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Sharing the display of your smartphone can be tricky. While there are some Android devices that support HDMI Droid Meets HDMI: How (And Why) To Connect Your Android Phone To Your TV Droid Meets HDMI: How (And Why) To Connect Your Android Phone To Your TV A recent trip to a local used goods store brought me into contact with the LG Optimus 3D P920. Following some quick checks online via my usual phone, I bought the device – and soon... Read More , the best option for smartphone owners on all platforms is usually to employ some screen-mirroring software (particularly straightforward for iOS users How to Mirror the iPhone or iPad to Your TV How to Mirror the iPhone or iPad to Your TV Don't get stuck watching video or playing games on the small screen, your iPhone or iPad can also be used with larger displays. Read More ) and view the current app on a HDTV or monitor.

There is another way though, and that is to project your display. Setting your mobile device up with a digital projector is simple enough, but you also have the option of turning your phone’s screen into a projector.

Yes, you read that right. And all you’ll need is a projector lens and an old shoebox.

Step 0: The Simple Option: Buy a Kit

None of this is an original idea. Rather, it is a DIY version of Luckies’ Smartphone Projector, a cardboard flatpack system that you can build yourself.

Essentially, the device is a camera obscura – a black box with a hole in it, and illuminated image within. The camera obscura is one of the keystones of photography, the notion that an image can be projected through a small hole in a box or even room, and displayed on the opposite side, rotated 180 degrees. Without the discovery of this optical phenomenon, it is unlikely that photography and the photographic camera would have been developed.

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So, Luckies’ Smartphone Projector uses this principle, as does any projector, using a lens to rotate the image, hence righting the image so it can be viewed Electric Slide: Make Wireless Presentations Using Your Smartphone or Tablet [iOS] Electric Slide: Make Wireless Presentations Using Your Smartphone or Tablet [iOS] Read More .

Step 1: You Will Need

The great thing about the camera obscura is that you don’t need a special $80 box to recreate it; you can use an old shoebox, a tub of black paint, some adhesive putty, a suitable lens, and your smartphone.

The sort of lens you will need for this project is a biconvex lens. These can be purchased from photography shops or online from specialist retailers, Amazon or even eBay. In fact, should you have an existing projector you may be able to remove the lens and use this.

Step 2: Where Can You Find a Suitable Lens?

Lenses can be expensive, so a good option to keep the price down is to find an old cine or slide projector and remove the lens from that.

To project your smartphone display through the hole in your shoebox, you’ll need to ensure that the device is positioned at the correct distance (the optimum focal length) from the lens. To get an idea of the size of the shoebox you require, find a darkened room in the dead of night, switch your phone’s display to the maximum brightness and place it around 6 inches behind your lens, pointing both devices at a blank wall or pinned-up sheet of paper.

While the image will not be particularly bright or sharp, it should give you enough information to judge the size of the shoebox you will need.

Step 3: Getting Started: Install the Lens

Begin by placing the shoebox on one end, and determine where the lens will be fitted by using a ruler or measuring tape to find the centre of the box end. It’s a good idea to draw two lines to make a cross. Place the lens over the cross, getting it as close to centre as possible, and draw around it.

After you have cut out the shape of the lens, place it into the hole, using the adhesive putty to keep it in position. You can substitute this for duct tape later, but bear in mind that you may need putty to support the length of the lens; a small matchbox might be employed here to prop the lens in place temporarily.

Step 4: Insert Your Phone

Inside the box, place your phone, with the lock screen disabled and the brightness turned to full. While one option is to secure it in place temporarily with more of the putty, for the best results use a smartphone case that will allow the phone to “stand” on its side for viewing.

With the lid replaced, return to your darkened room and check the quality of the projected image. You should be able to focus the image by adjusting the position of the phone, moving it back and forth, making sure to secure the putty again when you’re satisfied.

Step 5: Painting

When you’re finally happy with the positioning, make some notes, take a couple of photos and even pierce a couple of holes on each side of the box so that you can find the “sweet spot” again later, after you’ve painted it.

It’s now time to paint the shoebox. Ideally you should paint inside and out, but certainly the inside needs every surface coating in black paint, preferably acrylic. Naturally you should remove the lens and your smartphone before painting; don’t replace them until the paint is bone dry.

Don’t forget to paint the inside of the lid!

Step 6: Putting it All Together

With the paint dry (you might opt for a second coat, especially if you used poster paint (a cheaper alternative to acrylic), it’s time to put everything back together. With the lens now fixed back into place, position the phone, and turn the lights down to ensure the image is being projected and is in focus.

You’ll notice something is wrong: the projected image is upside down. The solution is to turn your phone upside down, leaving the image locked. If you’re using an iPhone, all you need to do is the activate the orientation lock while in landscape view, and then flip the phone upside down. On Android, you can do this with an app such as Set Orientation, free from Google Play (and not alone in its functionality).

Step 7: Finished!

With the orientation issue fixed, you’re done. You’re the owner of a smartphone projector How I Built A Projector For My Phone How I Built A Projector For My Phone When I first saw Photojojo's DIY iPhone projector I was intrigued. The science behind it was sound in my mind, but I wondered how usable it really was. The only way to find out was... Read More , built from a shoebox, all for the cost of some black paint, adhesive putty and a lens. For the very best results, ensure your shoebox projector has at least two coats, and that you set the brightness on your smartphone to the full setting. Also, project onto a white screen in a completely darkened room.

As you can see above, the results are satisfactory (although photographing the results are tricky) but note that the results are a mirror image of what you might expect to see.

Have you tried this DIY project? Perhaps you have purchased a cardboard Smartphone Projector? Let us know what you think, and if you have any questions about this build, in the comments below.

Image Credit: Durova

  1. Chong Iskanda
    April 25, 2016 at 4:02 am

    Hmm how long does it take to make one unit?

  2. Suvam
    March 22, 2016 at 8:04 am

    I used a magnifying glass . But it didn't work. I am trying for 2 days but it is not working.Please please help me to resolve out this problem.

  3. Sofia
    February 21, 2016 at 8:35 am

    What is the purpose of painting the inside of the shoebox black?

    • Christian Cawley
      February 21, 2016 at 8:59 am

      TO reduce the spread of light inside the box. A black matt paint is perfect.

  4. Aditya Rai
    January 8, 2016 at 4:33 pm

    Please tell me more about the lens you use here? Which quality or diameter of lens is best or how many lens/es is/are required to get brighter image? Please tell me everything via this email ID - adityarai2727@gmail.com
    Thanks

  5. Affan
    January 6, 2016 at 7:40 pm

    Can we use a magnifying lens instead of biconvex lense.

    • harshal
      March 16, 2016 at 6:02 pm

      the bigger the better

  6. Muhammad Fahad
    November 26, 2015 at 7:58 am

    its work very well i got two different size projector lens which are perfectly working with my smart phone Huawei G750. if you use smart phone disable the auto rotate option and auto brightness and also put it on full brightness and adjust your smart phone colour temperature. two more things which were missing in that you can also insert the audio cable and charging cable for your device for long time running and good quality sound. do try this as well...

  7. Gten Zinzuwadia
    November 9, 2015 at 8:17 am

    I made the same with 90mm lens and using samsung smartphone,but unfortunately it is not working.i cannot see any clear image flashin on wall..can i know what should be the lens "mm" ??

  8. Anand Raj
    September 25, 2015 at 8:09 pm

    i have tried this and working fine......:)))
    but i have some questions that is, is there is any chance to increase the brightness and invert the image?

    • Shafiku
      December 30, 2015 at 2:34 am

      You may need smaller than that....you should try 60mm or 50 mm

    • Aditya Rai
      January 8, 2016 at 4:31 pm

      Yes this is possible to invert the image - just lock your phone's auto rotation and invert it to 180° simply. And this is not possible to increase the brightness of your phone more than 100% because every phone is come with its own lamp watt and you can't increase it more than 100%.

  9. Tangodelta
    May 21, 2015 at 8:47 pm

    I think this is a great article and can't wait to make one.
    Thanks Christian!

    Also, if you don't have something nice to say then keep it to yourself.

  10. Nazeem
    April 5, 2015 at 12:24 pm

    Perhaps he wanted as many as clicks on is add! the heading is not suited!

    • Christian Cawley
      April 8, 2015 at 3:43 pm

      You do me and MUO a disservice. The title is absolutely accurate. It's in the DIY section, so it's here for you to try and learn from. If you don't want to try it out for yourself, then that's fine.

  11. Dmitry
    April 5, 2015 at 11:57 am

    Smartphone screen is not _very_ bright - so image will be dimmer by inverse square law even if we assuming that ALL light from the smartphone gets to the screen.
    So basically it's very cool project to do together with kids (though version with magnifying glass will be a bit more educational) but for practical use i'm very sceptical...unless one had suitable lenses laying around and suddenly need larger screen no matter how bad it is.

    • Christian Cawley
      April 8, 2015 at 3:42 pm

      Youre absolutely right, Dmitry, but I don't believe that it is up to us to suggest how you might use the project.

  12. Brian G
    April 1, 2015 at 9:21 pm

    Is it okay if I use black duct tape instead of black paint? Also, I have an old pair of eye glass lenses, I think I can attach each of them to either end of a tin can and put a see through mirror in the middle of the inside of the can to replicate the cine lens. This way I don't have to buy a lense or wreck a camera.
    Maybe next April 1 I will get everything together and make it for April Fools day 2016. Back to you in 2016.

    • Christian Cawley
      April 3, 2015 at 8:00 am

      This isn't an April Fool. As evidenced by the link to Luckie's Smartphone Projector on Amazon.

  13. Muhammad Uzair
    April 1, 2015 at 2:34 pm

    April fool article :-P

  14. CTownBOS
    April 1, 2015 at 10:27 am

    Spell check failed me. Article.

  15. CTownBOS
    April 1, 2015 at 10:26 am

    Title of artickle is more than misleading, it's wrong. It doesn't mention the most important part, the lens

  16. Christopher
    April 1, 2015 at 7:13 am

    The lens is the key and the author has brushed right past the most important part. The article should have gone into more depth for step #2; maybe by explaining how to build a projection lens with a couple of bi-convex lenses from eBay or an old pair of binoculars, etc.

    • Justin
      April 1, 2015 at 9:24 am

      Thank you. It really bothered me. At the very least give sources. :/

    • Christian Cawley
      April 3, 2015 at 8:01 am

      "The article should have gone into more depth for step #2; maybe by explaining how to build a projection lens with a couple of bi-convex lenses from eBay or an old pair of binoculars, etc."

      No. I conceived this post and decided what should be included and what not for anyone wanting to build a low-cost smartphone projector. Building a lens is clearly beyond the scope of this, and would have been a distraction.

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