It is well known that two lenses of the same focal length but with a one (or even 2/3) stop difference in maximum aperture will differ greatly in price and mass. This fact was highlighted by Nikon's recent release of a modestly priced 200-500 f/5.6 priced at one fifth of the 200-400 f/4 and about 1.3 kg less mass. One may make all sorts of arguments in favor of the more expensive item but in reality will it really get that many more great photos than the already very good 200-500 which has range and handling advantages? The same analysis applies to Nikon's excellent short primes, available in both f/1.8 and f/1.4 flavors. Reduced depth of field is an often cited advantage of wider apertures but while shooting my 50 f/1.4 G (the least exotic of all f/1.4, 50mm or so lenses) at f/1.4 I have noticed the DOF is too thin for how I shoot. F/1.8 to f/2.2 works best.
In Mexico I met another gringo who was shooting a D3. He was saving up to buy a 200-400 and was an employee of the US government in Washington DC. My first observation was he was not wealthy or a pro, but he chose to spend twice on a D3 what my D700 had cost. The second observation was my personal philosophy is if you have to save up for something like that, you probably can't afford it. OK, he and I both live in a free country where we can make these choices, but somehow I felt he was off course and letting his life be ruled by and uncontrollable desire for material things. We have all heard of this. It's NAS, GAS and so on. Will your life really be better if you shell out big bucks for an exotic fast telephoto a 24mm f/1.4 or a Zeiss Otus? In one forum some guy celebrated his purchase of a new 300 f/2.8 to photograph his 6 year old's soccer games. I am certain those photos will be better than if a simple 70-300 had been used. The boy will probably have to borrow an additional $15,000 to get through college because his dad did not put away $5000 in and S&P 500 index fund. If the father's behavior persists across other potentially expensive activities it might be the difference between being able to pay for his son's education and his son being heavily in debt at age 22. Student debt is rampant in the US. Again, this is more a matter of values than of image quality.
There is a growing school of economists who believe in confiscatory taxes on the wealthy with redistribution to middle class citizens as well as the poor will stimulate the economy through consumer spending. There are people who think we should eat crickets because the money spent on meat could be used to end hunger and less CO2 would be generated. A Nobel prize winning economist tells us making more than $75,000 per year will not make you any happier. He won the prize for some other work which is very signifiant if you know anything about economics. None the less economics is the study of how people behave. It's a social science subject to manipulation by those who are trying to justify a certain social result.
One last bit. I believe Nikon is bringing out products like the 200-500 and f/1.8 primes to keep full frame DSLR photography relevant to a wider audience, not just those with deep pockets or incurable NAS.
