Image sharpness can get a bit “fuzzy”

We photographers have a love-hate relationship to the sharpness of a photograph. It’s not always a conclusion that sharper is always better. Truth be told, the whole subject is a lot more complicated than that.

When photography was in its earliest stages, it startled people for its clarity and sharpness compared to painting. There was no way a painter could produce the same level of detail as found in a contact print of an 8×10 negative, a common print size of the day. So the heritage of photography is tied to the idea of image sharpness, what scientists call a “metric” of photographic quality. That notion continues to this day.

As a result, photographers of all skill levels pay a lot of attention (too much so in some cases) to the quality of lenses and cameras and to the techniques needed to get the sharpest image. Lens manufacturers in particular pursue sharpness as their Holy Grail, and today’s optics are now close to the theoretical limits of light rays passing through optical glass.

There is a whole group of photography enthusiasts who get rather excited by the nuances of various lenses from various manufacturers. They get into heated discussions on various online forums about the merits of this lens or that, and it almost seems as if using lenses to take pictures is secondary. Working professionals, on the other hand, don’t have the time for, or interest in such debates, and will buy and use lenses that get the job done. Such was my attitude in the many years that I relied on taking pictures to make a living.

I intend no critique of amateurs who make lens comparisons a kind of hobby. It’s fun in its own way and I do it myself up to a point. However, I do question the point of it all when it comes to actually making photographs that people want to look at, or pay for.

For instance, I find it almost laughable that the same people who brag about owning their version of the “best of the best” cameras and lenses are taking photographs with a hand-held camera. Doing so will move the camera just enough at exposure to negate any advantage of that lens on an optical bench in a laboratory.

Another optical reality is that lenses reach their sharpest at three or four stops down from full aperture, a point called the diffraction limit, at which point stopping down further only softens the image slightly. At that limit, even simple lens designs of long ago will be quite sharp for practical shooting situations. The modern lens will only show its value because of its superior contrast, flare resistance, or sharpness when used at wide apertures.

I have a small collection of film cameras and using them all has convinced me of this: used carefully, with the lens stopped down a bit, I can’t tell the difference in the final print output up to about a 10X enlargement. The images off my 1950 Rollei Automat look just as sharp as the images off my Hasselblad with Zeiss glass. This is an actual picture-taking result, not a careful test on an optical bench.

Lenses today are generally excellent from a technical point of view. In fact, they are so good that I often find it necessary to “muddle them up” with a touch of diffusion because they can be too revealing of skin flaws, or product defects. There is great irony in seeing the crowds at trade shows gawking at gimmicky lenses designed to produce a blurred image on purpose, or cameras using pinholes or plastic lenses to produce a less-than-perfect image. Meanwhile the booths displaying those elite optics are, well, just so hum-hum.

I think it’s wonderful that we can now assume the general excellence of lens designs; image sharpness is now a given. Still, there is always the temptation to waste time on needless comparisons and debates when we should be out taking pictures.

2 thoughts on “Image sharpness can get a bit “fuzzy”

  1. Quite right – even polycarbonate kit lenses sold with entry level DSLRs are remarkable. There is no excuse ever for not pushing the sutter button!

    Here’s what I find amusing about the sharpness argument: Monet? Degas? Picasso? I think they prove that concept trumps sharpness every time, and technique is no substitute for creative vision.

    How may photographers take razor sharp images – then decimate the image with HDR, then wring them through filters of various kinds?

    Like

  2. Lens design, like a lot of engineering, follows an arc wherein we get great innovation at first, and quality jumps up quickly, but then the changes settle down to small increments.

    Like

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s