Just a friendly reminder that most common types of thermal paper contain BPA or BPS. You really should be avoiding these endocrine disruptors when possible.<p><a href="https://www.pca.state.mn.us/green-chemistry/bpa-thermal-paper" rel="nofollow">https://www.pca.state.mn.us/green-chemistry/bpa-thermal-pape...</a>
Very cool. I made a Pi thermal printer photobooth almost exactly two years ago that worked on the same principle, although I wasn't crazy enough to try and cram it into a Polaroid shell. What seemed like a simple exercise turned into more research than what I thought I had tolerance for on a side project. IIRC from my experience there were two big problems: 1. versions matter when it comes to printer drivers, OS, and your hardware combo, and 2. the data buffer on thermal printers is not big enough for what you want to do (which is why it spits out random chars and symbols instead of your photo). The printer I was using had a buffer pin but ultimately I was short on time and patience so I opted instead to use imagemagick to convert and compress the photo before sending it to the printer. I used the booth for my nephew's birthday party and it survived real world use pretty well. You got a nice physical souvenir (I also added a "Happy Birthday" + date overlay to each image) and I set up a local server on the Pi that let people browse the digital versions of all the photos with a framework called Sigal. Very fun hardware project and I intended to publish a writeup outlining all the sharp corners I navigated but never got around to it.
> Long before the final assembly I'd wired the little LED under the viewfinder to one of the pi's GPIO. I'm not sure what it originally represented...<p>From the manual[1, 2]:<p><i>When you are not using flash, a red light may appear under the viewfinder as you begin to press the shutter button. It warns that the lighting on the scene is not bright enough for picture taking without a tripod or other firm support.</i><p>Also, this bit from the manual is somewhat amusing given the extraordinary chain of events occurring inside the hacked camera:<p><i>As you begin to press the shutter button, your camera releases sound waves to the central part of the scene. The frequencies are far beyond our range of hearing and travel at the speed of sound. The split second it takes for the sound to reach your subject and the echo to return is fed into a tiny electronic computer inside the camera. The computer uses this time measurement to calculate the distance between the camera lens and your subject, then signals a motor to turn the lens until your subject is in sharp focus. This extraordinary chain of events takes place in less than 1/3 of a second.</i><p>[1] <a href="http://www.cameramanuals.org/polaroid_pdf/polaroid_sonar.pdf" rel="nofollow">http://www.cameramanuals.org/polaroid_pdf/polaroid_sonar.pdf</a><p>[2] Found via <a href="http://butkus.org/chinon/" rel="nofollow">http://butkus.org/chinon/</a> which itself is a lovely 1990's style web-site. I couldn't help but donate $3.
Makes for a much more in-depth and capable version of the Game Boy Camera + Printer: <a href="https://en.wikipedia.org/wiki/Game_Boy_Camera" rel="nofollow">https://en.wikipedia.org/wiki/Game_Boy_Camera</a> an object of gadget lust for me when I was growing up
I built pretty much exactly the same thing, but without the polaroid camera shell, but did not get around to writing about it. A couple suggestions:<p>1) Apply exposure compensation and dithering to the image. this allows a better fidelity output. Example: [<a href="https://i.imgur.com/eCLRs8Q.jpg" rel="nofollow">https://i.imgur.com/eCLRs8Q.jpg</a>] you'll have to play around with the exposure depending on the camera you're using.<p>2) the 3" paper printer would make for a much better output than the 2" one, simple because the former is closer to an actual photo size.
This chapter was funny.<p>"Cut the USB<p>With time running out and no better option in mind, I broke out the cutting disks and surgically removed one of the USB hub circuits from the 7-port hub."<p>Regarding his earlier rant about USB hub quality, I have to agree. It's getting harder to come by a robust USB hub nowadays. Bad connector and power supply quality (USB hub PSUs are electrically noisy and way under powered for the number of ports).
Why I love Hacker News. I read an article about a cool hobbyist project, and my mind leaps to someone at work was having trouble with a thermal printer... and I just realised what the fix for their problem is...a total tangent but that often happens.<p>I love the idea btw. My wife wants one already.
I kinda like the concept, too. Beyond just the whole execution, which is really well done. Thermal paper disappears over time. So this in turn means these photos are somewhat ephemeral. I haven't lived long enough to know whether I prefer photos or pure memory, but I have to assume there's something redeeming about relying solely on your memory.<p>But I also love that my children one day will be able to see perfectly accurate photos of myself in my 20s, whereas photos of my parents + their parents have considerable wear.<p>Anyway, love this post. Thanks for sharing!
Just an FYI regarding thermal paper and highlighter pens.<p>At a former job some of the staff were printing some free product vouchers. On each they highlighted certain data to make it easy to spot. Well they soon found out that a highlighter on thermal paper will erase what is highlighted. It takes some time but it does a great job of erasing it. I don't know how or what the chemical process is but it does work, or fail, whatever your goal was I guess.
This is an awesome project!<p>Also, for those unaware, people at Polaroid thought so, too, and released a thermal-printing color Polaroid SNAP a few years ago. It makes prints comparable to Fuji Instax, but the camera is digital and pocketable.<p>I've owned it for a couple of years, and I call it the friend-maker camera.
He says in the video you can’t buy one but I recently bought a Polaroid camera as a gift at Urban Outfitters for $100, plus the expensive film ($30 for 8 shots) that goes with it. Is this different in some way?