Though most modern lenses are of very high standards, especially the pricey, top of the line series from major manufacturers, the very high level of precision demanded by architectural photography dictates that only the best of the best passes the stringent guidelines.
All lenses intended to be used in architectural photography should be tested critically for any distortions.
What is Curvilinear Distortion?
Curvilinear distortion is the curving of straight lines in an image caused by uneven magnification in the lens. It occurs more towards the edges of the image. There are two major types of curvilinear distortions namely barrel distortion and pincushion distortion.
What is Barrel Distortion?
|barrel distortion of camera lens|
Barrel distortion is associated with wide angle lenses and typically occurs at the wide end of a zoom lens. It causes images to be spherical or "inflated" and is most visible in images with perfectly straight lines, especially when they are close to the edge of the image frame. The use of converters often amplifies Barrel distortion.
What is Pincushion Distortion?
|pin cushion distortion of camera lens|
Pincushion distortion is associated with tele lenses and typically occurs at the tele end of a zoom lens. It causes images to appear as if pinched at their center. Similar to barrel distortion, pin cushion distortion is also most visible in images with perfectly straight lines, especially when they are close to the edge of the image frame. The use of converters often amplifies Pincushion distortion.
As we are mainly interested in Architectural photography, our greatest concern is the barrel distortion of wide-angle lenses that we commonly use. In the next article we will discuss how to practically check lenses for distortions.