Silverbased

Occasionally some self-appointed guardian of language purity will scold photographers that they’re misusing the word telephoto.

It is true that in optical design, the term “telephoto” originally had a specific technical meaning. Through the use of a negative component closest to the film, the overall length of a lens can be reduced, so it becomes shorter than its optical focal length.

Rear negative element makes this Zeiss design a true telephoto

The purist would have us refer to longer focal lengths lacking this special configuration as long focus lenses. The distinction can be relevant for view-camera users, because it affects the bellows extension required to focus. But should the rest of us become angst-ridden about using the “wrong” word?

Recently I’ve been reading Rudolf Kingslake’s A History of the Photographic Lens. He makes a few interesting observations about telephoto lenses.

The size reduction of true telephotos becomes increasingly valuable the longer the focal length required; however they demand careful design to avoid pincushion distortion. A classic telephoto configuration can yield a lens that is physically about 80% as long as its focal length—called its “telephoto ratio.”

Yet a mirror lens using a folded light path can do even better: its physical length can be less than one quarter of its focal length. With such impressive telephoto ratios, don’t these designs also deserve the name?

The lenses for 16mm or 8mm cine cameras cover a small film format; accordingly, their focal lengths are proportionately shorter. In the days before zoom lenses became ubiquitous, movie-makers would switch between individual wide, normal and telephoto lenses. Yet because of their shorter focal lengths, cine “telephotos” rarely needed to be true telephoto designs.

Yet the term telephoto has been firmly entrenched in movie usage for at least 50 years. Thus, the zoom controls for subsequent cine cameras were labeled “wide—tele” and not “wide—long.” And of course this convention was carried forward to all motorized zooms in point-n-shoot still cameras, whatever their optical designs.

Another problem with this fussbudget distinction about telephoto is that most of us don’t know the exact optical configuration of the lenses we use—and have no reason to care.

A curious example of this is the Olympus XA, which includes a 35mm f/2.8 lens. Any sane standard would regard this as a moderate wide-angle. Yet in fact, the XA’s optical design is a true telephoto—using a large negative element close to the film, to permit the camera’s impressively compact clamshell body. (Kingslake cites the Kodak Disc Camera lens as a similar example, although the XA design preceded it.)

Would the pedants insist we call the XA a telephoto camera?

In its official literature, Olympus listed my beloved OM-System Zuiko 85mm f/2.0 alongside other telephotos, while noting its telephoto ratio as 108%. In other words, it’s not a true telephoto at all—it’s merely shorter than competing brands. (In a cross-sectional diagram, its rear lens group appears to be positive.)

Zuiko 85mm: Too tall for tele?

Today of course, zoom lenses are ubiquitous on all types of cameras. It’s rarely clear how to pigeonhole their complex optical designs. (Canon’s basic DSLR kit zoom uses 11 lens elements.) Should we name the long end of their zoom range telephoto or not?

Photographers will always need SOME term to describe a narrower-than-normal field of view; or equivalently, focal lengths longer than the image diagonal. And at this late date, telephoto has become the term most universally understood.

Steven Jay Gould once wrote a column in Natural History, “Bully for Brontosaurus” (which lent its name to a book collection of essays). In it, he bemoaned the 1970s nomenclature revision in paleontology which (on narrow grounds of priority) replaced the familiar name brontosaurus with apatasaurus instead.

Not only did he find the reasons for the change questionable; but he also felt that the brontosaurus—as one of the “rock star” dinosaurs—had done much to fuel public interest in his field. So he encouraged his readers to continue using the old name, without guilt.

In the same spirit, I say “bully for telephoto.” Unless you design lenses for a living, ignore the finger wagging of prune-faced killjoys. Use the word telephoto freely, and be happy.

And remember, the images you take with your lenses are more important than the names you use for them.