Flair from bright objects.

Discussion in 'Exposure Discussion' started by Poco, Jun 2, 2003.

  1. Poco

    Poco Member

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    Why is it that the worst flair is caused by bright objects just BEYOND the field of view? For example, I've found it's often safer to photograph a bright object slightly in-frame and to crop it out in printing than to crop it out in-camera and risk a the band of flair it may cause.

    This problem seems to come up quite often in my shooting and I've always wondered why it happens and how to avoid it.

    BTW, for an extraordinary example of this effect, watch the "Jupiter & Beyond" section of Kubrick's "2001" (which was on last night and brought the question to mind -- great flick).
     
  2. Les McLean

    Les McLean Subscriber

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    I have a home made filter and lens shade holder that has never let me down. It consists of a thin metal plate that fits on to the camera and in turn screws into the tripod with the camera. On each side of the plate is a plastic threaded socket where I can screw in a 12" to 15" flexible tube with a clip attached. One clip holds any filter I wish to use and the other hold a piece of flat black card that acts as lens shade. The flexible tube is normally used on lathes to carry cooling fluid to the cutting head. I get some strange looks as I wander around the this attachment on my camera, for in addition to it looking like a Cheviot Tup with curved horns (a local male sheep), it is also a mix of rather vivid colours. However, I never have problems when shooting directly into the light and can quickly change filters.
     
  3. Jeremy

    Jeremy Member

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    Les,
    do you think you can post a picture of this contraption? I've got the basic idea and it sounds like something I could use.
     
  4. Poco

    Poco Member

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    I'm sure you're right, Les, that it's just a matter of better lens shading. The few sheep we get in this area are probably unspeakably spoken for, so I'll have to come up with some solution of my own.
     
  5. Jorge

    Jorge Inactive

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    I got a flair for not getting flare......:tongue:
     
  6. Les McLean

    Les McLean Subscriber

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    I'll make a digital picture of it in the morning and grovel to Sean to ask him how to add an image to a post
     
  7. bmac

    bmac Member

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    I think it would be easier to just add it to the technical gallery.
     
  8. Aggie

    Aggie Member

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  9. Les McLean

    Les McLean Subscriber

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    Tried that Aggie, it doesn't seem to work
     
  10. Loose Gravel

    Loose Gravel Member

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    I thought I already added this, but I don't see it.......

    This contraption is called a 'French Flag' by the movie industry.
     
  11. David Vickery

    David Vickery Member

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    Hello,
    When a light or another bright object is within the field of view of the lens (and not close to the edge) then the light rays from that object are close, or relatively close, to the optical axis of the lens. With the result being that most of those rays become image forming light rays.
    Whereas with a bright object that is very close to the edge of the field of view of the lens a large portion of the light rays are not able to contribute to the formation of the image but are still striking the lens. Because of the higher angle of incidence, they produce a lot of reflections off of the surfaces of the lens elements, with the result becoming a wash of non-image forming light---->Flare.

    Well, this sorta sounds good, doesn't it??
     
  12. David Vickery

    David Vickery Member

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    Oh, and you really can't avoid it--except by not having a bright light/object close to the edge of the lens field of view. Multicoating was created to help control this.
     
  13. Poco

    Poco Member

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    I have this feeling your explanation is right on, David. The thing that amazes me is that small lights (say in a night shot) positioned just out of view can result in such a narrow beam of flair coming in from the side of the frame. I've got a great example of this in print which I'll try to upload to the tech gallery over the next few days.
     
  14. Ole

    Ole Moderator Staff Member

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    David, Poco,

    I think that's the clue: Bright lights just outside the film frame will 1) be far off the optical axis, and 2) have a good chance of reflecting off any internal surfaces in lens and camera.

    I have a beautiful example of this, where the sun was just outside the frame. Since the film was Konica IR 720, I was also able to prove that multicoating is not optimized for IR light... I would never have thought that there were quite so many surfaces in a Zenzanon PE 40mm...
     
  15. Aggie

    Aggie Member

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  16. docholliday

    docholliday Member

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    For me, it's always seem that the more perpendicular a light source is to the front lens element, the less flare and the more parallel the light source is, the worse. And then there is the "the flatter the glass, the more flare" too.

    Seems like the "light piping" theory might apply here...can we say fiber optic properties?

    For weddings (receptions) I usually put fresnels in front of my strobe heads, so if I get a strobe in the shot, it becomes a star instead of flare.

    For the best flare protection, "light trap" methods are the most effective. See lens hoods for movie production and Arri cameras. The hood looks more like a barn door that is near fully closed (the outer tips of the flaps point inward instead of outward). I modified a small barndoor with a Cokin Bay60 ring and a ton of hot-melt glue to make mine. Never get much flare at all.
     
  17. fhovie

    fhovie Subscriber

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    I think in a lot of ways, flair is one more expressive tool that, can be understood and used for creative expression. I just got out of the darkroom - spending some time with a neg that I made on a moutain top where the sun was just behind a tree directly in from tof the camera. I was shooting a Rollei SL66 - using movements and a 50mm Distagon with no filter or shade. I was going for a very gritty look in the pine needles with the way the morning light shone off of them and I got a very interesting effect. 60% of the neg has exactly that gritty shine I was looking for but the area of the print where the sun was blazing around the tree, created a softness that set up real contrast to the sharp rest of the image - It will give me something to really toy with in the coming week. -Frank