Need Debunking: Concert photograph from 8/27/21 (Billy Strings) fans claiming UFO. No eyewitness that I know of.

cleantones

New Member
source: Facebook

Over 600 shares as I write this. 14hrs after posted. Many fans think it's UFO. I suggest lens flare. One fan claims: "I'm a photographer. There's no way unless the light is directly at the the lens sorry not sorry".

Is there a good way to prove this is lens flare?

Billy Strings UFO.jpg
 
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Mick West

Administrator
Staff member
The the reflection of the stage light that's illuminating him.

It's a common type of internal reflection that occurs about the center of the image - essentially rotating 180 degrees.2021-08-29_13-23-42.jpg

It's not mirrored about the center as the image as been cropped. But it matches perfectly.

2021-08-29_13-27-18.jpg

Lights only need to be sufficiently bright to create internal reflections.
 

cleantones

New Member
Very good! The light is inverted and reflecting in somewhere in the lens housing. So it's not a lens flare but more of a reflection artifact of sorts. Very cool.
 

Mick West

Administrator
Staff member
Very good! The light is inverted and reflecting in somewhere in the lens housing. So it's not a lens flare but more of a reflection artifact of sorts. Very cool.
Most of what we call "lens flares" actually are reflection artifacts - just they are reflecting off the curved surfaces. The reflections like this one are reflecting off flat surfaces. You see them very commonly in phone cameras which have a flat protective outer cover on the lens, and I think it's reflecting the image projected on the sensor.
 

cleantones

New Member
Most of what we call "lens flares" actually are reflection artifacts - just they are reflecting off the curved surfaces. The reflections like this one are reflecting off flat surfaces. You see them very commonly in phone cameras which have a flat protective outer cover on the lens, and I think it's reflecting the image projected on the sensor.
Fascinating. Thank you VERY much!
 

Ravi

Senior Member.
Most of what we call "lens flares" actually are reflection artifacts - just they are reflecting off the curved surfaces. The reflections like this one are reflecting off flat surfaces. You see them very commonly in phone cameras which have a flat protective outer cover on the lens, and I think it's reflecting the image projected on the sensor.
A large part of the light hitting the sensor is reflected back to the lens/objective in front. About 25% of the light gets back reflected, and the cover glass can cause artefacts. This also is the reason why the reflection is a perfect mirror of the source (lamp).

I have used CCD cameras where we deliberately removed the cover glass to prevent these artefacts because the source (laser) was so bright.
 

Ravi

Senior Member.
I don't understand why the reflection seems to be focused so well.

I think the last lens (before the CCD plane) can be the cause, but it depends. The last one is most often a negative lens and thus concave and reflecting back to the CCD. Of course most often all surfaces are AR coated, but that still has 0.2% reflectance.
 

Amber Robot

Active Member
I don't understand why the reflection seems to be focused so well.
Internal ghosts can be at various levels of focus depending on which optical elements are in play. The in-focus ghosts will typically be the brightest just because the light is concentrated but it will also depend on the reflectivity of the optics in play. An example could be a reflection off the detector goes back through the lens(es) and off of a front window. Then the light coming back through will focus back on the detector. If the light bounces off an intermediate optic that is powered (curved) then the ghost won’t be in focus when it returns to the detector. Or a ghost caused by a double bounce within a flat unpowered optic (like a window or filter) will be pushed out of focus by the extra light travel path. The stereotypical “lens flare” will show most of these if the source is bright enough (e.g., the Sun) that the ghosts will show up with enough light.
 

JMartJr

Senior Member
Yes nice one, you can see the 2nd smaller light reflected in the sky from just under the the bottom curve of his guitar that confirms it.
I think I've got a third one...

Can somebody with camera savvy speak to why some bright light sources in pics like this produce reflections, while others int he same picture do not? It is an objectin I have had raised in conversations with folks about similar images in the past.
 

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Amber Robot

Active Member
I think I've got a third one...

Can somebody with camera savvy speak to why some bright light sources in pics like this produce reflections, while others int he same picture do not? It is an objectin I have had raised in conversations with folks about similar images in the past.
Some light sources are brighter than others so their ghosts will be brighter than others. What fools the eye is when the direct light source is saturated in the image, so you can’t see how much brighter it is than the others but the ghosts are unsaturated so you can better see the relative brightnesses.
 

Mick West

Administrator
Staff member
I don't understand why the reflection seems to be focused so well.
Light coming into the camera from a distant point is in roughly parallel light paths. All these paths are then bend and converged (i.e.focussed) to a point on the sensor plane. The partial reflection of this point goes back through the lens (diverging to roughly parallel), then reflects off the front and through the lens again (converging). So it's not going to affect the focus unless (I think) the light is close to the camera.
 
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