Showing posts from 2015

First LA impressions

I'd actually been in LA very shortly before, but this time I'm with Ana, and I always notice more stuff when I have someone to comment it with (especially her).

I rented a car with Dollar from LAX. I show up at the place, they give me some paperwork and point me towards a row of compact cars. As I am walking towards them, I am trying to find the license plate in the paperwork and fail to do so. I ask which car I am supposed to take and the answer is: anyone I want from that particular section. This is genius. Every single time I rented a car in the past, they gave me the keys in the office and that was it. This way instead I can choose whichever model I want, from the class I paid for. In our case we wanted to have a large trunk, so we got a car that had one, but if we had preferred a more compact car, we could have had that too.Just to get around LA the GPS inevitably directs you to a bunch of roads that are famous from movies (often movie titles). Sunset Boulevard, Mulholland…

A consistent measurement system for photography

Everybody who starts with photography must eventually come to grapple with f/numbers, shutter settings, focal lengths and ISO values. The problem with the current system is that they are all on different measurement systems. Focal length and ISO are linear, shutter speeds are expressed as fractions, and apertures are proportional to the square root of the amount of light.

The end result of these different scales is that the actual values are just about useless for any practical calculation a photographer might need to do.

For example let's say that you are wondering what ISO you will need to photograph a stationary object lit by streetlights, using a 28mm f/2.8 on a full frame DSLR. Street lighting is usually around 15 lux, which is about LV 2. LV 0 is defined as the amount of light that requires 1 second exposure at f/1 and ISO 100, and LV 2 is two stops brighter than that. Let's see, f/2.8 is - f/1,  f/1.4, f/2, f/2.8... Three stops darker than f/1.  Three minus two is one, …

Nikon AF-S NIKKOR 28-300mm f/3.5-5.6G ED VR Lens Review

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 …

Was any other car company gaming emission standards?

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 …

Why can't consumers buy fuel futures?

The average american family consumed about 4% to 6% of pre-tax income on gasoline, which probably means about 7% to 10% of after tax income. After you factor in mortgage payments, insurance copayments and other fixed expenses, I'm guessing that a lot of families give their local gas station about a fifth of their monthly cash in hand. Given that in the short run consumers are stuck with the car, workplace and home that they have, short run price elasticity of gasoline is famously low, or around -0.25 (for non-economists: that means a 10% increase in gas prices reduces consumption by only 2.5%). As the graph above shows, between 2002 and 2008, increases in the price of gasoline ate over  $1,500 from the budget of the average US family. Gasoline price volatility is thus a major source of risk to the finances of US families.

It is therefore surprising that a prudent consumer in the US (or in any other country I'm aware of) has essentially no ability to protect himself from the r…

How to take dramatically lit landscape on boring light days

Here's a fun technique. I think it's new, but if somebody else has already done this or something similar, please feel free to correct me. The technique allows you to simulate very directional lighting even on days with so-so lighting, but it does take a little bit of planning.

Let's say you're out and about shooting photos, and there's a light overcast/mixed cloudy sky. If you wait until a break in the clouds hits your subject, you can take photos like this one:

Decent, but nothing too spectacular. How could you make the lighting more dramatic? One option would be to mess around with levels or curves, but that's going lead to clipping of highlights and/or shadows, pretty soon. Like so:

So here's my idea. First you wait until the clouds move a bit and your subject is in shade. Then you take a SUPER boring picture like this one from exactly the same camera position. This photo has completely diffuse lighting and next to know threedimentionality:

How does t…

The real stakes of the Greek vote

The Greeks should stop being so selfish. Why are they voting on this referendum based on what they think will be best for their economy? Don't they understand how their vote will impact legions of armchair (or chaired) economists and political scientists?
Let's say they vote yes, accept the northern european ultimatum, and Greek society proves resilient enough to muddle through the cuts and austerity. Great. They will have conceded to the neoconservative enemy the last bastion of left-wing orthodoxy left in the Northern/Western hemispheres. They will have on their hands the conversational blood of millions of wearers of Che Guevara t-shirts,  local organizers of italian Feste Dell'Unità, and pretty much the entirety of french society without a hungarian last name.
If instead they vote no, and reject Das Deutsche Diktat, they could recklessly end up understanding the incredible luck they just had, clean up their act, and push through the much needed reforms. In one stroke, …

The advantage of having good research assistants

Oh, wouldn't it be great to have RA's that find stray pages from government accounts and bring them to you? From Ibn Khaldun, discussing how judges and priests generally don't become rich (emphasis added).

I discussed this with an excellent man. He disagreed with me about it. But some stray leaves from the account books of the government offices in the palace of al-Ma'mun came into my hand. They gave a good deal of information about income and expenditures at that time. Among the things I noticed, were the salaries of judges, prayer leaders, and muezzins. I called the attention of (the person mentioned) to it, and he realized that what I had said was correct. He became a convert to (my opinion), and we were both astonished at the secret ways of God with regard to His creation and His wise (planning) concerning His worlds.

Now, that's a disclaimer paragraph!

How many times have you looked at the bottom of the first page of an economics paper, and read something like "we would like to thank X, Y, and Z for useful comments and corrections. All remaining mistakes are our own", where X, Y and Z are well known scholars, usually named in decreasing order citation count.
Well, step back and let 14th century polymath Ibn Khaldun show you how its done:
In a way, at-Turtushi aimed at the right idea, but did not hit it. He did not realize his intention or exhaust his problems.  We, on the other hand, were inspired by God. He led us to a science whose truth we ruthlessly set forth. If I have succeeded in presenting the problems of (this science) exhaustively and in showing how it differs in its various aspects and characteristics from all other crafts, this is due to divine guidance. If, on the other hand, I have omitted some point, or if the problems of (this science) have got confused with something else, the task of correcting remains f…

The Haldeman Moment

H.R. Haldeman was the White House Chief of Staff for President Nixon. As the Watergate/Pentagon Papers scandal was slowly unfolding, he at one point tried to explain how the revelations damaged the administration. In doing so, he accidentally composed the most damning accusation of his own administration's wrongdoing:
"But out of the gobbledygook, comes a very clear thing: you can’t trust the government; you can’t believe what they say; and you can’t rely on their judgment; and the implicit infallibility of presidents, which has been an accepted thing in America, is badly hurt by this, because it shows that people do things the president wants to do even though it’s wrong, and the president can be wrong."  If anybody has done a better job of summarizing the failures of the Nixon administration in five lines or less, I am not aware of it. Though of course, the best summary in five WORDS or less was given by Nixon's famous one-liner:
"I am not a crook! Which, even…