A lens which has a combined tilt and shift movement is called a tilt-shift lens. Tilt-shift lens produce sharper image when compared to other regular lenses. They allow a photographer to use depth of field (DOF) and perspective more creatively. These lenses are used in architectural and landscape photography. Tilt-shift lenses are also used very effectively for creating a panorama or a miniature version of any life size subject. When both tilt and shift actions are used in a single image, the resulting image gives greater control.
Tilt action of the lens lets the lens move at an angle towards up or down with respect to the camera sensor, which allows the plane of sharpest focus to move away from the perpendicular plane of the lens axis. It results in the increased width of depth of field with increased distance from the camera.
Tilt movement is used to increase the apparent depth of field of an image at wide apertures. It allows the photographer to take images in different planes which are sharp throughout. Tilt movement of the lens lets the photographer control the plane of movement independently from the camera aperture.
Tilt action also produces wedge shaped depth of field which means that the depth of field in the image remains very narrow but it extends up to infinity. Hence, a part of the image which is perpendicular to the line of sight remains in focus.
Another creative use of tilt action can be seen in miniaturizing a subject. When the tilt action is applied in the plane opposite to that of the subject, it produces the miniaturizing effect. In this composition, the depth of field reduces when the shot is taken from above the subject plane. The reduced depth of field gives the effect of reduced subject size which further produces the scaled sized miniature objects in the image.
In shift action, the camera lens moves sideways with respect to the camera sensor in such a way that the center of the image perspective changes when compared to the center of the lens perspective.
Shift movements of a tilt-shift lens allow photographers to alter the perspective and expand the viewing angle. When tilt shift lenses are used in normal conditions, they produce sharper edges of the images when compared to other lenses. These lenses also produce less ‘vignetting’ effect around the edges of the frame. A tilt-shift lens creates a larger image circle when compared to a normal lens. When the image sensor does the cropping of the image in a rectangular area, the edges and corners of the image remain relatively sharper.
Using shift movement of the lens, the perspective of the subjects can be set right. Use of wide angle lens while clicking a tall building from a short distance makes either the top of the building look converging or the building appears as if falling down on one side. The shift movement by altering perspective makes the building look straight from a very short distance. Shift action can be used to create incredibly high resolution images with almost double pixel counts. It also gives the photographer a wide angle lens image with sharper corners as compared to an image taken with a wide angle lens.
Another advantage of using a tilt shift lens is while creating a panorama. The shift action of the lens allows the photographer to take three shots without changing the camera position: one from left of the center position, one at the center position and one from right of the center position in the same horizontal plane. For a vertical panorama you just have to switch to portrait mode. The images taken from tilt-shift lens are of the same horizontal or vertical plane and the image editing software tools merge them coherently.
Many effects of tilt-shift lens can also be reproduced using the post-production software tools. The ‘keystoning’ effect in which the tall buildings appear falling down can be corrected using the lens correction tool of Photoshop. Similarly, a panorama can also be created using the post-production tools with images taken from regular lenses. The tilt-shift lens makes these processes seamless and easy to achieve. The disadvantage of using tilt-shift lens to create a panorama is that the number of images is limited to just three. However, in order to shoot more than three images, you need to change the camera position or make use of the panning movement of your tripod.
The miniaturizing effect produced by tilt-shift which appears artistic can also be created in post-production. The cost effectiveness of a tilt-shift lens becomes the most important factor while buying this lens to do the things which can be done using other less expensive lenses and a post-production software tool.