Good enough, revisited

Roger Cicala of LensRentals has posted some test results on zoom vs prime lenses. It turns out that, in general, zooms are not as good as primes.

Is anybody surprised?

Apparently so. There has been some Chicken Little conversations on the web in response. I don’t see what the fuss is about. Yes, zoom lenses have gotten much better over the years, and at a faster rate than primes. No, they haven’t caught up. I don’t expect them to do so in my lifetime. 

But here’s what’s changed, and all the tests that show zoom lens deficiencies won’t affect this: the best zoom lenses are good enough for more and more things. They are sharper, have lower distortion, and have less flare than they used to. They’re even getting a bit faster, in some cases (thank you, Sigma).  But the pages in magazines (those that are left) aren’t getting bigger (although the resolution is creeping up slowly). The size of people’s wall is not increasing dramatically (although it’s much easier to make big prints than it used to be). The resolution of displays is increasing, too, but it’s still behind what you need for a good 16×20 print by quite a lot. 

So what’s happened, and is happening, is that zoom lenses are appropriate tools for more and more photographic uses. In fact, they are so good at many of those things that many of their users are unaware of their limitations — although they are there if you look hard enough, they simply don’t affect many people. Out of sight, out of mind, out of existence; that’s the thinking chain that gets people saying that zooms are as good as primes. But for many purposes, you won’t see any material difference in the images made with zooms and primes, and why shouldn’t people who plan to put no greater demads on their photographs be denied the undeniable advantages of using zooms?

The above line of thinking get me started on other places where similar situations exist. I didn’t have to look far. Sensor resolution, for example. If you want maximum flexibility, more is better, and we have a long way to go before increased resolution will yield no visible improvements with the best current lenses, under the right conditions. But most people don’t use the best lenses there are (see above zoom discussion). And most people using interchangeable lens cameras don’t need anything beyond 24 MP, or maybe 12 MP. For them, the latest set of resolution improvements we’ve seen, and the ones that we will see soon, will bring no useful advantage, and some usability impairments unless they happen to have top-flight computer systems. 

Dynamic range is another case in point. When digital capture became mainstream, most cameras couldn’t come close to the eight or nine stops demanded by normal Zone System development. Now even MFT cameras can do that easily. Even the greater dynamic range of C-41 negative film is routinely exceeded by the current flock of full frame cameras. Many, if not most of us have plenty of dynamic range already. What do we need more for? 

There is danger here that the universe of people who care enough about improvements in all these areas (and some I haven’t thought of or bothered to mention) will grow smaller and smaller until it’s not worth it for camera manufacturers to continue to work on raising image quality, but turn their attention exclusively towards size, weight, automation, and ease of use. Don’t think it can’t happen. MP3, Sirius, Pandora, and other compressed audio formats satisfied a large enough audience that high fidelity audio is on life support. Cell phones have put point and shoot cameras on the endangered species list, and they’re coming after interchangeable lens cameras someday soon. 

For the people whose needs will be satisfied with cheaper, smaller, more integrated, and easier-to-use camera gear, all this will be a good thing. For those of us who pursue high-quality printed images, not so much.

By the way, I notice that I wrestled with this topic about 6 years ago. I was in a more optimistic frame of mind then.