See Infrared LED Light With an IPhone 4...

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About: I'm the Founder and Chairman of TechShop.

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.

Step 1: Try Using the Rear-Facing Camera to See Light From an Infrared LED

On your iphone, start the Camera app, and point the camera at the LED on your favorite TV remote control.

As you look at the iPhone screen, press some buttons on the remote.

Although the remote is probably putting out a bright infrared light beam, you cannot see it with your eye because your eye is not sensitive to light in the frequency of infrared (around 940nm for a remote control).

Your iPhone's main camera cannot see infrared light, because Apple added a filter over the lens that blocks out infrared light, so the infrared light cannot be seen on the screen.

Step 2: Now Try Using the Front-Facing FaceTime Camera to See Light From an Infrared LED

Now press the "switch cameras" icon in the upper right corner of the iPhone's Camera app so that the FaceTime camera's view is being displayed on the screen.  You will probably see yourself on the screen.

Now point the FaceTime camera at the LED end of your TV remote control and press a button on the remote.

Your eye can't see the IR light, but now you will see the IR light appear in the viewfinder as a bright white light.

It turns out that the FaceTime camera on an iPhone 4 does NOT have IR filtering on it!  Yay!

I hope this is useful to even just one person in the Instructables community.  Please use this information for good, and not for evil.

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27 Discussions

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ardnon

2 months ago

Works on iPhone SE with the front facing (selfie) camera

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Great find Jim, thanks for sharing. I was just trying to test a remote with my iPhone 5. I tried a known good remote as a check and couldn't see it the LED lighting. I googled to see if there was a way to make it work, when I came across this Instructable.

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David MatthewM

2 years ago

I made myself a handy infrared flashlight from a battery-powered (3 x 1.5 V) reading light by unsoldering the white-light LED and soldering an infrared LED in its place. I then turned the room lights out, aimed the "flashlight" right at my face, and was rewarded by the sight of my right eye in the selfie cam image of my iPhone 4S- rendered in infrared!

Maybe a sufficiently bright IR lamp would let me walk around in the dark using my iPhone, but how do you do that with a front-facing camera?

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pumpdatbassDavid MatthewM

Reply 1 year ago

you really cant. if you want to use your phone as an IR NV headset, buy a cheap galaxy phone. both front and rear caneras sense IR

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JustinH177

2 years ago

Wow! My iPhone 6 blocks the IR on the main camera, but sure enough the front-facing camera can see the IR light. Cool!

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TechShopJimJohn_Singleton_

Reply 2 years ago


Hi John_Singleton_ ...

That's weird.

I just upgraded from an iPhone 4s after many years to a 6s Plus, and both front and rear cameras are able to see the IR on my remote (unline my 4s)!

I guess it just depends on how much IR filtering each iPhone model was given.

Can you see the IR remote light on your "selfie" facing camera?

Thanks!

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MattP33

3 years ago

Would the intensity of an IR light source make a difference on a IR filtered cell phone camera?
Ex. Hitting it with an IR floodlight used to assist night vision ?

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johnip4

3 years ago

It works on my iPad Air 2 FaceTime camera

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Light_Lab

4 years ago on Introduction

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.

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BenjaminW1

4 years ago on Introduction

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

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PaulO3

4 years ago on Step 1

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...

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andyhess

5 years ago on Step 2


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.

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andyrakgomanjorge

Reply 5 years ago on Step 2

Works on my iphone 5 as well. Facetime camera, not the forward facing camera. Very cool.

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TechShopJimgomanjorge

Reply 6 years ago on Step 2


Hi GomanJorge...

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

Thanks!