Building A Custom Camera Mic

May 21, 2020 by Lewin Day 2 Comments

Most consumer-grade cameras these days come with adequate microphones built in. However, as with all hardware made down to a price point, there’s room for improvement. [M. Ploegmakers] decided to whip up a better microphone setup for his Sony A6300, with the Dumbbell Mic as the result.

The microphone is based around an electret condensor element, which provides good performance at a remarkably low price. This is then integrated with a preamp circuit to bring the audio up to the appropriate level for the camera to record along with the video. Switches on board set the gain level, as well as changing the mic to operate with or without phantom power, where available. The electronics is wrapped up in a 3D-printed enclosure, designed to mount on top of the camera for use out in the field.

It took some experimentation, but now [M. Ploegmakers] has a custom mic rig that records straight into the camera, avoiding the need to splice audio and video back together in post. If your camera lacks an audio input, you might have to do a little more work to hack one in, though!

Poking Around Inside Of A Linux Security Camera

May 20, 2020 by Tom Nardi 21 Comments

This deep dive into the Linux-powered Reolink B800 IP camera started because of a broken promise from its manufacturer. When [George Hilliard] purchased a kit that included six of the cameras and a video recorder, the website said they were capable of outputting standard RTSP video. But once he took delivery of the goods, and naturally after his return window had closed, the site was updated to say that the cameras can only function with the included recorder.

Taking that as something of challenge, [George] got to work. His first big break came when he desoldered the camera’s SPI flash chip and replaced it with a socket. That allowed him to easily take the chip out of the device for reading and flashing as he tinkered with modifying the firmware. After adding cross-compiled versions of busybox, gdb, and strace to the extracted firmware, he bundled it back up and flashed it back to the hardware.

If you think that’s the end of the story, it isn’t. In fact, it’s just the beginning. While getting root-level access to the camera’s OS would have potentially allowed for [George] to dump all the proprietary software it was running and replace it with open alternatives, he decided to take a different approach.

Instead of replacing the camera’s original software, he used his newly granted root powers to analyze it and figure out how it worked. This allowed for to sniff out some very suspect “encryption” routines built into the software, and eventually write his own server side in Rust that finally allowed him to use the cameras with his own server…albeit with a bit more work than he bargained for.

Projects like these are a fantastic look at real world reverse engineering, and a reminder that sometimes achieving your ultimate goal means taking the long way around. Even if you’re not in the market for a hacked security camera, there’s no doubt that reading the thorough write-up [George] has prepared will teach you a few things. But of course, we’d expect no less from a guy who runs Linux on his business card.

ESP32 Trail Camera Goes The Distance On AA Batteries

May 18, 2020 by Tom Nardi 34 Comments

There’s no shortage of things to like about the ESP8266 and ESP32, but if we had to make a list of the best features these WiFi-enabled microcontrollers have to offer, their power management capabilities would certainly be near the top. Which is how we assumed [Mark] was able to take a whopping 23,475 pictures on his ESP32 camera while powered by nothing more exotic than four AA batteries from the grocery store.

But as it turns out, the full story is quite a bit more interesting. As far as we can tell, [Mark] isn’t bothering with the ESP32’s sleep modes all. In fact, it looks like you could pull this trick off with whatever chip you wanted, which certainly makes it worth mentally filing away for the future; even if it depends on a fairly specific use case.

In the most simplistic of terms, [Mark] is cutting power to the ESP32 completely when it’s not actively taking pictures. The clever circuit he’s come up with only turns on the microcontroller when a PIR sensor detects something moving around in front of the camera. Once the chip is powered up and running code, it brings one of its GPIO pins high which in turn triggers a 4N37 optoisolator connected to the gate on the circuit’s MOSFET. As long as the pin remains high, the circuit won’t cut power to the ESP32. This gives the chip time to take the requested number of pictures and get everything in order before bringing the pin low and allowing the circuit to pull the plug.

If you’re looking to maximize runtime without wrangling any MOSFETs, we’ve seen some excellent examples of how the low power modes on the ESP8266 and ESP32 can be put to impressive use.

[Thanks to Jason for the tip.]

A Hot Printer For Cool Selfies

May 7, 2020 by Moritz v. Sivers 12 Comments

Randomly buying some hackable gadgets just because they are cheap and seem potentially interesting for future projects is something that most of us can relate to. It also happened to [fruchti] when he bought five thermal printer modules without any specific purpose for them in mind. It was not until several years later that he put them to good use for his inverse thermal camera project.

The name perfectly summarizes the device’s function which is to convert images to heat instead of the other way around. To put it in a less cryptic manner, [fruchti] built a selfie camera that instantly prints out pictures on thermochromic paper. The project would have been easy to implement on a Raspberry Pi but instead, he chose a more minimalist approach by using an STM32 microcontroller. This involved some challenges because the MCU didn’t have enough RAM to store an entire frame and the camera module came without a FIFO buffer. To capture and store the image data [fruchti] applied a line-by-line dithering algorithm which is described in detail in his accompanying blog post while the corresponding code is available on GitHub. Even though the case was improvised from scrap PCB materials the finished device still looks great. In particular, the fuse holders that are being used to hold the paper roll make it almost steampunk.

Naturally, this is not the first time we have seen thermal printers being used for instant picture taking and it probably won’t be the last.

Start Printing From Film For Around £100

May 3, 2020 by Jenny List 39 Comments

For the vast majority of readers, the act of taking a photograph will mean reaching for a mobile phone, or for a subset of you picking up a digital camera. A very small number of you will still use chemical film for its versatility and resolution, and we’re guessing that more would join those ranks if some of the cost barriers to doing so could be reduced.

It would be near-impossible to reduce the cost of a chemical photograph to the infinitely repeatable click of a digital camera shutter, but at least if the cost of a darkroom is intimidating then [Sroyon Mukherjee] has an interesting post over at 35mmc about how a darkroom for black-and-white printing from negatives can be equipped for less than £100 ($123). It’s a fascinating read even if your photography remains firmly in the digital, because along the way it explains some of the mysteries of the process. Few people had this type of equipment at home even in the days when most of us took our films to the drugstore, so as time passes this knowledge is concentrated among an ever narrower group.

The guide is full of useful hacks. Finding a second-hand enlarger takes an element of patience, but once it has been secured there are a variety of other essential items. The red safe light can be as simple as a mobile phone flashlight with a red filter, but we learn the trick of exposing a sheet of photographic paper with a coin laid on it to check that no white light is sneaking in. One of the main points of the piece is that there is no need for a special room to make a darkroom, and we take a tour of a few photographers’ set-ups in hallways, bathrooms, and basements.

So if you spot an unloved enlarger just waiting for a hacker to pass by, this might inspire you to do something with it. He doesn’t cover the development process, but if you throw caution to the winds you could always try coffee and vitamin C.

[via Hacker News]

New Part Day: Raspberry Pi Camera Gets Serious With 12 Megapixels & Proper Lenses

May 1, 2020 by Jenny List 39 Comments

The Raspberry Pi Foundation have slipped out a new product, a $50 camera module with a larger sensor that increases the resolution from the 8 megapixels of its predecessor to a Sony IMX477R stacked, back-illuminated 12.3 megapixel sensor, and most interestingly adds a mounting ring for a C mount lens (the kind used with CCTV equipment) in place of the tiny fixed focus lenses of past Pi cameras. In addition there is a standard threaded tripod mount on the module, and an adapter ring for CS mount lens types. The camera cannot be used without a lens, but there are a few options available when ordering, like 16mm telephoto or 6mm wide angle lenses, if you do not already have a suitable lens on hand.

It’s an exciting move for photography experimenters, because for the first time it offers an affordable way into building custom cameras with both a higher quality sensor and a comprehensive selection of interchangeable lenses. We can imagine that the astronomers and microscopists among us will be enthusiastic about this development, as will those building automated wildlife cameras. For us though the excitement comes in the prospect of building decent quality cameras with custom form factors that break away from the conventional, because aside from a period when consumer digital cameras were in their infancy they have stuck rigidly to the same form factor dictated by a 35mm film canister. It’s clear that this module will be made into many different projects, and we are looking forward to featuring them.

At the time of writing the camera is sold out from all the usual suppliers, which follows the trend for Raspberry Pi products on their launch day. We didn’t manage to snag one, but perhaps with such an expensive module it’s best to step back for a moment and consider the project it will become part of rather than risking it joining the unfinished pile. While waiting for stock then perhaps the next best thing is to 3D print a C mount adapter for your existing Pi camera, or maybe even hook it up to a full-sized SLR lens.

Pi Cam Replaces Pinhole And Film For Digital Solargraphy

April 28, 2020 by Dan Maloney 29 Comments

Solargraph from a one-year exposure on film. Elekes Andor / CC BY-SA

Have you ever heard of solargraphy? The name tells you much of what you need to know, but the images created with a homemade pinhole camera and a piece of photographic film can be visually arresting, showing as they do the cumulative tracks of the sun’s daily journey across the sky over many months. But what if you don’t want to use film? Is solargraphy out of reach to the digital photographers of the world?

Not at all, thanks to this digital solargraphy setup. [volzo] searched for a way to make a digital camera perform like a film-based solargraphic camera, first thinking to take a series of images during the day and average them together. He found that this just averaged out the sun from the final image. His solution was to take a pair of photos at each timepoint — one correctly exposed to capture the scene, and one stopped way down to just capture the position of the sun as a pinprick of light. All the foreground images are averaged, while the stopped-down sun images are overlaid upon each other, producing the track of the sun across the sky. Add the two resulting images and you’ve got a solargraph.

To automate the process, [volzo] used a Raspberry Pi and a Pi-Cam fitted in a weatherproof 3D-printed box. A custom hat powers up the Pi every few minutes, which boots up and takes the two pictures. Sadly, the batteries only last for a couple of days, so those long six-month exposures aren’t possible yet. But [volzo] has made all the sources available, so feel free to build on his work. If you prefer to use a DSLR for the job, this Bluetooth intervalometer might help.