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Old October 7th, 2003, 04:48 PM   #1
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Lense Flare Help

Hey guys and gals, just had a quick question aobut lense flare on the Xl1s. One day of filming it started to wig out and everything turned green. Then it got better but the lense flare looks like this.
The sun was in some of the shots, but never directly for more than 5 secondes.

http://fish.boone.cc/xl1-lense-flare-2.jpg

http://fish.boone.cc/xl1-lense-flare.jpg

Any ideas?

Chris
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Old October 8th, 2003, 11:23 PM   #2
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Hey nice effect!

That is what you will get if you shoot straight into the sun, escpecially at the end of the day when the sun is closer to the horizon. I can easily see the sun sitting on top of the roof of that building.

Are you using any type of low-end UV filter in front of the lens? Did you have the built-in ND filter activated? What shutter speed and iris setting were you using?

You could try to use some sort of French Flag or bellows sun shade
http://leefiltersusa.com/CameraPrice/CamPriceSys.html

- or move your camera position to have the sun at your side or behind you.

- don
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Old October 9th, 2003, 01:02 AM   #3
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<<<-- Originally posted by Don Berube : Hey nice effect!

That is what you will get if you shoot straight into the sun, escpecially at the end of the day when the sun is closer to the horizon. I can easily see the sun sitting on top of the roof of that building.

Are you using any type of low-end UV filter in front of the lens? Did you have the built-in ND filter activated? What shutter speed and iris setting were you using?

You could try to use some sort of French Flag or bellows sun shade
http://leefiltersusa.com/CameraPrice/CamPriceSys.html

- or move your camera position to have the sun at your side or behind you.

- don -->>>

thx for the reply don, but the thing is...... The XL1 never made those green lines before. 1 day it just went wacko and started doing it on its self. The shutter and iris are adjusted to the conditions appropriate. Iris is never fully open....

my question is why are all these weird green/red/yellow showing?

Chris
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Old October 9th, 2003, 02:32 AM   #4
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Yup. That's what you get when you shoot into the sun, with a video cam or still cam. :)
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Old October 9th, 2003, 11:58 AM   #5
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>>>>The XL1 never made those green lines before. 1 day it just went wacko and started doing it on its self.

- Are you saying it just started to happen during a 'normal' shot situation where you were NOT pointed directly at the sun? If so, were there any bright lights in the frame? Did it eventually stop or is it still happening? If so, what conditions do you think typically invoke the effect?

>>>>The shutter and iris are adjusted to the conditions appropriate. Iris is never fully open....

- Well, not quite. Your images are overexposed. I'm curious to know if you had any ND dialed in or not - if you did not, you may have been using a very, very small iris opening (large f-stop number such as f/16). This may have caused some diffraction in the frame, with all that direct intense light going on (the sun was directly straight in front of you, low on the horizon) it may have been over-pronounced. So, that is why I asked what exposure setting you used. It would help to clarify the situation.

Is the effect still happening with your XL1S on shots where you are not directly pointed at the sun?

- don
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Old October 10th, 2003, 03:35 AM   #6
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We were shooting in 30fps and the shutter was 1/150 and the iris was about F3.4 (guessing) During the filming session everything turned green "did we fry a chip?" when i say green i mean the whole picture not just the lense flare. When the sun went down it appeared to be normal again. Now everytime we get those green lines as lense flare.


I have played with the shutter and the iris but it wont go away.

-fish

im sorry if i dont make any sense, XL1 is new to me :)
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Old October 10th, 2003, 06:56 AM   #7
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Chris, what can happen, although not obvious, is a fooling of the "dark current" compensation system due to a high amount of light in the outer zones of the CCD structure. As you maybe know, not all pixels in a CCD chip are meant to be active. Some of the border pixels are (supposed to be) positioned outside the CCD image field and screened off from the incoming light. They are there to be used as a sensing/compensation system for the (temp dependent) dark current. If the amount of lightblocking is not high enough (full lightblocking is known to be difficult...also a problem in LCD projecter structures) and/or some light (diffracted from a strong lightsource) hits these areas the "dark current" value gets higher and the compensation circuits will lower the offset. I think in your case, the blue channel has been hit resulting in a yellowish picture.
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Old October 11th, 2003, 12:45 AM   #8
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Chris, you have two different effects in your image. The vertical line(s) and the diagonal images emanating from the sun. The vertical lines are discussed in the XL1s manual and are a known phenomenon with CCD imaging devices.

Andre's explanation of your image turning colors is the most likely explanation of the color tinting you observed.

The diagonal objects emanating from the sun are called Ghost Images an explanation can be found at the end of this article
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Old October 11th, 2003, 01:31 AM   #9
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cool cool,. Thankyou for all the advise and help.

I will be sure to post the Trailer for our movie when we are finished.

www.extremeriderz.com

Fish
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