What is ghosting?

[kevinkt]

I have heard the term "ghosting" about bokeh and camera lenses, but I'm confused as to what it means.

Take the following article.

How To Test A Lens

There is a picture of what they say is "bad" bokeh, and one of the reasons is because it is "ghosted." What does that mean?

 

[EPPhoto]

It's like lens flare. A hood usually helps...and better glass. But in direct sunlight, there's no lens or hood combo that will eliminate it. "bad" bokeh is made by lower quality glass and doesn't have nice shape basically.

 

[Derrel]

Ghosting is a discoloration flaw that appears in images shot toward bright light sources, like the sun, or photo lights, or flashes, etc. "Ghosting" is a reflection of the lens's iris diaphragm, and often appears as multiple, diaphragm-shaped colored spots, of differing sizes, and often different colors, like red, faint yellow, faint green, faint orange,etc,etc.

Have you ever seen the cliche cinema shot, where a sunrise or sunset is photographed, like in a broad expanse of desert or mountainous territory, and there will be like, 15 separate, diaphragm-shaped colored defects in the image??? That's a pretty common example of ghosting, as seen in a cinema lens.

here, let me look up a link or two.

Okay :Lens Characteristics: Flare, Ghosting and Aberration  | Digital Camera Know-Hows | DIGITAL CAMERA LUMIX | Customer Support | Panasonic

:".....the phenomenon known as ghosting occurs when light repeatedly reflects off the surface of the lens and is seen in the image. Reflections occurring in front of and behind the lens' aperture give the ghost the same shape as the aperture"

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