So I saw rd95 post this video this morning about questioning the practical differences between cheap and expensive photography lenses. Unsurprisingly, he couldn't tell the difference, and neither could the "pros" in their video. Having spent several years as professional product photographer using a wide variety of lenses, from cheap kits to primes, my experience doesn't necessarily match their conclusions. Granted, technical product photography is much closer to "shooting a focus chart" than shooting some art film, or a cinéma vérité documentary or especially your kid's birthday party, but when you need to get 30 megapixels of toothbrush every millimeter of lost focus is a reduction in final resolution and every chromatic aberration is going to take at least (if you're lucky) a few more minutes in post to fix, the differences in lenses become more apparent.

Like the guy near the end says, the quality of the lens only become apparent under the most extreme circumstances; when your aperture is wide open or completely stopped down will the differences focal quality and range, and color accuracy be most apparent. Furthermore, in a day and age where we like to apply chintzy Instagram filters on our pictures to give them some kind of historicity, shooting with anything more than the most basic lens is laughable. Also, traditional film is much less forgiving than digital since you have so much freedom in a digital post environment to change and fix things.

The idea that we can all sit here and see some sort of obvious difference between the lenses over a youtube video is rather silly; sure you can pretend that using a 4k camera and watching the results on a 1080p TV is somehow "exercising" the lens, but it's really not. 1080p is the equivalent of 2 megapixels, and 4k cameras shoot at a little over 8 megapixels, while a good medium format DLSR will shoot with 50 megapixels and large format film can be scanned at 100-200 megapixels. Truth be told, the differences are usually only obvious when seen under a loupe, and when shooting under extreme conditions or with technical limitations. What that means is, yes, you get diminishing returns for increasing investments in your glass, and for 99% of consumer applications, and even 95% of professional applications, low to mid grade lenses are more than adequate.

Ultimately, people like to compare brand names as a measure of their self-worth and it's fun to think about what you're capable of instead of what you're likely to actually do, and those are the people who are most irrationally draw to expensive lenses as a form of conspicuous consumption. The real secret here is to buy a good quality used lenses (from a reputable dealer, of course). Unlike camera body/sensor technology, lens technology has changed minimally over the years. You can get a much better bang for your buck from a place like keh.com than you ever will shopping new.

In conclusion, it's like putting two thousand dollars worth of racing tires on my Accord, driving down to the store and remarking "Gee, these fancy tires don't feel any different than my old Michelins!" when in reality, not only do you need to be on a track to see the difference, you also need a particular caliber of car, skill of driver, and maybe even a skid-pad and lateral-g accelerometer to fully see the difference.