One of the most discussed topics I see all over the internet, is about this lens being sharper than that lens, etc. and splitting hairs as to which one is 5% sharper.
This may not be the most “exciting” and hip new thing to read or Photoshop trick, but I feel this is very important information for all to know.
I am guilty of this as well, lusting after certain lenses and buying every different lens I could get to achieve the look I had wanted. But it’s a dark road than often leads to nowhere. So why is this a slippery slope?
Because most lenses (I say most, not all) are capable of producing the right quality… however, there are so many other variables. This article by Roger Cicala I found many years ago, really does sum up one of the biggest things regarding sharpness the best (Yes there are other variables, skill level etc., but that’s a different article).
The short version is basically that there are “specs” that the manufacturers abide by, and while a camera and lens might both be “in spec” individually, they might each be at the opposite ends of the “accepted tolerance” and therefore, don’t work well together, since the effective difference is larger than the standalone tolerance spec, but would work fine on a different body and lens.
Roger puts all the details into an easy to understand format, but technical enough that he backs up what he’s saying with the “why,” which is a help with so many skeptics out there.
Lets consider that I have a camera body that is -2 focus units from perfect, and a lens that is +2 focus units from perfect. Both are considered ‘fine’ according to the manufacturer's definition, although they certainly aren’t perfect. However, the combination of a +2 lens on my -2 camera will be absolutely perfect, I’ll love the lens on my camera . After my experience with this one lens on one camera, I will write Sonnets on the various online forums about how great it is, and will tell anyone who doesn’t like it that they must be a bad photographer. I will have become the most dreaded online lifeform, a FLAO (Fanboy with Loss of All Objectivity).
How This Affects the Used Market
Now, this gets really interesting on the massive used gear market, because someone will buy a lens, hate it, and then sell it… Someone else may be wondering, why on earth someone would sell this wonderful lens… the answer may very well be as simple as it wasn't properly calibrated for their body. I hear photographers saying all the time “I just don’t want to buy a used lens because there’s a reason someone was selling it” - Fair enough logic, but there may very well be nothing wrong with it.
As Roger mentions, people are quick to write horrible reviews on a product, much more so, than a good review. We are all guilty of that as well… But before we jump to those conclusions, I really do feel it’s important we have ALL the facts. And worthy of noting, is that as sensors are recording more data than ever, and people are shooting at very wide apertures, this exaggerates any small issue
Now, after all that, it might very well be you have a bad copy of a lens, it happens, but a huge percentage of the time, it’s a mis-diagnosed issue, and we as consumers in general are so quick to wield the power of the internet to slam something.
Note, I really do trust Roger’s opinion more than most folks, simply because in his business, I’d say it’s safe to assume that he deals with more lenses than any of us do, and he would have a good “from experience” knowledge of these things.
Roger followed this article up with some additional data, a few years later: Check it out here.
[via Roger Cicala]