Archive for category Photography & Images
The Barbie-themed microscope light I built from an angel eye LED ring worked fine for the last six years (!), but a much brighter ring with 60 aimed 5 mm LEDs for $17 delivered from a US seller caught my eye:
Although this ring looks much more professional, it didn’t quite fit the microscope, being designed for a round snout rather than a squarish one. This snout has a 47-ish mm threaded ring intended for filters & suchlike, so I built an adapter between that and the 60 mm ID of the LED ring:
The ring came with three long knurled screws which I replaced with much tidier M3 socket-head screws going into those holes:
The part going into the snout threads is deliberately (honest!) a bit small, so I could wrap it with soft tape for a good friction fit. The Barbie Ring didn’t weigh anything and I wound up using squares of double-sticky foam tape; it could come to that for this ring, too.
The adapter features a taper on the bottom for no particularly good reason, as the field-of-view tapers inward, not outward:
Seen from the bug’s POV, it’s a rather impressive spectacle:
The control box sports a power switch and a brightness knob. Come to find out the ring is actually too bright at full throttle; a nice problem to have.
That was easy!
The OpenSCAD source code as a GitHub Gist:
I’m towing a trailer of groceries southbound on Rt 376 (a.k.a. Hooker Avenue in this section), intending to turn right onto Zack’s Way for a library stop.
T=0.00 s, car @ 26.4 mph, me @ 19.8 mph
The transverse cracks through the asphalt are a convenient 60 ft apart, with the last one 20 ft from the stop line, and the frame numbers tick along at 60 frame/sec, so you can easily compute distances, times, and speeds.
I’ll be turning right at the intersection. The light is green.
T= 2.07 s, car @ 26.7 mph, me @ 19.7 mph
Now I can see the car’s right turn signal, so this might not end well. I can’t jam on the brakes and avoid a collision by dumping the bike at speed; I’ll slide under the car in the middle of the turn.
T=4.15 s, 15.2 mph
I’m 20 feet from the stop line and, suddenly, the driver also realizes this might not end well.
What he doesn’t know is that my trajectory must use the traffic lane: the shoulder around the corner is deteriorated, with several potholes, and vanishes completely where the intersection paving ends.
The driver is turning wide, into the opposing traffic lane, but if I weren’t lining up for the turn, we’d be on a collision course. My line will take me just to the left of the seemingly tiny, but very deep, pothole just ahead.
Leaning hard into the turn, but our paths won’t cross.
I’m back upright in the middle of the lane, with the shoulder ending in a pothole to my right.
Remember, I’m wearing a fluorescent (“safety”) orange shirt, running a blinky light (which is also the rear camera), and towing a trailer with a fluttering flag: I am not inconspicuous!
In case there’s any question:
The rest of the ride proceeded without incident …
Early spring brings out large turkey flocks and provides a window into their otherwise rather private lives.
Despite all the strutting and posturing by the males, the ladies call the shots. When we see a hen go hull-down like this, we know what’s about to happen:
Getting into the right position seems remarkably awkward and requires some cooperation:
When her head and tail pop up, you know the thing is going right:
And a back massage always feels so fine:
Then he’s back to strutting & posturing:
We hope they’ll show us their chicks …
Taken with the DSC-H5, hand-held through two panes of 1955-era window glass: ya get what ya get.
The first pleasant day after a long string of snow and rain got us outside again:
The honeybee at Mary’s elbow escorted us for a bit, then flew between us and continued on her mission.
Despite appearances, she passed a few inches from my helmet:
We all agreed: it was a fine day for a ride and a flight!
Apparently she wanted to use the bird feeder atop the post festooned with plastic squirrel deterrence. Not being Elastigirl, she couldn’t quite stretch from rail to feeder, eventually gave up trying, and flapped to the driveway.
We’ve been turkey-watching for nearly two decades, it’s been eight years since we saw a turkey on the patio, and a few days after I set up the yard camera, shazam, this bird shows off for my friend in Raleigh while I’m in the Basement Laboratory. I’m insane with jealousy.
In point of fact, turkeys seem perfectly aware of people inside the house, so it’s not surprising they avoid the patio. When we move close to a window, the flock decides it has business elsewhere and, generally without haste or confusion, flows over the hill and away.
Obviously, I must set up motion detection and capture some images …
Thinking of a 60 kHz crystal filter front end for the WWVB receiver brought a little bag of 32.768 kHz crystals to the surface; I figured I could use them as crash test dummies while a bag of 60 kHz crystals travels around the planet. Come to find out they don’t behave quite like crystals and a bit of investigation shows the little cans contain tuning fork resonators, not crystal slabs.
I had to see that, so I grabbed the base of one in a pin vise:
I don’t know the part number for those resonators, but it’s something like AT26, where the “26” means a cylindrical can 2 mm OD and 6 mm long, more or less.
Notching the can at the chuck with a triangular file, then wiggling the can with needle-nose pliers, eventually broke it off:
The other side:
A look through the microscope show they’re transparent, with laser trim scars on the ends:
The “holes” are unplated quartz areas, clear as the finest glass.
Not what I was expecting to see, at all!
At first, the yard camera worked fine, but a few days later the stream of JPEG images would unpredictably stall. I connect to it through a public-key SSH session and, sometimes, the login would stall for tens of seconds and, with a session set up, various exciting operation like, say,
htop would unpredictably stall; if I waited long enough, they’d complete normally.
It’s a known-good card from a reputable supplier, not that that means much these days. The camera flash highlights the gritty silkscreen (?) texture of the orange overlay, but the production value seems high enough to pass muster.
Popping the card in my desktop PC showed:
- It remains functional, at least to the extent of being mount-able and write-able
3probe --time-ops /dev/sdbshowed it still held 16 GB
fsck -fv /dev/sdbshows no problems
- Both partitions looked good
So I shrank the main partition to 7.5 GB, copied the image to the desktop PC’s SSD, fired up the Token Windows Laptop, ran the Official SD Card Formatter, and discovered that it thought the card had only 63 MB (yes, MB) available. That’s the size of the FAT
boot partition, so I returned the card to the desktop PC, unleashed
gparted on it, blew away the partitions, reformatted the whole thing to one 16 GB FAT32 partition, and stuck it back in the laptop, whereupon the Official Formatter agreed it had every byte it should.
A format-with-overwrite then proceeded apace; the card doesn’t support format-with-erase.
Back in the desktop, I copied the saved image back onto the card which, en passant, blew away the just-created FAT format and restored the Raspbian partition structure. The 8 GB of that copy proceeded at an average 12.1 MB/s. I did not watch the transfer closely enough to notice any protracted delays.
Back in the Pi, the card booted and ran perfectly, sending an image every second to the laptop (now running its usual Mint Linux) on the guest network:
SSH sessions now work perfectly, too, and commands no longer jam.
So it seems a good-quality MicroSD card can experience protracted delays while writing data, to the extent of tens of seconds, stalling the Pi in mid-operation without producing data errors or any other symptoms.
It’s not clear the Official Formatter does anything that simply copying the image back to the card wouldn’t also accomplish, although overwriting the entire 16 GB extent of the card exercises all the cells and forces the card controller to re/de/un/allocate bad blocks. If, indeed, the blocks are bad, rather than just achingly slow.
Moral of the story: Don’t use MicroSD cards as mass storage devices, at least not for industrial applications that require consistent performance.