is there any difference between blue and red lens's on cameras?

[Guest mikeeey]

most camera phones's lens were red for a while, and now some newer phones im seeing have blue lens's

the 8525 i think has a blue one.

are these better? do they let in more light for better pictures? that would annoy me how a lot of the htc phones weren't good in the dark.

im interested in knowing the difference between these 2 lens's

[Guest Monolithix (MVP)]

Right, (as we've just been discussing!), after a bit of revision over some course notes i have from a year or so back, this is my answer, be ready because it gets a bit physics-y!

I'd imagine the difference in colour makes very little difference. The reason the lenses appear that colour, red or blue (violet, in fact), is due to a special coating applied to the lens to allow as much light as possible through. The glass lens has a different density and therefore a different impedance to light than the air, so on its own reflects a portion back out due to that "resistance" to the incident light. This makes sense, if you look at a sheet of window glass you can see a faint reflection. Of course any photographer will tell you that you want to get as much light as possible through to the sensor (or film!), this is where the coating comes in. With the implementation of some simple mathematics it is possible to show that by adding a thin layer of material of a specific impedance "cancels" the difference between the glass and air, and "matches" them together, allowing the light to pass straight through with no reflection, and therefore more gets through to the sensor!

However there is a slight catch, the coating can only match the impedance of a single wavelength, so as you move away from that wavelength more light is reflected. Fortunately the wavelength bandwidth which the human eye is capable of seeing is quite narrow so all you see is a bit of red or violet, right at the boundries of the visible spectrum!

Phew, and relax...appologies to any electromagnetism experts out there if some of the points are a little vague or inaccurate, i'm not a physisist!

(Further reading here, if you're that interested :rolleyes: http://personal.ph.surrey.ac.uk/~phs3sd/pd...er_version.pdf)

[Guest mikeeey]

Right, (as we've just been discussing!), after a bit of revision over some course notes i have from a year or so back, this is my answer, be ready because it gets a bit physics-y!

I'd imagine the difference in colour makes very little difference. The reason the lenses appear that colour, red or blue (violet, in fact), is due to a special coating applied to the lens to allow as much light as possible through. The glass lens has a different density and therefore a different impedance to light than the air, so on its own reflects a portion back out due to that "resistance" to the incident light. This makes sense, if you look at a sheet of window glass you can see a faint reflection. Of course any photographer will tell you that you want to get as much light as possible through to the sensor (or film!), this is where the coating comes in. With the implementation of some simple mathematics it is possible to show that by adding a thin layer of material of a specific impedance "cancels" the difference between the glass and air, and "matches" them together, allowing the light to pass straight through with no reflection, and therefore more gets through to the sensor!

However there is a slight catch, the coating can only match the impedance of a single wavelength, so as you move away from that wavelength more light is reflected. Fortunately the wavelength bandwidth which the human eye is capable of seeing is quite narrow so all you see is a bit of red or violet, right at the boundries of the visible spectrum!

Phew, and relax...appologies to any electromagnetism experts out there if some of the points are a little vague or inaccurate, i'm not a physisist!

(Further reading here, if you're that interested :rolleyes: http://personal.ph.surrey.ac.uk/~phs3sd/pd...er_version.pdf)

lol confusing, but after reading it a few times i think i get it.

thanks for taking the time to answer :P

[Guest The Doctor]

Right, (as we've just been discussing!), after a bit of revision over some course notes i have from a year or so back, this is my answer, be ready because it gets a bit physics-y!

I'd imagine the difference in colour makes very little difference. The reason the lenses appear that colour, red or blue (violet, in fact), is due to a special coating applied to the lens to allow as much light as possible through. The glass lens has a different density and therefore a different impedance to light than the air, so on its own reflects a portion back out due to that "resistance" to the incident light. This makes sense, if you look at a sheet of window glass you can see a faint reflection. Of course any photographer will tell you that you want to get as much light as possible through to the sensor (or film!), this is where the coating comes in. With the implementation of some simple mathematics it is possible to show that by adding a thin layer of material of a specific impedance "cancels" the difference between the glass and air, and "matches" them together, allowing the light to pass straight through with no reflection, and therefore more gets through to the sensor!

However there is a slight catch, the coating can only match the impedance of a single wavelength, so as you move away from that wavelength more light is reflected. Fortunately the wavelength bandwidth which the human eye is capable of seeing is quite narrow so all you see is a bit of red or violet, right at the boundries of the visible spectrum!

Phew, and relax...appologies to any electromagnetism experts out there if some of the points are a little vague or inaccurate, i'm not a physisist!

(Further reading here, if you're that interested :rolleyes: http://personal.ph.surrey.ac.uk/~phs3sd/pd...er_version.pdf)

Sounds about right :D

Bit of clarification, if the coating is 'geared' more towards the red end of the spectrum, the lens will look blue. If its 'geared' to the blue end, it will look red :P So really, on a phone camera, the colour of the coating won't make much difference to the overall image quality :D

Just for the record, that coating on the lens on a Hermes camera is about 160nm thick (yes thats 0.000000160 metres)

Phil

[Guest Monolithix (MVP)]

Yus i did consider going into more detail but my brain was aching from all that physicsness! Those notes are actually quite interesting reading if you're into that kinda thing!

Another interesting (if you like...) point to note is that most digital cameras are sensitive beyond our visible bandwidth, try pointing a tv remote at your camera and pressing a button :rolleyes:

[Guest The Doctor]

Yus i did consider going into more detail but my brain was aching from all that physicsness! Those notes are actually quite interesting reading if you're into that kinda thing!

Another interesting (if you like...) point to note is that most digital cameras are sensitive beyond our visible bandwidth, try pointing a tv remote at your camera and pressing a button :rolleyes:

Hehe, works better if you take your camera apart and remove the IR filter :P

Coca cola appears transparent! :D

Phil

[Guest mikeeey]

Yus i did consider going into more detail but my brain was aching from all that physicsness! Those notes are actually quite interesting reading if you're into that kinda thing!

Another interesting (if you like...) point to note is that most digital cameras are sensitive beyond our visible bandwidth, try pointing a tv remote at your camera and pressing a button :rolleyes:

whoa i can see the infared! it worked on my phone!

so the camera converts it into a color we can see? but in reality it doesnt look that color, its some unkown color we cant see?

imagine that, trying to think of a different color... its impossible to think of. makes ur brain hurt lol

and here's a movie i uploaded of it in the dark.

infared_movie.wmv

Edited June 4, 2007 by mikeeey

[Guest James]

I remember trying that to compare the IR transmitter levels of my original SPV Vs a TV Remote back in the 'old' days (jan-feb 2003) when everyone was asking for a remote control application for the SPV! :rolleyes:

ah memories!

[Guest James]

Hehe, works better if you take your camera apart and remove the IR filter :rolleyes:

Coca cola appears transparent! :P

Phil

That realy true!!!???

what a party trick!..

[Guest The Doctor]

That realy true!!!???

what a party trick!..

The trick is removing the IR filter without buggering the optics in the camera or scratching the lens :rolleyes:

Phil

[Guest mikeeey]

Hehe, works better if you take your camera apart and remove the IR filter :rolleyes:

Coca cola appears transparent! :P

Phil

what part is the IR filter? i dont think i wanna sacrifice my camera so i can see some Coca cola appear transparent lol. now when u say transparent what do u mean? on a computer that would be inverted color. and do u mean the coca cola liquid itself? or the can?

[Guest The Doctor]

what part is the IR filter? i dont think i wanna sacrifice my camera so i can see some Coca cola appear transparent lol. now when u say transparent what do u mean? on a computer that would be inverted color. and do u mean the coca cola liquid itself? or the can?

As in the liquid, the IR filter is the piece of red/green plastic at the back of the lens assembly, It looks green from one angle and red from another...

Phil

[Guest mikeeey]

As in the liquid, the IR filter is the piece of red/green plastic at the back of the lens assembly, It looks green from one angle and red from another...

Phil

and without it will it look like the inverted affect on coolcamera? or different?

btw i uploaded a video of the infared in the dark on the same post as the picture. just having some fun with this lol

also it looks like the infared is just like a real light. it shines on walls and stuff too. i wish i had a bigger light so i could see in the dark lol.

Edited June 4, 2007 by mikeeey

[Guest The Doctor]

also it looks like the infared is just like a real light. it shines on walls and stuff too. i wish i had a bigger light so i could see in the dark lol.

Thats pretty much what it'll look like if you remove the IR filter, except it'll be brighter. Works in perfect 'darkness' so long as you have an IR light source, the room will look pitch black to you, but with the IR sensitive camera, it will look bright...

Phil

[Guest darkswitch]

Oh! So thats the thing you told me not to pull of on my C600 when I was removing the camera incase I break it :rolleyes:

Too late!

[Guest mikeeey]

Thats pretty much what it'll look like if you remove the IR filter, except it'll be brighter. Works in perfect 'darkness' so long as you have an IR light source, the room will look pitch black to you, but with the IR sensitive camera, it will look bright...

Phil

cool, but how bright of an IR light would i need? also how would this effect trying to take normal pictures?

[Guest The Doctor]

Oh! So thats the thing you told me not to pull of on my C600 when I was removing the camera incase I break it :P

Too late!

I DID tell you not to expose the CCD to unnecessary light, IE yanking the lens assembly off it :rolleyes:.

@mikeeey, it wont affect the picture quality that much if you remove it, and you'll need about 10 IR LED's to produce any reasonable amount of IR light. More info HERE

Phil

[Guest mikeeey]

also ive found here, a video, how to turn a remote control into a infrarad light. it has to to with connecting the IR light strait to the battery and it becomes brighter.

http://images.metacafe.com/watch/458008/tu...red_flashlight/

and here's how to turn a webcam into an IR Camera.

http://www.metacafe.com/watch/385098/trans...n_infrared_cam/

this + the remote control light would be pretty bright.

i think il try the remote control thing later today if i can find a remote control to use.

ive noticed we've gone from talking about hte difference between the blue and red camera lens's (which has already been answered) to this interesting topic on IR lights. should this be moved to the off topic section? or can it still stay here since its still on the topic of cameras?

[Guest The Doctor]

also ive found here, a video, how to turn a remote control into a infrarad light. it has to to with connecting the IR light strait to the battery and it becomes brighter.

http://images.metacafe.com/watch/458008/tu...red_flashlight/

and here's how to turn a webcam into an IR Camera.

http://www.metacafe.com/watch/385098/trans...n_infrared_cam/

this + the remote control light would be pretty bright.

i think il try the remote control thing later today if i can find a remote control to use.

ive noticed we've gone from talking about hte difference between the blue and red camera lens's (which has already been answered) to this interesting topic on IR lights. should this be moved to the off topic section? or can it still stay here since its still on the topic of cameras?

Theoretically we're still discussing camera lenses :rolleyes:

Phil

[Guest mikeeey]

well monolithix id like to thank you for teaching me about the Infrared light thing cuz i have chosen to do a project on this at my school, so im really starting to learn a lot from it now. ive decided to modify a remote by turning it into a IR flashlight. im going to go to a hardware store and buy some more powerful infrared lights, and see how bright i can get this. il post some form of video or picture of it when im done.

[Guest James]

You should be a bit careful with very bright IR sources such as IR Laser diodes and very high output lamps/LED's because your eyes cant see the light they cant react to it (by lowering the amount they let in) thus very bright IR light sources can damage your eyese without you knowing it... :/

but hey! i dont think you going that bright so have fun!! and good luck with your shcool project!

[Guest mikeeey]

You should be a bit careful with very bright IR sources such as IR Laser diodes and very high output lamps/LED's because your eyes cant see the light they cant react to it (by lowering the amount they let in) thus very bright IR light sources can damage your eyese without you knowing it... :/

but hey! i dont think you going that bright so have fun!! and good luck with your shcool project!

lol ok il keep that in mind. besides, most of the time my phone will be blocking the IR light from my eyes. i will be seeing it through the camera.

[Guest Monolithix (MVP)]

Glad to have helped mikeeey, enjoy your project (i've just finished an electronics degree so its a good to share the love a bit ;p)