Picture of See Infrared LED Light with an iPhone 4...
OK, I admit that this is a short and hopefully sweet Instructable, but it stumped me until just now so, I thought I'd share.

Back in the old days, you could use the camera in your PDA or cell phone to "see" the infrared light that was coming out of a TV remote controller or similar device.  I actually did just this when I worked on the MythBusters show when we did the "Beating Police Radar and Lidar" story...you saw my hand holding my old Palm Zire 72 and through the camera's viewfinder, you could see that the infrared LEDs on the license plate frame were actually working and producing light.  The studio cameras couldn't see the IR light because they have IR filters.  But the cheap camera in the Palm could see the IR light quite well.

Since the iPhone 4 came out, I've been bugged that I was unable to see IR light anymore, and I was very disappointed to learn that the iPhone 4 added an infrared filter to its camera.  Although it makes photography look much better, it was no longer useful to me as an IR troubleshooting tool.  That explained why I couldn't see IR sources anymore, and I had to borrow my 11 year old son's hand-me-down iPhone 3GS to diagnose questionable IR sources.

I considered buying a cheap VGA resolution keychain digital camera with a viewfinder, but then that would be one more thing to carry around with me.

Today I was trying to use my TV-Be-Gone (thanks, Mitch) in the Delta Skyclub at the Washington DC airport to turn off a TV with loud chattering new people on it.  My TV-Be-Gone wasn't working to turn off the TV, so I decided to try to see if it was working or not.  I fired up my iPhone 4 and opened the camera app, pointed the camera at the TV-Be-Gone's IR LED, and pressed the button on the TV-Be-Gone.  I didn't see any light from the IR LED in the iPhone's viewfinder.

Then it occurred to me to try the forward-facing FaceTim camera.  I clicked the camera switch button on the iPhone screen and pointed the FaceTime camera at th still-blinking TV-Be-Gone IR LED, and sure enough I was able to see the light coming out of the IR LED!

The following steps will reiterate the above steps, and will show you how to see infrared light with your standard iPhone 4, and possibly other smartphones and tablets too.
johnip45 days ago
It works on my iPad Air 2 FaceTime camera
Light_Lab8 months ago

Here's are some odd results: My old iPhone 4 picks up IR like a search light - both cameras. My iPhone 4S only the front camera, my iPod 5 touch very slightly on the front camera only. My iPad Air nothing on both.

BenjaminW19 months ago

Isn't this a "frame rate" issue? Maybe not issue, but the frame rate on newer iphones is higher.. We use this tool at work a lot, I have an S4

FredS29 months ago

Absolutely useful piece of info.

PaulO39 months ago

Thanks! Simple but *exactly* what I needed. I am trying to test a photo-interupter used on a circuit board (on a driveway gate opener of all things), I knew about the old-cell-phone-sees infrared trick, but of course the main camera on my iPhone 6 and every other digital camera I had handy had an IR filter and couldn't see IR when tested with a TV remote. Didn't occur to me to try the front camera, but it works perfectly on the iPhone 6 as well! On to testing my gate opener...

andyhess1 year ago

I have a slightly different story. I have a Samsung Galaxy III, on the lens that faces away from the screen, I can see dim purple dots blinking (that I can't see with my eyes) on my tv remote, but the rear facing lens (the lower quality one) I see a bright bluish-white light. So a not very dense filter on one and no filter on the other.
gomanjorge3 years ago
I can confirm that this works with the iPhone 4S too.
Works on my iphone 5 as well. Facetime camera, not the forward facing camera. Very cool.

TechShopJim (author)  gomanjorge3 years ago

Hi GomanJorge...

Excellent...thanks! Actually that's what I have. I should have specified.

jshireling2 years ago
Cool, thanks!!
duh!!! any phone or camera... genius...
doesnt work with iphone 5. either camera.... :(
c0deater3 years ago
i can also confirm this works on both cameras of the motorola atrix 4g,.
As someone else stated, most digital cameras are immediately IR sensitive.. Even webcams on PC's, Laptops.. The majority of heat detector cameras used by the fire service, are based on a simple CCD array chip, as someone else noted, without a IR filter. I've done this to test IR remotes, IR-Xfer modules for laptops, PDA's, Even outdoor security cameras which have the lenses surrounded with IR-LED's.. (you should see how they look when driving by a place you know has a camera.. the whole doorway lights up!) I can't remember where I saw it, but someone had a hack, which required scraping the IR filter off the lens of one of the 'one-time-use' digital camcorders from CVS. (Pure Digital, of which the Kodak, & FliP cameras are based.) A wee bit distructive, if you're not careful.. But, even with the IR filter in place, they're still pretty sensitive.
Typically CCD cameras are sensitive only up to ~1000nm or so. This means they are really near infra red (NIR) cameras. As such they are not very sensitive to heat. Heat detector cameras are true infrared cameras and sensitive to much longer wave lengths. Part of this is due to special lens materials used (eg Indium) which is much more transparent to IR than glass and plastic.
drdan1523 years ago
McMchriis3 years ago
In all Of the Digital cameras we can see that!!!
makendo3 years ago
Ha, neat! Works with both cameras on the iPad2.
TechShopJim (author)  makendo3 years ago
Hi Makendo...

I wonder if the iPad 3 has an IR filter on its primary camera. I'll bet it does.