Canon Arc Form Drive exploded. Credit: Markus Kohlpaintner

A Deep Dive Into Canon Autofocus Lenses

March 11, 2025 by 7 Comments
Credit: Markus Kohlpaintner

Although taken for granted these days, autofocus (AF) used to be a premium feature on film- and digital cameras, with [Markus Kohlpaintner] taking us through an exhaustive overview of Canon’s AF systems and how they work. On Canon cameras AF became a standard feature with the introduction of its EF lenses in 1987, which are found on its EOS SLR (single-lens reflex) series of professional and prosumer cameras.

Over the decades, Canon has used many different AF drive mechanisms within these lenses, all with their own pros and cons. The article goes through each of them, starting with the original Arc-Form Drive (AFD) and ending with the newest Voice Coil Motor (VCM), showing their internal construction.  Of note are the USM (ultrasonic motor) types of AF systems that use a piezoelectric motor, the functioning of which using a traveling wave across the stator is also detailed, including the integrated feedback control system.

Ultimately the end user is mostly concerned with how well the AF works, of course. Here the biggest difference is probably whether manual adjustment is possible, with not all AF systems supporting full-time manual adjustment. With the newer AF systems this manual adjustment is now performed digitally rather than with a direct coupling. Although few people probably give AF much thought, it’s fascinating to see how much engineering went into these complex systems before even touching upon the algorithms that decide what to focus on in a scene.

Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Batwing Typewriter

March 11, 2025 by 7 Comments

[Alex] of YouTube channel [EastMakes] wrote into tell me about his fantastic QWERTY ‘hexpansion’ board for the 2024 EMF Tildagon badge, and [Alex], I’m super glad you did. The system works!

Let’s back up a bit. Essentially, the idea is to have a badge that can be used beyond a single camp, with the creation of expansion boards being the other main attraction. Our own [Jenny List] covered the badge in detail back in June 2024 when she got her hands on one.

A pair of hands holds the 2024 EMF Tildagon badge with a QWERTY keyboard Hexpansion built by [EastMakes].
Image by [EastMakes] via YouTube
[Alex] started by importing the Tildagon into Fusion360 and designing a way for the keyboard to attach to it physically. He then modeled the keyboard after the Blackberry types that can be found on Ali using the official EMF buttons established in earlier badges.

This QWERTY hexpansion is based on the RP2040, which is soldered around back and visible through the 3D-printed backplate. In order for the 90°-oriented board to align with the… not-90° connector, [Alex] built a little meander into the PCB.

The default OS on the Tildagon doesn’t know natively what to do with the serial messages from the keyboard, so [Alex] wrote an application that reads them in and decodes them. Be sure to check out the build and walk-through video after the break.

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Tiny Laptop Gets A New Case And An Unlocking

March 11, 2025 by 21 Comments

Unless you’ve got an especially small lap, calling the Toshiba Libretto a laptop is a bit of a stretch. The diminutive computers from the mid-1990s had a lot of the usual laptop features, but in an especially compact and portable case that made them a great choice for anyone with an on-the-go lifestyle.

Fast-forward thirty years or so, and the remaining Librettos haven’t fared too well. Many of them have cases that crumble at the slightest touch, which is what led [polymatt] to undertake this meticulous case replacement. The effort started with a complete teardown; luckily, the lower aluminum-alloy shell was in fine shape, but the upper case parts were found to be almost too deteriorated to handle. Still, with a little patience and the judicious application of tape, [polymatt] was able to scan the case pieces on a flatbed scanner and import them into his CAD package. Great tip on the blue-tack for leveling the parts for accurate scanning, by the way.

After multiple rounds of printing and tweaking, [polymatt] had a case good enough to reassemble the Libretto. Unfortunately, the previous owner left an unwanted gift: a BIOS password. Disconnecting the CMOS battery didn’t reset it, but a little research told him that shorting a few pins on the parallel port on the machine’s dock should do the trick. It was a bit involved, requiring the design and subsequent bodging of a PCB to fit into the docking port connector, but in the end he was able to wake up a machine to all its Windows 95 glory. Better get patching.

In a time when laptops were more like lap-crushers, the Libretto was an amazing little machine, and thirty years on, they’re well worth saving from the scrap heap. Hats off to [polymatt] for the effort to save this beauty, and if he needs tips on reading data from any PCMCIA cards that may have come with it, we’ve got him covered.

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TrapC: A C Extension For The Memory Safety Boogeyman

March 11, 2025 by 53 Comments

In the world of programming languages it often feels like being stuck in a Groundhog Day-esque loop through purgatory, as effectively the same problems are being solved over and over, with previous solutions forgotten and there’s always that one jubilant inventor stumbling out of a darkened basement with the One True Solution™ to everything that plagues this world beset by the Unspeakable Horror that is the C programming language.

As the latest entry to pledge its fealty at the altar of the Church of the Holy Memory Safety, TrapC promises to fix C, while also lambasting Rust for allowing that terrible unsafe keyword. Of course, since this is yet another loop through purgatory, the entire idea that the problem is C and some perceived issue with this nebulous ‘memory safety’ is still a red herring, as pointed out previously.

In other words, it’s time for a fun trip back to the 1970s when many of the same arguments were being rehashed already, before the early 1980s saw the Steelman language requirements condensed by renowned experts into the Ada programming language. As it turns out, memory safety is a miniscule part of a well-written program.

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Josephine Cochrane Invented The Modern Dishwasher — In 1886

March 11, 2025 by 42 Comments

Popular Science has an excellent article on how Josephine Cochrane transformed how dishes are cleaned by inventing an automated dish washing machine and obtaining a patent in 1886. Dishwashers had been attempted before, but hers was the first with the revolutionary idea of using water pressure to clean dishes placed in wire racks, rather than relying on some sort of physical scrubber. The very first KitchenAid household dishwashers were based on her machines, making modern dishwashers direct descendants of her original design.

Josephine Cochrane (née Garis)

It wasn’t an overnight success. Josephine faced many hurdles. Saying it was difficult for a woman to start a venture or do business during this period of history doesn’t do justice to just how many barriers existed, even discounting the fact that her late husband was something we would today recognize as a violent alcoholic. One who left her little money and many debts upon his death, to boot.

She was nevertheless able to focus on developing her machine, and eventually hired mechanic George Butters to help create a prototype. The two of them working in near secrecy because a man being seen regularly visiting her home was simply asking for trouble. Then there were all the challenges of launching a product in a business world that had little place for a woman. One can sense the weight of it all in a quote from Josephine (shared in a write-up by the USPTO) in which she says “If I knew all I know today when I began to put the dishwasher on the market, I never would have had the courage to start.”

But Josephine persevered and her invention made a stir at the 1893 World’s Fair in Chicago, winning an award and mesmerizing onlookers. Not only was it invented by a woman, but her dishwashers were used by restaurants on-site to clean tens of thousands of dishes, day in and day out. Her marvelous machine was not yet a household device, but restaurants, hotels, colleges, and hospitals all saw the benefits and lined up to place orders.

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Homebrew Traffic Monitor Keeps Eyes On The Streets

March 11, 2025 by 63 Comments

How many cars go down your street each day? How fast were they going? What about folks out on a walk or people riding bikes? It’s not an easy question to answer, as most of us have better things to do than watch the street all day and keep a tally. But at the same time, this is critically important data from an urban planning perspective.

Of course, you could just leave it to City Hall to figure out this sort of thing. But what if you want to get a speed bump or a traffic light added to your neighborhood? Being able to collect your own localized traffic data could certainly come in handy, which is where TrafficMonitor.ai from [glossyio] comes in.

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Red and gold bakelite Philco farm radio on a workbench

Hacking A Heavyweight Philco Radio

March 10, 2025 by 6 Comments

There’s something magical about the clunk of a heavy 1950s portable radio – the solid thunk of Bakelite, the warm hum of tubes glowing to life. This is exactly why [Ken’s Lab] took on the restoration of a Philco 52-664, a portable AC/DC radio originally sold for $45 in 1953 (a small fortune back then!). Despite its beat-up exterior and faulty guts, [Ken] methodically restored it to working condition. His video details every crackling capacitor and crusty resistor he replaced, and it’s pure catnip for any hacker with a soft spot for analog tech. Does the name Philco ring a bell? Lately, we did cover the restoration of a 1958 Philco Predicta television.

What sets this radio hack apart? To begin with, [Ken] kept the restoration authentic, repurposing original capacitor cans and using era-appropriate materials – right down to boiling out old electrolytics in his wife’s discarded cooking pot. But, he went further. Lacking the space for modern components, [Ken] fabbed up a custom mounting solution from stiff styrofoam, fibreboard, and all-purpose glue. He even re-routed the B-wiring with creative terminal hacks. It’s a masterclass in patience, precision, and resourcefulness.

If this tickles your inner tinkerer, don’t miss out on the full video. It’s like stepping into a time machine.

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