As most of you already know, Volkswagen was recently caught cheating on emission tests. But were they really alone in doing so? The EPA data shows some suspicious patterns.
Without getting too technical (in any case, the specifics are still unclear), there's a tradeoff between fuel efficiency, and NOx emissions. So for a given level of performance, the software that controls a modern diesel engine can be tuned so that it is more fuel efficient, but produces more NOx, or it can be tuned so that it is less fuel efficient, but produces less NOx.
Since Volkswagen had problems meeting the NOx standards in the US, they decided to introduce software that detected when an emission test was being performed, and tuned the engine so as to decrease NOx production, in the process potentially worsening fuel economy relative to regular driving conditions.
One possible outcome of this procedure is that the cars involved might actually have better fuel economy in real life conditions, than during …
One of my ongoing research projects is on the Mongol invasions. Doing some background research, I realized there's an interesting asymmetry between male and female rulers, in terms of available imperial sexual strategies.
Say that the Mongol hordes have just finished annexing another city along their ever expanding frontier. Let's call it Elbonia. In this case the local elite had the good sense to surrender peacefully, and accept the Mongols as their rightful overlords. Everybody knew that if they put up a fight, the Mongols would typically exterminate a significant proportion of the local population, and enslave the rest.
What did the Mongols want from Elbonia? Well first of all, obviously they didn't want the inhabitants to ever attack their other dominions, regardless of any preexisting local feuds which may have existed. Secondly, they wanted them to send them money or tradable goods regularly. And thirdly, they wanted them to furnish soldiers for use in their next cam…
I just upgraded from a D90 to a D750, and I decided to buy a superzoom to use when I don't want to carry around the full bag of primes. It was a tossup between the 24-120 and the 28-300, but in the end I picked the latter since I already had a 24mm f/2.8D which had been collecting dust during my decade of using DX-sized sensors. In fact I might trade the 24mm with a 20mm if the opportunity comes along.
Anyway, there's a lot of controversy surrounding this lens, so I thought I would make some tests to decide whether to keep the lens or not, and since I have them, I figured I'd post them online.
So here they are. The first one are 200x200pixel crops (roughly) from the center of a resolution target. I took every marked focal length, and every full stop of aperture. I put a green dot next to the combinations that I considered satisfactory. For comparison, the "Optimal" square was obtained by taking a photo much larger version of the same pattern and scaling it down …