Lens test 50 Full tilt Find out what tilt-shift lenses can bring to your photography and which one of three 24mm models from Canon, Nikon and Samyang comes out on top…
Photography News Issue 29 absolutephoto.com
Tilt-shift jargon buster
Tilt – angling the lens vertically Depth-of-field is formed either side of the plane of focus and the latter normally sits flat-on to the camera. But when tilt is applied, the plane of focus is pitched forward or backwards, with the depth-of-field still extending either side. So, if you imagine a regular plane of focus looking like a rectangle, a tilted plane looks more like a wedge, and that extends the depth-of-field possible.
Swing – angling the lens horizontally
This is the same principal as tilt, but with the plane of focus angled sideways rather than forwards or backwards. Therefore it’s useful if you want to bring a line of trees or the side of a building into complete focus. Using the mount rotation control, the angle of tilt can be further modified, for instance at 30º to the level.
Rise and fall – pushing the lens up or down Using the shift function you can move the lens at right angles to the optical axis, and that means you can avoid tilting the camera back when composing, therefore eliminating converging verticals. This function also allows easier image stitching, as the camera doesn’t need to be moved between exposures.
Shift – pushing the lens to the left or right The ability to move the lens horizontally means you can shoot exposures for a panoramic stitch more easily as you don’t need to move the camera. Shift can also be used to alter the composition without moving the camera, for instance to avoid an obstruction, or when you want to remove the reflection of the camera when shooting glass or mirrored subjects.
photography; they’re not going anywhere. Tilting and shifting can also cause changes in colour, so shooting in Raw is a good idea, wherewhite-balance is easily editable. The main benefits of a tilt-shift lens are the ability to achieve perfect front-to-back sharpness, and to control errors like converging vertical lines. While you might usually shoot at f/16 or above to get greater depth-of-field, smaller apertures cause diffraction, so while the depth-of- field is greater, quality is lower. In contrast, a tilt-shift lens lets you use the apertures that give the sharpest results, usually between f/5.6 and f/11, and still extend the depth- of-field to infinity. This works by tilting the lens so that the plane of focus becomes angled; on a traditional lens the plane of focus is flat-on to the camera with the depth-of- field extending in front and behind it; but when it’s tilted the plane can follow the landscape and therefore even large apertures can keep a scene in focus. This needs to be carefully directed, as, with the plane of focus ‘pushed over’ you’ll find the bottom of a subject might be in focus, while the top is blurred. That, in part, is where the miniature model look comes from. When it comes to converging verticals, you’ll find them in all sorts of shots, and they’re produced when you angle the camera up or down at the subject. To avoid them the camera has to remain level, which limits your framing options; but to fix the issue, a tilt shift lens’s ‘shift’ function allows you tomove the lens upwards. Another benefit of tilt-shift lenses is in using the shift function to shoot images for apanoramic or stitched image. Once again thanks to the larger image circle produced you can simply push the lens left or right of centre (or up or down), and the images will align without the need for complex movements of the camera or a panoramic tripod head. Now read on to see how three 24mm perspective control lenses fromCanon, Nikon and Samyang fared... Above Tilt-shift lenses have become synonymous withminiature style views, and this comes from their ability to angle (tilt) the plane of focus. However, tilting also lets you achieve perfect front-to-back sharpness, which is arguablymore useful. The shift function is used to correct converging vertical lines (left), avoid reflections and for panoramic stitching.
ReviewbyKingsley Singleton
Below The same scene shot at f/11
An Internet search for ‘tilt-shift lens’ will turn up lots of images that look like scale models shot with macro lenses. Of course, these are real scenes made to look tiny thanks to the unique properties of tilt-shift lenses. These pics are often brilliant, but fun as they are, they’re not really what tilt-shift lenses were designed for. In fact, their original purpose was to make scenes look more lifelike, not less. The real benefits are the ability to reduce perspective distortions and/or achieve perfect front-to-back focus. Tilt-shift lenses offer a feature regular lenses do not; moving the lens independently of the filmplane, or sensor; essentially the same as an old view camera. What this means in practice is that you can tilt the lens up, down, left or right, as well as shifting it in those same directions, while the camera stays in the same position. All these features are possible because tilt-shift lenses produce a much larger image circle than normal optics. For example, a regular 24mm lens will produce a circle of light just a little larger than the sensor of the camera it’s designed for; but a 24mm tilt-shift lens produces a much larger circle – about 50% greater in volume – so it can be moved aroundwithout immediately vignetting. There are drawbacks; mainly that tilt-shift lenses must be focused manually, and that exposure is often manual too (although two of the lenses tested allow autoexposure, tilting or shifting can throw the metering off). However, with live view focusing (as explained in this month’s Camera Class) and using the camera’s exposure bar, these factors don’t need to be problem. Exposing and focusing manually will, of course, slow you down, but that’s not a problemwith the kind of subjects you’ll be shootingwith a tilt-shift lens; landscapes, architecture, still-life or product
with a regular 24mm lens, andwith a tilted 24mm lens, showing the greater sharpness.
Tilted lens
Regular lens
Tilted lens
Regular lens
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