Is lens testing at chart distance really an accurate measure?

Started 2 months ago | Discussions thread
Bernard Delley Senior Member • Posts: 1,494
Re: It may depend on your needs...

Erik Kaffehr wrote:

I don't think charts are useful for testing. To begin with, they need to be flat and well aligned to camera sensor.

If you want to check out a lens, I would recommend Jim Kasson's Lens screening test:

If you want more quantitative testing, it may make some sense to replace Jim's 'Siemens star' with slanted wedges for MTF testing.

I like the quantitative results from chart MTF testing. I think it is worth the extra effort. It is mostly an initial effort learning to set up and analyze properly.

In any case, the real challenge is how to return an obviously sub-par lens without incurring excessive costs. Did you ever return a brand new lens ? Returning the lens, which I mentioned before, cost me 16% of the lens price. Probably a fair cost. However, I did not wish to try more lens samples of this model. -- I wonder what the shop does with the returned lens, which looks perfect by eyeball inspection.

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