Pentax Quality Control Strikes Again

Started Apr 23, 2015 | Discussions thread
OP Joseph Tainter Forum Pro • Posts: 11,000
Re: Pentax Quality Control Strikes Again
4

Dukhat wrote:

Joseph Tainter wrote:

Gosman wrote:

How do you test for as decentered lens?

Photograph a brick wall with the camera on a tripod. As others pointed out, the camera body must be parallel to the wall. Shoot wide open. For a zoom lens, test across the focal length range. View images onscreen at 100%. Inspect edges and corners for unbalanced weaknesses.

Joe

Joe, are you taking field curvature into account? I'm presuming yes, you seem like one of the more knowledgeable people floating around out there.

Field curvature doesn't matter. I check carefully for side vs. side, top vs. bottom, corners vs. corners for unbalanced weakness. It is lack of symmetry in weakness that tells that one has a lens with optical decentering.

Joe

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