Pocket Fresnel Lens

Wallet Magnifier Twin Pack.jpeg I'm a maintenance electrician and sometimes need to read tiny serial numbers in dark dirty places, or the color code of a resistor or some other value or rating that is difficult to accurately read with the naked eye, and for the past six months I have found that this wallet lens to be the perfect solution. Outside of magnifying small text, I have even used this to start a fire. The pocket Fresnel makes a brilliant addition to my kit of tools at my job but also is a useful survival tool when I'm outdoors. It fits in my wallet which I'm never without. Even when my kids play with my keys and I can't find them afterwards (or use the tools on my keyring) I know I've still got one tool tucked away. Best part of this lightweight super practical EDC? It's super cheap! I got mine in a 6-pack from Lee Valley, but you can get similar ones elsewhere online. --John Love Wallet Fresnel Lens $2 Don't forget to comment over at Cool Tools. And remember to submit a tool!


  1. I’ve discovered that simply zooming in with the iPhone’s camera yields amazing results with fine print, bringing nearly microscopic text into clear relief.

    Plus, if you can’t decipher it right then… *snap*!

    1. “I’ve discovered that simply zooming in with the iPhone’s camera yields amazing results with fine print, bringing nearly microscopic text into clear relief.”

      Everyone else is ignoring that, so I’ll just assume you’re being sarcastic too, right?

      1. Actually what he describe does work. Used it a couple of time with my 3gs, but you need good light.

        1. I’m sure it works. But we’re talking about the difference between a several hundred dollar smart phone and a 2 dollar plastic lens that anyone can carry around in their pocket.

          1. I don’t see that he advocated buying an iPhone.

            I actually have my iPhone more often on me than my wallet. I don’t really need my wallet during work days, not even money, so at least during the summer when I don’t need a jacket I leave it home.

            I would also leave my wallet in my hotel room during walks, but not the phone, because that comes with a map and a camera.

            I do carry some assorted stuff around, but in nearly all cases where such a lens would work better than the phone, I also have a cheap, but perfectly usable loupe in my laptop bag.

            But old-age far-sightesness hasn’t really kicked in yet, though the early signs are there – I’ll probably find such a lens useful in about ten years to so. Until then, it’d be just a gadget or affection for me, like others think about the knife I carry all of the time or the small flashlight I try to bring along whenever I don’t forget it.

  2. I’ve found these to scratch too easily; I prefer to carry a loupe.

    Now, my 1-square-meter fresnel is a different story altogether…

    1. now that’s what I’m talking about. nothing like melting pennies with the power of the sun

  3. I used to have an 8.5×11 size one as a kid. I think it was used for reading papers and the like (just guessing by the size, I was like 8).

    But man could I burn some stuff up with that thing. Only problem I found was it didn’t work that well in the woods. You know all those trees blocking the sunlight.

  4. I think you can walk into Lee Valley Tools, grab one of their little clipboards and write random numbers, then go to the counter and hand it over.

    If any of the numbers result in a hit, chances are, it’ll be a Cool Tool.

  5. I put one of these in my wallet, and forgot all about it. Until one evening, my mother was in town for a visit and we were out at a restaurant. She had trouble reading the menu, and had left her reading glasses in the car. I pulled out the wallet lens and my flashlight, and she was able to read the menu easily.

    She liked my wallet lens so much, I gave it to her, and bought another to keep in my wallet. As for scratching, the one I have came with a thin protective sleeve, and I haven’t seen a scratch yet.

  6. Yeah, I have one in my wallet too. They are perfect for seeing the small stuff. Prescription/Medicine directions, Coupon expiration dates, all sorts of regular stuff. It’s also a great eye doctor visitation reminder. Every time I pull it out I say to myself, “Hmm, maybe it’s time to see eye doctor?”. It’s not a very good indicator because I never end up seeing the eye doctor.

    Good stuff.

  7. I <3 PaulR's comment. And he's absolutely right.

    Next time I'm in LV, I'll enter the code for the six pack and then five random number strings to test this theory. Look for my report in a week or so.

  8. I’m presbyopic but myopic, so to see close I just lift up my specs. To see really close I sometimes carry an old microscope eyepiece- turn it around and it makes a great loupe.

    1. @Anon #10

      Thanks for the tip. That’s a price even a cheapskate like me can bear. Plus gifts for my, ahem, more mature friends.

  9. For the longest time, American Science & Surplus (the Chicago institution) had a GIANT fresnel fer next to nothing. Missing that opportunity was probably the mistake of my lifetime. They’re still more or less available, but in the neighborhood of $100.

    …and they melt pennies:

    1. I was able to get my giant lens for about $60. They came from old rear-projection TV stock, a little over a square meter in area. Buying just one was too expensive with the shipping charges (they can roll up, but still need a pretty long box), but they’re so thin that buying a bunch at once didn’t increase that price. I put up a Craigslist ad for other people looking to build death rays, and was able to put in an order for five at once.

  10. I have a bookmark fresnel lens, and I love it!

    I especially enjoy holding it up to my eyes or mouth to get a reaction out of people.

  11. how do you pronounce the word “fresnel”? do you read the “s” or is it silent with an accent on the last “e”?

  12. I’ve carried one of these for years. Gave it to my father on day when he couldn’t read something, I forget what. Didn’t think I’d miss it until one day I couldn’t decipher a serial number on the back of a new piece of electronic equipment. Immediately went out and bought two more. The ones I buy come in a slipcase to protect them from scratches.

  13. I have something similar in my wallet, but it has a built in LED light making it far more handy. Got mine in Ottakers when buying a book… you know, those funny objects with many sheets of paper that have been printed on…

    not sure who makes mine or how much it cost. It was an impulse buy as it was in the till display along with fancy bookmarks etc.

  14. In case you saw the videos of giant fresnel lens and want one of your own…they are easily scavenged from an old rear-projection TV.

    Check your local craigslist and you might be surprised how many are being given away for free. All you have to do is pry off the front cover exposing the screws that hold the lens in, remove them and the giant fresnel lens is there for the taking! Mine also had a nice sheet of clear acrylic and a light diffuser.


    Dan at greenpowerscience.com has a ton of fun videos…

    Just remember to be careful and treat your large Fresnel lens with the same caution you’d use for a propane torch – don’t pass your body in front of the beam and don’t leave it unattended!

Comments are closed.