gifs for Z-stacks?

I am gearing up for tests of a new iteration of my Lieberkühn reflector for 58mm diameter, f=35mm lens for macrophotography. This will be my first print in Shapeways bronzed steel material. In the meantime, enjoy some Lieberkühn enhanced macrophotography, in gif format.

The subject is the lovely Osmia aglaia, a beautiful blue solitary bee from North America. Compression for the GIF format does some fuzzy things to the photos, but it was still worth the experiment for a simple way to display z-stacks. Click for larger versions.





I’ve also recently launched a new double threaded lens cap: stays on the lens when bumped or carried, and now each lens cap fits two standard lens diameters instead of one. They are available here in a variety of sizes, and you can see the firm attachment compared to squeeze lens caps demoed here . I have only tested this design out in the lens diameters I and a few friends own and use. I now need more photographers to try it out and provide feedback. With this in mind I will keep the Shapeways price as low as possible until some more theBilder threaded lens caps have had a run in the wild!

We mustn’t liken a black hole to a baked good

We also mustn’t use the royal we

A prevalent mindset in science journalism is that in order to make a subject accessible, it first must be dumbed-down. I suggest we all make efforts to recognise the difference between a simplification and a replacement with simple ideas. A simplification is a description that isn’t comprehensive, but is still true. Replacing a complex idea with simple one, on the other hand, often boils down to telling a loosely related story for the sake of entertainment.

Abstraction is essential to scientific inquiry, and often analogy for the sake of one’s own understanding or that of an audience can be a tricky thing to grapple with. All too often when scientists and science writers try to convey especially tricky ideas they end up deviating from their premises and consequently end up communicating something almost wholly different than what they intend to describe.

Over the last few weeks I pointed out a few examples of “exceptional” analogy in science writing. Attentive readers may have noticed they were all sort of… not good. They all fall a bit flat for purposes of communicating the science behind them.. A tough task to be sure, popularisers of science have to balance accuracy against confusing their audience with esoteric nonsense. Wasn’t it Isaac Asimov that said any sufficiently specialised language is indistinguishable from rampant babble? Hopefully you enjoyed the cartoons.

Every single time

This one gets used quite often, and typically will form the pinnacle of a long line of increasingly wayward analogies. Space is mind-bogglingly big (much larger than the distance to the chemist’s, thanks D.A.) and also quite weird.

Don't actually stick your hand in the LHC

I have heard this one from some very clever people. Presumably particle physicists all switched to the rock-star analogy after they grew tired of watching listeners eyes glaze over when they delve into maths.

Mitochondria-The engines of life

Internal combustion in the cell

This one might be the closest to the mark. The engine/mitochondria analogy gets the point across that metabolism involves trade-offs, but does very little to convey a better understanding of the underlying mechanisms.


Philaephilia n. Temporary obsession with logistically important and risky stage of scientific endeavour and cometary rendezvous.

Don’t worry, the condition is entirely transient

Rivalling the 7 minutes of terror as NASA’s Curiosity rover entered the Martian atmosphere, Philae’s descent onto comet 67P/Churyumov-Gerasimenko Wednesday as part of the European Space Agency’s Rosetta mission had the world excited about space again.

Comets don’t have the classic appeal of planets like Mars. The high visibility of Mars missions and moon shots has roots in visions of a Mars covered in seasonal vegetation and full of sexy humans dressed in scraps of leather, and little else. But comets may be much better targets in terms of the scientific benefits. Comets are thought to have added water to early Earth, after the young sun had blasted the substance out to the far reaches of the solar system beyond the realm of the rocky planets. Of course, comets are also of interest for pure novelty: until Philae, humans had never put a machine down on a comet gently. Now the feat has been accomplished three times, albeit a bit awkwardly, with all science instruments surviving two slow bounces and an unplanned landing site. Unfortunate that Philae is limited to only 1.5 hours of sunlight per 12 hour day, but there is some possibility that a last-minute attitude adjustment may have arranged the solar panels a bit more fortuitously.

So if Rosetta’s Philae lander bounced twice, rather than grappling the surface as intended, and landed in a wayward orientation where its solar panels are limited to only 12.5% of nominal sun exposure, how is the mission considered a success?

Most likely, the full significance of the data relayed from Philae via Rosetta will take several months of analysis to uncover. Perhaps some of the experiments will be wholly inconclusive and observational, neither confirming nor denying hypotheses of characteristic structure of comets. For example, it seems unlikely that the MUPUS instrument (i.e. cosmic drill) managed to penetrate a meaningful distance into the comet, and we probably won’t gain much insight concerning the top layers of a comet beyond perhaps a centimetre or so. In contrast, CONSERT may yield unprecedented observations about the interior makeup of a comet.

In science, failures and negative findings are certainly more conclusive, and arguably more preferable, than so-called positive results, despite the selective pressure for the latter in science careers and the lay press. An exception disproves the rule, but a finding in agreement with theory merely “fails to negate” said theory. For example, we now know better than to use nitrocellulose as a vacuum propellant. Lesson learned on that front.

In addition to a something-divided-by-nothing fold increase in knowledge about the specific scenario of attempting a soft landing on a comet, I’d suggest we now know a bit more about the value of autonomy in expeditions where the beck-and-call from mission control to operations obviates real time feedback. Perhaps if Philae had been optimised for adaptability, it would have been able to maintain orientation to the comet surface and give Rosetta and scientists at home a better idea of its (final) resting place after detecting that the touchdown and grapple didn’t go through. Space science is necessarily cautious, but adaptive neural networks and other alternative avenues may prove useful in future missions.

I’ll eagerly await the aftermath, when the experimental and the telemetry data have been further analysed. The kind of space mission where a landing sequence can omit a major step and still have operational success of all scientific instruments on board is the kind of mission that space agencies should focus on. The Rosetta/Philae mission combined key elements of novelty (first soft landing and persistent orbiting of a comet) low cost (comparable to a fewspace shuttle missions), and robustness (grapples didn’t fire, comet bounced and got lost, science still occurred). Perhaps we’ll see continued ventures from international space agencies into novel, science-driven expeditions. Remember, the first scientist on the moon was on the (so far) final manned mission to Luna. Missions in the style of Rosetta may be more effective and valuable on all three of the above points, and are definitely more fundamental in terms of science achieved, than continuous returns to Mars and pushes for manned missions. In a perfect world where space agencies operate in a non-zero sum funding situation along with all the other major challenges faced by human society, we would pursue them all. But realistically, Philae has shown that not only do alternative missions potentially offer more for us to learn in terms ofscience and engineering, but can also enrapture the population in a transcendent endeavour. Don’t stop following the clever madness of humans pursuing their fundamental nature of exploring the universe they live in.

The advantages of parametric design

I work primarily in OpenSCAD when making designs for 3D printing (and 2D designs for lasercutting). This means that instead of a WYSIWYG interface based primarily on using the mouse, my designs are all scripted in a programming language that looks a lot like C. This might seem a bit more difficult at first (and it is certainly less than ideal for some situations) but it makes for a pretty simple way to generate repetitive structural elements in basic flow control, i.e. for loops. Even more important, it means that I can substantially change a design by modifying the variable values passed to a function (called modules in OpenSCAD). For the sake of an example, take Lieberkühn reflectors for macrophotography. Lieberkühn reflectors are a classic illumination technique that have mostly fallen out of style in favour of more modern illumination such as LED or fibre-based lighting, but remains quite elegant and offers a few unique advantages. I have been working with these in conjunction with a few different lenses, and mostly with the help of a macro bellows. The bellows makes for variable working distances as well as magnifications, so the focus of one Lieberkühn will be the most effective only within a narrow range of macro-bellows lengths. Parametric designs such as the ones I create and work with in OpenSCAD allow me to change attributes such as the nominal working distance without starting each design from scratch. For example:


35mm Lieberkühn focus


30mm Lieberkühn focus


25mm Lieberkühn focus


20mm Lieberkühn focus

This approach has proven highly useful for me in terms of both creating highly customisable design and iterating to get fit just right. I’ll post results of my latest exploration of Lieberkühn reflectors soon after I receive the latest realisation in Shapeways bronzed steel.