentagon shaped "discs of light" from things like out of focus street lights, etc. You can get five pointed lens flare stars around light sources in long exposures. A more expensive lens with more blades (eight or more) may capture nearly perfectly round discs of light.

Most lenses have numerous glass elements in them. Zoom lenses with image stabilization can have a lot of elements. If a strong light source, like the sun, is hitting the lens at a certain angle you'll see lots of different flare discs appear along that axis.

Even lens hoods can change the shape of out of focus discs of light ("bokeh") at certain long zoomed focal lengths. This sometimes happens with rectangular hoods over movie camera lenses. The circles in the background get their tops and bottoms lopped off, and at a long enough focal length the bokeh just becomes a rectangle shape. I haven't seen this optical effect in recent movies, but it certain seemed common in a number of 1980's movies.

Anamorphic lenses bring another layer of optical effects to images. It's usually pretty easy to spot when a movie has been filmed with anamorphic lenses. Circular lens flares get stretched horizontally. There's vertical football shaped bokeh in the background. I think those effects look pretty cool and make a movie look even more like a movie. Other people simply cannot stand those optical issues.

quote:
So it could be that the software determines the shape of the flare rather than the lens. They now create lens flare where at one time they avoided it like a plague!

Most lens flares and other optical artifacts usually occur naturally when the image is photographed. More expensive lenses are typically better at controlling and/or suppressing problems like lens flare and worse problems like chromatic abberation.

Artificial lens flare is available in Adobe Photoshop, certain 3D animation programs and various plug-ins for programs dealing with 3D, motion graphics or effects compositing. Generally speaking, such effects should be used vary rarely and with lots of tasteful restraint when doing so. Everyone who plays around in Photoshop will fart with that lens flare effect at least a few times. After awhile it only just seems to make any project look really cheesy.

Posted by Ron Funderburg (Member # 4561) on 01-17-2008, 01:35 PM:

Bobby I agree with you and like lens flare a lot in a film it does make it obviously a movie! The purist of the early days of Cinema avoided the lens flare for just that reason they were trying suspend disbelief and they felt that lens flare defeated that.

When I see lens flare I think it is bigger than life! And that is what most movies are suppose to be! kudos on the information I'm sure when I was a shutter bug I knew these things but ones mind tends to forget that which isn't called to the front!

I do remember working trying to get a lens flare in just he right place on shot so that we could not move the film and have it in just the right place on a double exposure! We did that double exposure 7 times and the first shot on the roll was the right one, who knew?

Posted by Bobby Henderson (Member # 840) on 01-17-2008, 02:19 PM:

quote: Ron Funderburg
The purist of the early days of Cinema avoided the lens flare for just that reason they were trying suspend disbelief and they felt that lens flare defeated that.

I guess it all depends on the kind of movie that is being made. Liberal use of lens flare in imagery would seem out of place in a pretty serious drama. But for something like an escapist action movie, buddy cop action comedy or some other popcorn chewy stuff like that crazy lens flare is cool.

Posted by Ron Funderburg (Member # 4561) on 01-17-2008, 02:48 PM:

Cool Hand Luke had lens flare in the road work scenes the sun was low in the sky in the early morning shots and late evening and they didn't use any filters or hoods. The director came to the camera man after the dailies were looked at said "Did you know that you have lens flare in these shots?"

To which the camera man said "So what is your point?"

"Well we don't have lens flare in movies."

The camera man was well experienced in the industry and answered "We can be the first, I like the effect."

Now Cool Hand Luke was a Drama with comedy in it and the effect is you kind of believe these men are burning up doing this hard manual labor in chains.

"What we have here is failure to communicate, you just can't reach some men." Sorry couldn't resist that one!!!

Posted by Brian Michael Weidemann (Member # 2243) on 01-17-2008, 02:52 PM:

I always wondered why IMAX films' lens flare shows up as pentagons. I never noticed the pentagons in other films or photography, so I figured there was something special going on in the IMAX camera lens assembly.

Posted by Tim Reed (Member # 137) on 01-17-2008, 03:03 PM:

Note that not all lens flares these days are real. I have several plug ins for After Effects that will put any kind of photo-realistic flare (even "anamorphics") into your shot. They'll also simulate flares at various focal lengths.

Posted by Ron Funderburg (Member # 4561) on 01-17-2008, 03:06 PM:

All I can find on Imax lenses is that they are Imax lenses it doesn't say spherical so not sure what it means but I would guess it has to do with the way in which the Imax lens works!

Posted by Mark J. Marshall (Member # 1409) on 01-17-2008, 03:15 PM:

Thanks for all of the quick responses. I'm not quite sure what this means though...

quote: Bobby Henderson
Different lenses vary on how many blades make up the shutter.

Posted by Kenneth Wuepper (Member # 1174) on 01-17-2008, 03:15 PM:

Some of these oddly shaped images are caused by the blades of the IRIS inside the lens and the reflections of that image among the internal surfaces of the lens. Most common as seen with very bright point sources of light in the field of view. Almost always when photographing a scene including the sun. [Frown]

Five sided images from a five blade iris.

Posted by Mark J. Marshall (Member # 1409) on 01-17-2008, 03:22 PM:

Ah, I think I get it now.

Posted by Joe Redifer (Member # 3) on 01-17-2008, 04:42 PM:

I haven't read everyone's replies, but you can certainly tell if a lens is anamorphic or not by the flare. In many programs I have which offer generated lens flares, you can choose the type of lens and whatnot and the flare changes accordingly, so I guess you can tell.

Posted by Bobby Henderson (Member # 840) on 01-17-2008, 07:51 PM:

Uh...yeah. I think "iris" would have been a better term to use. Or even "aperture." The "shutter" is actually the mechanical thing inside the camera body behind the lens.

Posted by Wayne Keyser (Member # 2420) on 01-17-2008, 10:34 PM:

Even the modest effects that come with Adobe Premiere Pro let you add lens flare to a shot.

Posted by Monte L Fullmer (Member # 2797) on 01-17-2008, 10:54 PM:

(Dragline: "If my man says he can eat 50 eggs, he can eat 50 eggs! so put your money where your mouth is!")

- "Cool Hand Luke"

Warner Bros
127m - 7 reels
2.35/1 Anamorphic
Technicolor IB print releases.

..sorry, couldn't resist either.

Posted by Frank Angel (Member # 248) on 01-18-2008, 06:16 AM:

A friend of mine has gotten into producing videos in an animation computer program. He recently discovered a plug in for lens flair, not only flair, but animated flair that he can move all round the image. From that point on, there wasn't a piece that he's authored that didn't have this damn flair zooming all over the place. At first it was cute, then annoying, now I just leave the room when the flair starts roaming around his shots. Bobby's "tasteful restraint" isn't part of his vocabulary.

Anyone ever see those star effects around points of light like a starburst that you see when they shoot what are supposed to look like diamonds or other jewels? Is that done with a special-effects lens? I am sure in digital they must have a plug in for that, but I have seen those decades ago, BD (before digital). I have even seen them rotate in a cheesey commercial for a diamond jewelry store. I assume they are made by a lens of some sort and they just rotate the lens, eh? Thing that I'm curious about is, how does the effects lens know which pinpoints of light get the starburst? I mean, if it causes those stars on random bright objects, if you have objects that have intensities of white light, why don't the starbursts form around them? What triggers a starburst, the intensity of the light or the contrast around a small area?

Posted by Kenneth Wuepper (Member # 1174) on 01-18-2008, 07:18 AM:

Frank,

Those Star like effects are created by a filter in front of the lens. There are very fine etchings in the filter glass and those cause the light to be diffused around a bright object. Since they are only filters, they can be rotated in front of the lens without effecting focus or aperture settings.

KEN

Posted by Tim Reed (Member # 137) on 01-18-2008, 11:34 AM:

Frank, all of the lens flare plugins can be animated.

Btw, I always thought star filters were cheesy. [Roll Eyes]

And since I am the King of Cheese, that is saying something! Haha.

Posted by Ron Funderburg (Member # 4561) on 01-18-2008, 12:22 PM:

Monte, Remember this exchange

Dragline "he beat you with nothing, just like this afternoon when he kept coming at me ... with nothing"

Luke "Sometimes Nothing can be a real cool hand"

Dragline "Move over boys let me sit next to my man COOL HAND LUKE"

tempted to run over to IMDB and see if I go it right but that is close enough! God I love that movie!

Posted by Monte L Fullmer (Member # 2797) on 01-18-2008, 01:59 PM:

Dragline: "Wipin'it off here, BOSS!"
BOSS Paul:"Go 'head Drag, wipe it off!"
BOSS Karr: "____spends a night in the'Box'."
Cap'n: "Report here says you got busted for destructing public property..
Luke: "Was cutting heads off of parking meters, Cap'n"

("Pop baby, pop")

Yes Ron, love this movie as well. First ran this flik in 1970 at a drive-in, then 6 yrs later at another drive-in...was so glad on the DVD release...

Posted by Tim Reed (Member # 137) on 01-18-2008, 04:20 PM:

Btw, "Cool Hand Luke" was one of the great works by the late cinematographer, Connie Hall - one of my heroes. Absolutely beautiful.

Also, do you remember that Lalo Schifrin's "Tar Sequence" music was later used by many television stations as their Evening News Theme?

Posted by Hillary Charles (Member # 769) on 01-18-2008, 04:31 PM:

When I think of star filters, I think of the 1970's daytime commercials for Slim Whitman. He'd be on a faux stage, lip-synching to "Una Paloma Blanca" with gelled spots behind him. The star filter would be rotated to accent the lights and the mood. [Razz]

And Tim, I don't know the music from "Luke" all that well, but I recall that one of the Philly stations (ch 3?) used John Barry's "007" for its own newscast.

Posted by Sean Weitzel (Member # 244) on 01-18-2008, 05:48 PM:

While most lense aperture/iris are leaves arranged in a circular patten, I have an old C-mount lens on my Bolex that has has three leaves arranged into a triangle shape which creates really cool flares.
I'm also a big fan of those BRIGHT blue horizontal flares that scope movies from the 70's were big on incorporating. Vilmos Zsigmond had plenty of them in Close Encounters of the 3rd Kind.

Posted by Tim Reed (Member # 137) on 01-18-2008, 06:14 PM:

quote: Hillary Charles
Tim, I don't know the music from "Luke"

Here's the theme. (This will only be on my server temporarily, unless someone can xnsfr it to the F-T server...thanks)

Posted by Hillary Charles (Member # 769) on 01-18-2008, 06:43 PM:

Thanks Tim, I can see why it would have been used as a news theme. You probably are familiar with "007" by John Barry, but you can understand why it also was used for the news.

Regarding lens flare, I remember a "news" story on something like "Inside Edition" in which people were claiming to have photographed some kind of doorway to Heaven! The story showed how they pointed their Polaroid 600 type cameras toward the sun (while looking throught the viewfinders [Eek!]

, if memory serves). The resulting shot definitely showed a vertical rectangular image in the center of the picture. Now, if those rubes hadn't blinded themselves by looking into the sun, they could have looked at the lens of their cameras to see the aperture with the exact same shape! [Roll Eyes]

Posted by Brian Michael Weidemann (Member # 2243) on 01-18-2008, 08:01 PM:

quote: Sean Weitzel
BRIGHT blue horizontal flares that scope movies from the 70's were big on incorporating. Vilmos Zsigmond had plenty of them in Close Encounters of the 3rd Kind

Those would be the ones that blinded me in practically every other scene in Transformers, wouldn't they? I figured those were post-production effects, especially since they glinted off the Autobots' CGI waxed body plates more than was called for.

Posted by Tim Reed (Member # 137) on 01-18-2008, 08:29 PM:

Hi, Hillary, thanks. Yes, re: 007.. it has that driving, important sound. Perfect for a news open. [Wink]

Posted by Bobby Henderson (Member # 840) on 01-18-2008, 11:16 PM:

quote: Brian Michael Weidemann
I figured those were post-production effects, especially since they glinted off the Autobots' CGI waxed body plates more than was called for.

Bright horizontal lens flares and elliptical halos are pretty common in a lot of modern anamorphic filmed movies. There's little need to add them in post production with CGI effects, but it does happen. Babylon 5 loved those elliptical halos even though the TV series wasn't in 'scope.

Posted by Tim Reed (Member # 137) on 01-19-2008, 12:34 AM:

[deleted]

Posted by Brian Michael Weidemann (Member # 2243) on 01-19-2008, 12:39 AM:

I only thought they were effects in Transformers because they reflected off the computer generated stuff ... unless they actually built and filmed those alien robots traditionally. [Wink]

Posted by Tim Reed (Member # 137) on 01-19-2008, 01:22 AM:

If they were reflecting off of CG, then they were certainly fake.

But, you knew that... [Wink]

Posted by Evans A Criswell (Member # 381) on 01-23-2008, 04:17 PM:

I love it when flares are put in something and the fake ones don't match the natural ones (wrong number of sides on the polygon), and the even worse, scope flare put in flat movie (Dungeons and Dragons).