tmx3 Posted March 30, 2018 Posted March 30, 2018 Hey everyone, Not sure if this is the right forum to ask this in (and I might post this same one in one of the biological sciences’ forums as well), but I had a quick question for anyone who has a solid understanding of how bats respond to photographs (and light)—and vice versa (the behavior of light as it captures a photograph of a bat): When taking a picture of a bat you happened to have found, is it normal to have disruption in the photo’s light-frequency, so much so that there are areas of dark bars in the photo? In the photo with the dark bars, the camera lens was within a foot of the bat. I’m wondering, do bats emit on the molecular level some kind of electro-magnetic frequency that disrupts a camera which tries to photograph it? Open to all ideas/discussion/questions... Just trying to figure out how/why this happened. All other photos were clear; only when the lens was within a foot of the bat would the photograph not be captured. Tried researching it but can’t find an article that explains it. Thanks!
Phi for All Posted March 30, 2018 Posted March 30, 2018 ! Moderator Note We've found it's better to have a single discussion thread we can move around if needs be, rather than starting multiple discussions in different sub-fora. I've hidden the one in Ecology & the Environment.
Strange Posted March 30, 2018 Posted March 30, 2018 1 hour ago, tmx3 said: When taking a picture of a bat you happened to have found, is it normal to have disruption in the photo’s light-frequency, so much so that there are areas of dark bars in the photo? Interesting. I can only think that the ultrasound is affecting the camera somehow - causing jitter in the lens or something ... I tried googling for this but the results are all about ultrasonic imaging.
tmx3 Posted March 30, 2018 Author Posted March 30, 2018 28 minutes ago, Strange said: Interesting. I can only think that the ultrasound is affecting the camera somehow - causing jitter in the lens or something ... I tried googling for this but the results are all about ultrasonic imaging. Hi, thanks for your response. I meant to add, the bat wasn’t screeching when the shots were taken. He was quiet. How can there be disruption caused by ultrasound in the light waves or what-have-you (sorry, not well versed with physics terminology), when the bat isn’t making sound? I mean, imagine taking a photo of your pet cat when he’s not meowing—same thing applies here. The bat was not making sound at all, and yet having the lens anywhere within a foot of him caused such disruptions in the photograph... So confused... I’ll continue trying to find articles on it, and I’ll look into the ultrasound thing as well, but I’m confused as to how that would apply when a bat is quiet. I had posted this same topic in the Ecology section hoping some biologist may know about I guess a bat’s response to the environment. Maybe bats emit some kind of energy on the molecular/atomic level that disrupts light/wavelengths or particles of light/whatever that won’t allow for them to be photographed.
StringJunky Posted March 30, 2018 Posted March 30, 2018 (edited) Are you using fluorescent or LED lighting? If so the the problem is Pulse Width Modulation (PWM) of the light source and the scanning nature of the camera's light sensor. Basically, The lights are flashing on and off faster than your eyes can see but the camera sensor can pick up that flashing during the course of a single exposure . For reasons I don't know, this banding problem shows up in lowlight close-up pictures. The solution is to play with the shutter timing or use a light source that has no PWM, that is continuous in its output. Edited March 30, 2018 by StringJunky
tmx3 Posted March 30, 2018 Author Posted March 30, 2018 Just now, StringJunky said: Are you using fluorescent or LED lighting? If so the the problem is Pulse Width Modulation (PWM) of the light source and the scanning nature of the camera's light sensor. Basically, The lights are flashing on and off faster than your eyes can see but the camera sensor can pick up that flashing during the course of a single exposure . For reasons I don't know, this problem shows up in low light close-up pictures. The solution is to play with the shutter timing or use a light source that has no PWM, that is continuous in its output. iPhone 4 was used. I didn’t have the light on the phone’s camera to flash when the picture was taken. The only light on in my room was my lamplight. Does this help, or? I can look at the package but I don’t think it’s LED...?
StringJunky Posted March 30, 2018 Posted March 30, 2018 1 minute ago, tmx3 said: iPhone 4 was used. I didn’t have the light on the phone’s camera to flash when the picture was taken. The only light on in my room was my lamplight. Does this help, or? I can look at the package but I don’t think it’s LED...? Is it an incandescent lamp?
tmx3 Posted March 30, 2018 Author Posted March 30, 2018 1 minute ago, StringJunky said: Is it an incandescent lamp? Uhm... do the photos help?
Strange Posted March 30, 2018 Posted March 30, 2018 7 minutes ago, tmx3 said: I meant to add, the bat wasn’t screeching when the shots were taken. He was quiet. Do you have a bat detector? (Or really good hearing? ) 3 minutes ago, StringJunky said: Is it an incandescent lamp? Good question. The ultrasound could affect the bulb causing a change in brightness captured as the image is scanned by the sensor.
tmx3 Posted March 30, 2018 Author Posted March 30, 2018 1 minute ago, Strange said: Do you have a bat detector? (Or really good hearing? ) Well! When he screeched, I heard him! But he stopped so...
Strange Posted March 30, 2018 Posted March 30, 2018 3 minutes ago, tmx3 said: Uhm... do the photos help? So its a "yes".
StringJunky Posted March 30, 2018 Posted March 30, 2018 There's some sort of asynchronous modulation going on with the sensor and something somewhere. The lamp appears to be a continuous source.
tmx3 Posted March 30, 2018 Author Posted March 30, 2018 1 minute ago, StringJunky said: There's some sort of asynchronous modulation going on with the sensor and something somewhere. The lamp appears to be a continuous source. Why does this sound so scary 1 minute ago, StringJunky said: There's some sort of asynchronous modulation going on with the sensor and something somewhere. The lamp appears to be a continuous source. I’m thinking that it’s the bit itself. It has to be emitting some kind of energy because the photos had dark bars in them only when the lens was close enough to it... Am I in the right forum??
Strange Posted March 30, 2018 Posted March 30, 2018 4 minutes ago, tmx3 said: I’m thinking that it’s the bit itself. It has to be emitting some kind of energy because the photos had dark bars in them only when the lens was close enough to it... I am fairly certain that the "energy" is ultrasound. Again, when you said it was "quiet", how do you know that? (You do realise that you cannot hear bats?) 4 minutes ago, tmx3 said: Am I in the right forum?? Arguably "Physics" might have been better, but it doesn't matter.
Bender Posted March 30, 2018 Posted March 30, 2018 7 minutes ago, tmx3 said: Well! When he screeched, I heard him! But he stopped so... You can't hear the ultrasound a bat uses for navigation. The screeching you did hear must have been some other sound bats make. Possibly, the ultrasound hit the resonance frequency in some component of your camera.
tmx3 Posted March 30, 2018 Author Posted March 30, 2018 Just now, Strange said: I am fairly certain that the "energy" is ultrasound. Again, when you said it was "quiet", how do you know that? (You do realise that you cannot hear bats?) He was screeching, I did hear him... Maybe he was a different kind of bat, I don’t know, but I heard him loud and clear when he was screeching at some times. Just now, Bender said: You can't hear the ultrasound a bat uses for navigation. The screeching you did hear must have been some other sound bats make. Possibly, the ultrasound hit the resonance frequency in some component of your camera. Oh...but how does ultrasound distupt light waves? It works like that?? Sound waves disrupt light waves? Am I on the right track here?
Strange Posted March 30, 2018 Posted March 30, 2018 Just now, tmx3 said: He was screeching, I did hear him... Maybe he was a different kind of bat, I don’t know, but I heard him loud and clear when he was screeching at some times. What Bender said. It was almost certainly generating ultrasound all the time. That is almost certainly what was affecting the camera. (Some cameras might use ultrasound to assist focusing, maybe?)
StringJunky Posted March 30, 2018 Posted March 30, 2018 5 minutes ago, tmx3 said: Why does this sound so scary I’m thinking that it’s the bit itself. It has to be emitting some kind of energy because the photos had dark bars in them only when the lens was close enough to it... Am I in the right forum?? Does it sound a bit technical? All I'm saying with 'asynchronous modulation' is that the timings of the two sources are different. This is definitely a phenomenon specific to digital cameras
tmx3 Posted March 30, 2018 Author Posted March 30, 2018 14 minutes ago, StringJunky said: Does it sound a bit technical? All I'm saying with 'asynchronous modulation' is that the timings of the two sources are different. This is definitely a phenomenon specific to digital cameras Which sources? 15 minutes ago, Strange said: What Bender said. It was almost certainly generating ultrasound all the time. That is almost certainly what was affecting the camera. (Some cameras might use ultrasound to assist focusing, maybe?) Sound affects light? Aren’t the two supposed to be independent of one another? How can one disrupt the other?
StringJunky Posted March 30, 2018 Posted March 30, 2018 (edited) 8 minutes ago, tmx3 said: Which sources? The camera's sensor, which is writing line-by-line, and the bulb, which I have just found out is flashing at twice the line frequency; 120Hz. Here's a video of that happening: Edited March 30, 2018 by StringJunky
Strange Posted March 30, 2018 Posted March 30, 2018 8 minutes ago, tmx3 said: Sound affects light? Aren’t the two supposed to be independent of one another? How can one disrupt the other? There is a possible mechanical affect: the ultrasound could vibrate the filament and hence modulate the brightness.
tmx3 Posted March 30, 2018 Author Posted March 30, 2018 3 minutes ago, StringJunky said: The camera's sensor, which is writing line-by-line, and the bulb, which I have just found out is flashing at twice the line frequency; 120Hz. Here's a video of that happening: Lol I loved the background music though it made me feel twice as dumb. Watched it the whole way through!
Strange Posted March 30, 2018 Posted March 30, 2018 2 minutes ago, StringJunky said: The camera's sensor which is writing line-by-line and the bulb, which I have just found out is flashing at twice the line frequency; 120Hz. Good point. We don't know it is anything to do with the bat! Although, I have never noticed strobing effects from incandescent bobs (and I would have thought the camera would have been designed not to be affected by that).
tmx3 Posted March 30, 2018 Author Posted March 30, 2018 3 minutes ago, Strange said: There is a possible mechanical affect: the ultrasound could vibrate the filament and hence modulate the brightness. How does ultrasound travel through an iPhone’s lens to disturb the filament? So confused. I get the whole particles moving past one another whatever is going on. I don’t understand how ultrasound could affect a photograph so much so as to create those bars. Disturbed the filament? Then shouldn’t there be a crackly image instead of straight bars???
StringJunky Posted March 30, 2018 Posted March 30, 2018 1 minute ago, Strange said: Good point. We don't know it is anything to do with the bat! Although, I have never noticed strobing effects from incandescent bobs (and I would have thought the camera would have been designed not to be affected by that). It's just a line of enquiry, like yours, which is perfectly feasible as well, from what I can see.
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