Archive for category Photography & Images
Monthly Science: Lithium Cells vs. Low Discharge Current
Posted by Ed in Electronics Workbench, Photography & Images, Science on 2019-02-01
The amount of energy you can extract from a battery depends strongly on the discharge current, which is why the advertised capacity always exceeds the real-world capacity. Testing the NP-BX1 batteries for my Sony HDR-AS30V at about an amp produces a reasonable estimate of their run time in the camera:
Even though defunct cells lack enough capacity to keep the camera alive during a typical bike ride, they should power a microcontroller or astable multivibrator for quite a while.
My CBA II has a 100 mA minimum test current, which is far higher than the 15-ish mA drawn by the Arduino Pro Mini / Nano and SK6812 LEDs in a vacuum tube light, so these tests should provide a lower bound on the expected run time:
The two dotted lines show a “good” battery (Wasabi 2017 K) tested at 100 mA has a 1 A·h capacity similar to the “defunct” batteries. Testing at 1 A drops the capacity by a factor of two and eliminates the relatively constant voltage part of its discharge curve.
Handwaving: a 15 mA load on a battery with 1 A·hr capacity should run for 66 hours, ignoring nuances like the Arduino’s minimum voltage requirement and LED minimum forward voltages.
A few days of informal (“Oh, it stopped a while ago”) testing showed 50 hour run times, with little difference in the results for batteries with 800 mA·h and 1300 mA·h capacity:
The red power LED remains on long after the SK6812 LEDs dim out and the Arduino stops running. The blue and green LEDs fade before the red LED.
The run time test data:
The 100 mA graph plotted against watt·hours has a similar shape:
You’d use those results for a constant power load similar to a camera or, basically, any electronics with a boost supply.
Ice Jewelry
Posted by Ed in Oddities, Photography & Images on 2019-01-26
We spotted this assortment of jewelry gleaming along Clove Creek:
A closer look at a necklace:
And the brooch:
The water level has been dropping for several days as the air temperature went from tolerably cold to well below freezing.
It’s better in person; I couldn’t get close enough to avoid using the Pixel’s digital zoom, so the images have more gritty texture than you’d expect.
Sony HDR-AS30V Helmet Camera: MicroSD Card Spacer
Posted by Ed in Machine Shop, Photography & Images on 2019-01-23
Sony tried, they really tried, to make their proprietary Memory Stick flash memory cards catch on, but the slot in their HDR-AS30V Action / Helmet camera accepts both Memory Stick Micro and MicroSD cards. The two cards have slightly different sizes, the AS30V’s dual-purpose slot allows MicroSD cards to sit misaligned with the contacts, and the camera frequently kvetches about having no card.
The only solution seemed to be starting the camera while watching the display to ensure the card worked, but it would sometimes joggle out of position during a ride.
I cut out a tiny polypropylene rectangle(-ish) spacer to fill the Memory Stick side of the slot, sized to fit between the spring fingers holding the MicroSD card against its contacts:
Not the best cutting job I’ve ever done, but it was an iterative process and that’s where I stopped. If this works and I have need for another / better spacer, I promise to do better.
The spacer’s somewhat mottled appearance comes from tapeless sticky (an adhesive layer on a peel-off backing: inverse tape!) applied to the top side, which will affix it to the slot. I’d rather glue the spacer to the MicroSD card, but then the card wouldn’t fit in the USB 3.0 adapter I use to transfer the files.
The chips along the left edge of silkscreen come from my fingernail, because pressing exactly there seems to be the best way to force the damn thing into the proper alignment.
So the slot + spacer looks like this:
The MicroSD card fits in the far side of the slot, facing toward you with contacts downward, thusly:
And then It Just Works™, at least on the very few rides we’ve gotten in during December and early January.
Incidentally, the blue and exceedingly thin latch finger holding the battery in place will snap, should you drop the camera on its non-lens end from any height. Conversely, should you drop it on the lens end, you can kiss the optics goodbye. Your choice.
Monthly Image: Red Oaks Mill Dam Flow
Posted by Ed in Photography & Images, Science on 2019-01-15
Some of our regular walks take us over the Rt 376 bridge downstream of the Red Oaks Mill dam and I try to take a picture whenever we cross.
For reference, two years ago in December 2016:
Red Oaks Mill Dam 2016-12-11
January 2018:
Red Oaks Mill Dam – 2018-01-13
April 2018:
Red Oaks Mill Dam – 2018-04-08
October 2018:
Red Oaks Mill Dam – 2018-10-29
November 2018:
Red Oaks Mill Dam – 2018-11-18
December 2018:
Red Oaks Mill Dam – 2018-12-31
The dam breast seem from the north (left in above pictures) in December 2018:
Red Oaks Mill Dam – north view – 2018-12-30
Searching for the obvious keywords will produce far more pictures than the subject may deserve.
Getting hydropower from the rubble would require considerable capital investment …
Imagemagick 6 vs. PDF
Posted by Ed in PC Tweakage, Photography & Images, Software on 2018-12-03
Come to find out Xubuntu 18.04 ratcheted the ImageMagick security settings up to a dangerous chattering whine:
convert p???.jpg "Machining D-bit Drills.pdf" convert-im6.q16: not authorized `Machining D-bit Drills.pdf' @ error/constitute.c/WriteImage/1037.
Fortunately, someone who understands this stuff encountered the problem before I did and posted a great description of the solution.
To forestall link rot, the process looks like:
cd /etc/ImageMagick-6/ sudo cp policy.xml policy.xml.base sudo nano policy.xml … change one line … policy domain="coder" rights="read|write" pattern="PDF"
It is completely unclear to me whether ImageMagick (as of ImageMagick 6.9.7-4 Q16 x86_64 20170114 ) requires or merely tolerates the vertical bar in place of commas, nor whether it’s in my best interest to replace "coder" with "*".
In any event, I can once again stuff bitmap images into PDF files.
Kindle Fire Picture Frame: Copying the Pictures
Posted by Ed in Photography & Images, Software on 2018-11-26
Being a bear of unbearable consistency, I save edited picture files with a description following the original camera-assigned sequence number:
IMG_20181108_190041 - Kindle Fire Picture Frame - Another Test Image.jpg
Yup, spaces and all.
Kindle Fire Picture Frame – Another Test Image
I store my general-interest pix chronologically by year, in subdirectories for interesting categories, so copying all the edited (a.k.a. “interesting”) pictures to the Kindle Fire becomes a one-liner:
cd /mnt/bulkdata/Cameras find 20?? -iname \*\ \*jpg -print0 | xargs -0 cp --parents -t /mnt/part/Pictures
The --parents parameter tells cp to recreate the directory structure holding the picture in the target directory, thereby keeping the pix neatly sorted in their places, rather than creating one heap o’ pictures.
Come to find out I’ve edited slightly over 7 k general-interest pictures in the eighteen years I’ve been using digital cameras, of maybe 27 k total pictures. Call it a 25% hit ratio; obviously I’m not nearly fussy enough.
Then there’s another 16 k project-related pictures, of which 10 k were edited into something useful. With an emphasis on utility, rather than aesthetics, a 60% hit ratio seems OK.
Which works out to half a dozen pictures a day, every day, for eighteen years. I loves me some good digital camera action!
Small Stone Moving By Itself
Posted by Ed in Photography & Images on 2018-11-17
A decorative snail emerged from within a large garden lettuce:
Snail – looking left
It seemed interested in its new surroundings:
Snail – looking right
And eventually set off on an adventure:
Snail – escaping
We returned it to the Great Outdoors, far from the garden goodies, and wished it well.
Sometimes, having eyes mounted on stalks would be advantageous, but I’m unwilling to give up opposable thumbs to get ’em.
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