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Cops are now blinding the camera when you record them. Is there any way to prevent the camera from getting blinded? I've read about astronomers that block/filter out the sun light of stars to find planets. Can it be applied to flashlights too somehow? I have a vague memory of a special lenses that are used for welding, can it be used for flashlights?

The simplest way would be to have two cameras one meter apart on a mount but that's expensive and will not work if two cops decide to act corrupt and blind both cameras.

Tetsujin
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Dari_we
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    Back in the day in saucy magazines there were ads for a device that was essentially a lens hood with a 45° mirror and a side opening in it, so that you could shoot girls on the beach while seemingly aiming the camera at the sea. These things need to be revived. – xenoid Aug 21 '21 at 17:28
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    What kind of a camera are we talking about here? A DSLR with a telephoto lens or a cellphone? – Ilmari Karonen Aug 21 '21 at 19:51
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    @IlmariKaronen Currently only a phone camera. I was hoping there was an advanced DSLR camera that could handle this issue. – Dari_we Aug 21 '21 at 22:01
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    A way to prevent this is by supporting legislation in your country against that! – Rafael Aug 21 '21 at 22:59
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    @Rafael Legislation against police shining a flashlight at someone? – chrylis -cautiouslyoptimistic- Aug 21 '21 at 23:27
  • I was reading about laser, not a flashlight. Nvm. – Rafael Aug 22 '21 at 01:56
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    @chrylis-cautiouslyoptimistic- - you would have a fair case in court for them intentionally disrupting the recording of evidence at an incident in progress. The very act implies they have something to hide. – Tetsujin Aug 22 '21 at 06:04
  • I feel like I remember webcams (and software) selectively dimming light sources 10+ years ago... - However depending on the amount of lens flare, this might be useless... A traditional camera might not be ideal in this case as they are supposed to capture a consistent representation of reality (within the limits of manufacturer tuning). - Maybe a webcam (with associated software) or a surveillance camera (focused on maximum visibility) would be a better choice.... – DetlevCM Aug 22 '21 at 07:33
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    BTW, there is a well-known rich person with a large motor yacht that has been documented to have a powerful laser onboard. He has his crew shine it into the eyes and cameras of media photographers and paparazzi to blind them / make it dangerous to take photos of the yacht and people onboard. I have much respect for legitimate media photographers, and disdain for paparazzi, but in either case, it's a horrible thing to do to another human. – End Anti-Semitic Hate Aug 22 '21 at 23:46
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    If law enforcement is doing nothing wrong, why are they trying to prevent people from recording their actions? The innocent often want to be recorded to protect themselves, and the guilty always want to prevent any recording as they know what they are doing is wrong. Any law enforcement officer that tries to prevent legal recording needs to be expelled. Exceptions, like undercover officers, exist, but that's likely not the situation being discussed by the OP. – End Anti-Semitic Hate Aug 22 '21 at 23:52
  • @chrylis-cautiouslyoptimistic- Legislation against law enforcement trying to prevent their actions being recorded, obviously. – user253751 Aug 23 '21 at 08:49
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    here's a silly suggestion: bring more cameras than they have flashlights. – user253751 Aug 23 '21 at 08:49
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    I feel like the solution here is not about magically blocking very bright light sources while recording around them, but rather a different human approach to the recording. Who is being stopped by these "cops" and why? How are they presenting to the police officers that the interaction is being recorded? Are the police officers being reported for blocking their actions being recorded? What's the outcome of that? I feel like there is much more to the backstory here. – osullic Aug 23 '21 at 10:56

8 Answers8

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There's not much you can do to prevent a bright light pointed at your camera from causing lens flare that obscures the scene. But there are some things that can sometimes help.

The main thing to do is simply try to prevent the light from getting into the camera in the first place:

  • If you're shooting with a long lens, make sure to use a good lens hood. It won't stop bright lights in the scene you're shooting from blinding your camera, but it can prevent someone outside the scene from interfering with your photography. And in some cases you may be able to turn your camera away from the bright light and still at least capture what's happening nearby.

  • If you don't have a lens hood (e.g. you're shooting with a cell phone), just putting your hand (or a piece of paper, or whatever) between the light and the camera to shade it can help a lot.

  • Even if the light source is inside the scene you're shooting (and you can't or don't want to turn the camera away from it), just blocking it e.g. with your fingertip can eliminate or at least dramatically reduce the flaring. This is one of the rare cases where you may want your finger in the picture!

  • Of course, if there happens to be a convenient signpost or other obstacle that you can maneuver to be between the light and your camera, that can work even better than your finger. I've used this technique myself e.g. to shoot halos and other atmospheric phenomena near the sun, as in this example image from an earlier answer where I used a pedestrian crossing sign to block the sun:

    Example image with pedestrian crossing sign blocking the sun

Ilmari Karonen
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Yes there is.

The way is to use manual exposure adjusted for the shooting conditions. You can determine the exposure parameters for example by selecting a certain aperture and exposure time in manual mode with auto-ISO, aim at some direction where there is no bright light source, then half-press the shutter button, then see if the selected ISO is acceptable. If the ISO is acceptable, select it manually. If the ISO is not acceptable, then you need to either adjust the aperture and/or exposure time and retry.

Of course the bright light source causes flaring at the lens but at least it doesn't blind the entire camera.

juhist
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  • An effective suggestion. I don't know why you were marked down. +1 – user10216038 Aug 21 '21 at 17:53
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    I don't get the logic behind this. Set ISO for the dark & the flashlight will flare it out completely. Set it for the light & the rest is going to be just black. There's got to be 10 stops or more between the two. – Tetsujin Aug 21 '21 at 18:05
  • Well, it may depend on the brightness of the scene and the power of the flashlight. My understanding is that most bright light sources even at night cause only flaring instead of blinding the entire camera. However, I have no experience with police flashlights so I don't know how bright a police flashlight is. Usually flashlights are designed to make the area where you point them acceptably bright, perhaps a bit brighter than streetlights make it. A streetlight doesn't blind the camera but causes flaring. Of course if the flashlight is very near the camera, then it may be too bright. – juhist Aug 21 '21 at 19:02
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    I just tested this with a cellphone camera (Samsung S8+), a dimly lit room and a bike headlamp. Doesn't work. Most (basically all) of the interference comes from flaring, not from the exposure metering getting confused. (In fact, the automatic exposure seemed pretty spot on in all tests, or at least as good as it could possibly be under the circumstances.) I guess an older camera with poorer exposure metering might benefit from this. – Ilmari Karonen Aug 21 '21 at 20:02
  • @Tetsujin - The same issue occurs taking a sunset shot. Override the automatics to expose for the darker scenery. The sun and sky will be blown out but you can still photograph the darker mountains or beach. – user10216038 Aug 21 '21 at 20:02
  • @Ilmari Karonen - I took your suggestion and performed the same test. A darkened room with a cell phone camera looking straight into an 900 lumen flashlight 10 feet away. Manually selecting for the darker surroundings allowed a successful shot. Yes there was significant lens flare, but that's a pretty extreme condition. – user10216038 Aug 21 '21 at 20:19
  • @IlmariKaronen: When you say "doesn't work", do you mean you couldn't make out anything at all that was going on? You're obviously not going to recover a clean shot you'd want to use, but if you can still see anything, that's better than nothing. And if you can still make out enough to tell who's doing what to whom, (perhaps even as usable legal evidence), that's sufficient for videos of police officers. – Peter Cordes Aug 22 '21 at 02:14
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    @PeterCordes: I mean that I could never get a significantly better shot using manual exposure in "pro" mode (and/or exposure adjustment in normal photo mode) than by just shooting normally with auto exposure and ±0 adjustment. If the light was off to the side, the automatic metering seemed to mostly ignore it; if it was right in the middle and pointed straight at the camera, there was so much flaring that no amount of exposure adjustment could produce a useful image anyway. In any case, adjusting exposure up also brightened the flare, often making the image worse, not better. – Ilmari Karonen Aug 22 '21 at 09:38
  • Anyway, I'm not saying that this trick could never be useful. For some cameras, under some lighting conditions, manual exposure can probably help. But it's not going to fix the biggest issue, which is lens flare. – Ilmari Karonen Aug 22 '21 at 09:40
  • There are potentially several things going on depending on the type of camera, lens, and sensor we're talking about. 1) get a good lens, lenstip.com has reviews with images showing flare characteristics 2) don't use a ccd sensor, they bleed light between pixels and 3) this post, make sure exposure is correct. You guys saying the exposure isn't the issue for you... I suspect your lenses have very poor coatings... cell phone lenses are not exactly top notch and often covered in oils from hands. The size of the aperture may also be an issue as the beam covers your entire lens opening. – ttbek Aug 23 '21 at 12:59
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Depending on the flashlight, an infrared camera tuned for near infrared frequencies is likely to work.

There are many vendors of infrared conversion services, some infrared converted cameras in the used market, and YouTube videos for do it yourself conversion of various camera models.

Flashlights are typically optimized for visible frequencies.

Bob Macaroni McStevens
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To minimize flare:

  • Keep the front of your lens clean at all times, no pocket dust or finger prints. Keep a lens-cleaning supplies (at least a lens cloth) handy and use it regularly.
  • In a pinch or emergency, wipe the lens with the cleanest bit of clothing you can come up with, like a shirt tail.

Possibility of a filter?

Many flashlights are now white light LEDs, which have a peculiar spectrum due to the way they the light is produced; a blue LED and a yellow semi-transparent phosphor. The spectrum drops at extreme blue and red, but so does the sensitivity of the color filters on the camera's sensor.

@BobMacaroniMcStevens's answer mentions near IR which is a great idea of you can find the right sensor that doesn't have a NIR blocking filter built in. That would not be any help for a tungsten-halogen light which would be extremely bright in NIR, but it would probably work well to block LED light.

The problem though is that there won't be any other NIR light to illuminate the scene unless you are lucky, and flashes on camera phones are also white light LEDs so will be of no help. Same problem for LED street lights.

Perhaps the minimum around 500 nm is a third place for a filter, but again if white light LEDs are what's illuminating the scene, it provides no benefit.

Keep your cell phone lens very clean is your best bet, it can make a huge difference.

white LED spectrum

Source

uhoh
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    So, carry a big incandescent flashlight yourself, to illuminate the scene in IR? Preferably one that doesn't look like it could double as a truncheon (especially a long black C or D-cell Maglite); you don't want to look "armed" if the police are already harassing you while you try to record. – Peter Cordes Aug 22 '21 at 02:18
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    @PeterCordes Good idea! One could modify it with a filter to minimize visible light as well, so it would not present a challenge to anybody else's vision or photography. It would probably be somewhat reddish, but could be completely dark if one was using pure NIR sensitivity. – uhoh Aug 22 '21 at 02:24
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    @PeterCordes just use IR LEDs like the ones used in NightShot-capable cameras. – Ruslan Aug 23 '21 at 11:37
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Short answer is no, not really. Any filter that blocks the stronger (near) full spectrum of the flashlight will also block the weaker light of the scene/background.

Astro filters are typically color filters only affecting small portions of visible light.

Steven Kersting
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Double down. Use your own high-intensity lighting to flood the scene with light.

A flashlight is bright at night, but shining a flashlight into the camera in full daylight sun, for example, won't really do much at all because the camera is exposing for the enormous abundance of light in the scene and the relative contribution from the flashlight is correspondingly diminished. This is increasing the signal (scene) to noise (flashlight) ratio by boosting the amount of usable illumination in the scene.

A couple of aftermarket automotive LED HID headlights with a 12V battery pack would work. Of course, now you're engaging in a flashlight arms race with the police, so...

J...
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Depending on how the flashlight is held, a half ND filter might improve the situation.

Something like this:

HalfND

Half ND Filter

Covering the lower half of the shot with the ND part, might allow you to get the face/upper body of the cop, in case they are holding the flashlight at waist height. (pretty situational, though)

(I would also recommend a lens hood anyway)

Redy000
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If a flashlight is aimed directly at your camera at night, this will create high contrast in the scene between the flashlight and its flare, and the subject which is in the dark.

You can fix that by reducing the intensity of the light, but you can also fix it from the other end, by increasing the amount of light on the subject. During the day, this is usually done with fill-in flash or reflectors.

Therefore, a practical solution is to wear a white t-shirt, which will reflect the light from the flashlight towards the subject of the picture. This will not fix the lens flare, but it will light the subject better, and it is plausibly deniable and inconspicuous.

However that requires you to be perhaps closer than you would like.

The other solution is to have friends, which means having more cameras (and witnesses) than there are flashlights.

You could also play with the camera settings to decrease contrast, to make sure dark areas are not pure black but still contain usable detail that can be recovered via post processing. Perhaps use night mode, or manual mode. Using the highest quality setting and lowest compression will help.

Another thing you could do is simply hide the phone.

bobflux
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