Is lens testing at chart distance really an accurate measure?

Started 2 months ago | Discussions thread
Jack Hogan Veteran Member • Posts: 7,530
Re: Is lens testing at chart distance really an accurate measure?
1

You are correct, it would be best to measure every lens at a few representative distances. However there is a law of diminishing returns so it is typically not necessary to have a chart at infinity: it is said that for most lenses for normal photography a distance of 30X focal length or more is a decent proxy for infinity performance. You are also allowed to move a smaller chart around in the field of view, as some do.

Jack

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