Ricoh GR III Camera Review


Distortion refers to the capability of a lens to represent straight lines as...straight lines. Wide angle lenses often create barrel distortion, where lines look they've been put on a sphere. Telephoto lenses can create the reverse effect, named pincushion distortion. The following images illustrate the various types of distortion:

Barrel distortion, left; no distortion, center; pincushion distortion, rightBarrel distortion, left; no distortion, center; pincushion distortion, right

It is very difficult to create a zoom without some distortion. It is also very hard to design a wide lens, even a prime, which is distortion-free. On the other hand, normal and short tele lenses can more easily avoid the problem.

The way to evaluate distortion is pretty straightforward: take a picture of straight regular lines, and look if they curve. Calculating the ratio of curvature yields an evaluation of distortion.

DSLRs often offer the ability to automatically correct lens distortion. This feature can be turned on or off at will. With the GR III, there is no such control, though we will venture to guess that Ricoh did build this correction into the camera. With a non-removable lens, this is to be expected.

Distortion Test results

The following images show how the distortion pattern looks when photographed with the GR III.

The amount of distortion is negligible, at 0.3%. It should have no effect in actual shooting conditions. 


At 0.3%, distortion is negligible with the Ricoh GR III. PentaxForums @PentaxForums News | Reviews | Forum

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