lundi 13 décembre 2004

Zoom Lens Effect... or wide-angle trickery? You probably thought the above image had been made with a zoom lens. It certainly looks like that... but in fact it was taken with an ordinary 28mm wide-angle lens. A couple of times I'd noticed similar "motion" images in old copies of Leica Fotografie magazine but was puzzled as to how they could have been made when the photo data indicated a Leica M camera had been used... and there are no zoom lenses for the M-series. Still, we all have certain questions to ask about photography... that's part of the enjoyment of the hobby. I sometimes ask myself, "What will happen if...?" And of course I to try to answer the question for myself... right through to finality... to see if I found an interesting answer. It's interesting to experiment no matter how odd the idea may be... no matter how unlikely it may be that you will end up with a good result... or even a result. And anyway, who knows exactly what a good result is? I knew I was looking for one when I photographed Caro, my flame from many years ago. A good image can be simplicity in itself... it doesn't need expensive equipment or a complex set-up to achieve. Unfortunately more than in any other creative medium photographers have become convinced or persuaded that they actually need a hundred-and-one gadgets to do a hundred-and-one different things. I produced these images by using a typical wide-angle lens which many have on their their camera but few think of using in this way... to create an effect which would normally be produced with a zoom lens. It's an easy technique to do... but it's not so easy to achieve an interesting image every time. I made a number of attempts using different exposure times resulting in two usable negatives from an entire roll of 36 exposures. This may seem a waste of film to some... but it's necessary with such a hit-or-miss technique. The variable factors are shutter speed, lens aperture, lighting level, and the amount of camera movement. Camera movement? Yes, I made the images here by rocking backwards and forwards from the subject whilst the camera shutter was open. So instead of holding my camera steady and using a zoom lens I induced camera motion. Looking through the viewfinder I deduced the most satisfactory shutter speeds would be either 1/2 or 1 whole second. It's necessary to choose a lens aperture allowing one of those speeds or thereabouts... being indoors and shooting in normal room lighting will probably mean stopping the lens aperture down to f/8 or f/11 with a medium speed to fast black-and-white film in the camera. That selection of a slow shutter speed allowed for a camera movement of about two feet. It's important to check beforehand the difference in subject size at each end of your own movement by noting the widest and narrowest fields of view through the camera... which can only be done on a "dry run" with the camera's mirror down allowing uninterrupted viewing. The most important feature - perhaps the model's face - doesn't have to be central in the frame... it can be anywhere within the field of view so long as it receives the least distorting movement when you and the camera move forwards and/or backwards. Overall the distortion is controlled by the distance the camera travels when the shutter is open... and by the focal length of the lens used. It's fairly obvious that a wide-angle lens will produce the most distortion since the image size alters rapidly over quite short distances of travel. So the wider your wide-angle lens the more exaggerated the zoom effect you will produce. By moving or rocking to and fro a few times before each actual exposure is made it's possible to visualise (admittedly fairly abstractly) how the finished image will look. Of course, during a long exposure - and one second is quite a lengthy period of time in photography - the viewfinder of a single lens reflex camera will be blacked out with the mirror up. If that bothers you use a supplementary finder mounted on the camera's accessory shoe. However, to make this exercise much easier than I did at the time... shoot it with a rangefinder camera. Here I used a Nikon F2 with 28mm f/2.8 Nikkor... next time I'll try using my Leica M3 and see exactly what I'm doing throughout the long exposure. Of the two images reproduced here I prefer the more recognisable top one for which a shutter speed of 1/2 sec was used... for the smaller more abstract image I used a 1 second shutter speed. Just one click and one shutter speed setting apart they are visually different enough to press home the point that you have to experiment to get the best, or at least different, results. 7:37:11 PM    comment []