View Full Version : people photography: telephoto vs standard design

David Carson
26-Jun-2007, 08:12
I've read the info on the uses of telephoto lenses (for reduced bellows draw) and their disadvantages, but here's a question I haven't seen:

For people photography (no movements) and two same focal lenses, same aperture, same size of subject on the film, only with one tele, the other one standard, is there a different 'look' to the photographs?

I'm thinking of compression, bokeh, I dunno, the 'look.' :)

Donald Qualls
26-Jun-2007, 10:20
There's usually a very, very small difference in image quality between two images made with the same lens, but one using a teleconverter (which is effectively what a telephoto is -- a shorter lens with built-in teleconverter). The more glass surfaces, the more sources there are for scatter, and even with modern coatings more elements means some loss of contrast; there are also more sources of random errors in the surfaces, so you will sometimes see extremely subtle loss of sharpness with more elements (and a tele will generally have *at least* two more elements than a conventional lens the same focal length).

Offsetting that is the fact that the camera is less prone to bouncing on the tripod with the shorter draw a tele permits -- the mass isn't on such a long arm, so vibration will damp more quickly and may have less effect on the image.

Overall, if the camera can handle the longer draw needed by the conventional lens, I'd expect to see an *extremely* subtle advantage in image quality over the tele -- and there's one major advantage: the conventional is almost certain to be less expensive, likely to be faster as well (which means the ground glass is brighter and focusing is easier).

Ken Lee
26-Jun-2007, 11:57
I presume that Telephoto lenses come in a variety of designs, just as standard lenses do.

So the comparison might become: which Tele design, against which standard design ?

Ole Tjugen
26-Jun-2007, 12:29
The assumption that tele lenses have more elements and/or more groups than "normal" lenses is unfortunately not valid: http://www.schneiderkreuznach.com/archiv/pdf/tele_arton_tele_xenar.pdf shows the design of two typical examples, Tele-Xenar and Tele-Arton.

The assumption that tele lenses will be less prone to bouncing is also not valid, for two reasons:

The lens itself extends a long way in front of the lens board, so even if the tripod-mount to lens is shorter, the front standard to center of mass is longer.

This also implies that a tele lens will be more prone to rotational vibration - pivoting around the mounting point more than a straight up-and-down bounce. The concequence of this is negligible with "normal" lenses where the pivot point would be close to the lens node. But a tele lens has the node far in front of the pivot point, often a distance in front of the entire lens. So that rotational vibration suddenly has a BIG impact!

Being utterly unsymmetric, tele lenses are often less well corrected for distortion than other more symmetrical lenses.

Trying to use swings and tilts with a tele lens is a quick way to a headache - either that, or a deep understanding of tele lens physics.

For portraits they should be about equivalent. But I wouldn't recommend a tele lens unless you really need it for some other reason (i.e. bellows draw).

Ken Lee
26-Jun-2007, 13:17
I would be surpised if View Camera movements were never used in portraits. View cameras let you face the subject straight on, but adjust the centering of the subject without introducing any distortion.

For example, in this image (http://www.kenleegallery.com/html/portraits/g0806.htm), the camera was located at the level of the dog's faces, so we "look upwards" while keeping the back perpendicular to the ground. That's why you can see the underside of the people's noses and chins, even though we are looking straight ahead.

By not tilting the back upwards, the stairway in which they were sitting, did not suffer from converging lines, and the people did not end up looking like... cone-heads. Having some extra coverage was vital.

David Carson
26-Jun-2007, 13:51
Thanks for all your replies!

26-Jun-2007, 14:34
It don't make no difference. Nohow.

David Millard
26-Jun-2007, 18:53
The only view camera movements that are more challenging with telephoto lenses are front swing and tilt; front shift and rise, along with all rear movements, are not an issue.