MTF Test Chart – A New Hope

In my previous blog post, I described the quality issues I had with the first MTF test chart printed on Forex. A few weeks later, the replacement paper charts arrived – unfortunately they are also unusable.

Upon closer examination, I noticed that the JPEG compression algorithm (Lanczos-3, in this case) added an outline to the trapezoids used for calculating the modulation transfer function.

Double edge = two bumps on the MTF chart.

Again, much like the lack of edge acutance of the Forex chart, the defect is barely visible to the naked eye, but would influence the lens- and camera test results.

The replacements are already ordered, this time I’ve sent the printer a PDF file instead of a JPEG and I’ve double-checked the edges.

What to do with 100 sheets of high quality prints sized 120x85cm? Well, I’ve got a decent supply of very expensive wrapping paper for the foreseeable future.