Is lens testing at chart distance really an accurate measure?

Started 2 months ago | Discussions thread
TheGrammarFairy Regular Member • Posts: 360
Are There Any Rules of Thumb?

If a photographer wants to perform a test on a lens to find  the optimal subject-lens distance are there any shortcuts? Or is it just a matter of starting at 30cm from your test chart and moving backward in 30cm increments until you're at infinity.

Or, God help us, do the increments need to be shorter than that?

wrote:

The typical chart size is between 1 and 2 meters wide. If you actually see someone test a 14mm lens on a full-frame camera that way, you might find it comical because the lens is only a few feet (maybe 2) from the chart.

The 30 or 50x focal length rules given in this thread for "infinity" are old and outdated. Modern lenses are very tightly engineered around their applications, a lot of wide angles are terrible close up like the fuji 16/1.4, but just fine focused afar.

It is a "correct" view that data for an object distance of a few ones of feet is only useful to your application at infinity if you drench it in assumptions that may or may not be invalid.

In general, with zoom lenses the more assumptions you make that are favorable to the lens, the further from reality you get.

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