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RF100-500 Purple Dot Dead Center

Started 3 months ago | Discussions thread
John Sheehy Forum Pro • Posts: 26,688
Re: RF100-500 Purple Dot Dead Center
2

nanciej wrote:

John Sheehy wrote:

It looks like some kind of flare. Are you using anything else in the optical path, like a filter?

That color is the color you get with near-infrared light, and some lenses are just not designed to manipulate near-IR light correctly. In some outdoor situations, there can be more near-infrared light than usual, relative to visible light.

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I’m out of my depth with the the IR info. Thanks. I’ll read on that. But…would this still result in this issue always being dead center?

I read many times in the past that people shooting IR would have a flare in the center of the image, or what they called an "IR hotspot", and I remembered that when I read your post. It only occurred with some lenses.

If this happened with 2 copies of the lens, then it is probably part of the lens design; a compromise they make when they design the lens with other priorities. Do you use a lens hood? That could help if that spot is coming partially from light coming from outside the field of view.

Edit: I see now in another post that you're using a filter.  That could give a colored flare even with white visible light.

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Beware of correct answers to wrong questions.
John
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