Google refuses to give me any relevant results :-(
Is there some way lenses can be utilised in a camera to completely block light? How about two orthogonal(?) polarising lenses? Or perhaps a combination of tinted lenses or filters?
AJ
Google refuses to give me any relevant results :-(
Is there some way lenses can be utilised in a camera to completely block light? How about two orthogonal(?) polarising lenses? Or perhaps a combination of tinted lenses or filters?
AJ
Is there some way lenses can be utilised in a camera to completely block light? How about two orthogonal(?) polarising lenses? Or perhaps a combination of tinted lenses or filters?
As SB notes, this would negate the purpose of a camera.
The only reason I could think of for doing this would be to blackout a security camera for nefarious purposes. For this, black spray paint to the lens would be quicker, easier, and cheaper.
As SB notes,
Has a reply been deleted? I thought maybe I had blocked SB or vice-verso, but I see SB replies on other threads, so....
Has a reply been deleted?
Apparently. When I posted my reply there was a reply by Switch Blayde.
Has a reply been deleted?
Yes, I deleted it. I'm surprised it was seen since I deleted it almost right away.
I asked what the camera would be used for since a camara doesn't work when there's no light. But then I realized that some kinds of cameras can work with no light, like thermal cameras. So I deleted the post not wanting to sound dumb.
But then I realized that some kinds of cameras can work with no light, like thermal cameras.
https://www.dwyeromega.com/en-us/resources/thermal-imagers
A thermal imaging camera is a device that captures infrared radiation emitted by objects and converts it into a visible image, a process that is called Thermal Imaging.
Infrared radiation is outside of the range of what is detectable by the human eye, but it is light. It is part of the same electromagnetic spectrum as visible light.
Yes, I deleted it. I'm surprised it was seen since I deleted it almost right away.
👍🏻
I'll mention that you could definitely make special "lenses" that would do this without seeming to be anything special.
The easy way would be with coatings of the type that are used on modern eyeglasses. Although the wearer can see out perfectly normally, the exterior of these lenses often fluoresces, especially in photos. For example, if you have a glare reduction coating on your glasses and take a selfie with a mobile device outside, the lens will reflect more than you would expect. I've even seen photos where it looks like the glasses are glowing blue, cyberpunk style.
You'd have to hand wave it a bit, but you could say that someone got an applicable pair of glasses, popped out the lenses, and fitted them into camera lens apparatus backwards. I doubt it would really work, but with a bit of setup it would workable.
Or you could simply buy a polarizing filter for your camera. I've got them in several sizes for different lenses.
It already exists and it uses your polarizer technique. In photography, a neutral density filter reduces the light entering the lens by a set number of stops without changing tone. Great for shooting a sunset, or achieving that cool milky effect from a long exposure of moving water. So… a variable neutral density filter is two polarizer filters fastened together, with a lever that allows one to be rotated in relation to the other. I've seen them able to turn completely opaque (to my eye anyway). Check them out on Amazon.
E
Except, you could do the exact same, much faster and much more efficiently, either by adjusting your smartphone settings OR manually adjusting them in any of a number of photo-management apps/programs. I've been doing that for what the last twenty of thirty years now (less for the smartphones, obviously).
It seems a pretty old-school technique, yet for escaping police cameras, it makes a LOT of sense.
Agree that you can simulate an ND filter in post, but I haven't been able to achieve the same effects as an ND in post processing alone. YMMV … it's possible I'm just reverting to a technique that I know will work out of impatience.
What you do is have the shutter button sensitive to the fingerprint. So when the photographer presses, the camera "clicks" but no photo is actually taken… Unless that finger's fingerprint is in the file of fingerprints stored in the camera's memory, in which case the photo is taken as usual. So for a particular photographer, maybe his (or her) index finger's fingerprint is not on file, but his (or her) middle finger's fingerprint is.
I wish you hadn't asked that because an explanation would give too much of the story away. Suffice it to say, the protagonist wants a combination of lenses that theoretically blocks all light but in some handwavium circumstances light actually appears to pass through.
AJ
In that case, by using variable strength lenses in each color, you could make some more visible than others (like red, which typically has the shortest wavelength). It's an intriguing concept, and I'm interested in how it plays out.
Build a camera with two 100% linearly polarizing elements (doable to 99%+ in modern technology). Mount one of them in a rotation ring. When the two lenses are aligned, you see the full scene (assuming the scene itself is unpolarized). Rotate the one lens 90 degrees so that the linear polarizers are crossed. You now have zero light passing through ("zero" being limited by the imperfections in the filters).
The scene caveat: the light from most natural scenes is unpolarized. The light from some scenes is highly polarized--notably glint off of water or metal and many digital displays. Those will get you different results.
If you want to test this out, get two polarized sunglass lenses (take one pair and pop the lenses out of the frame). Then look through both of the lenses and rotate one. The intensity of the light will change as a function of the rotation angle.
If you want to wade into more technical details, drop me a private message.