Greeting:

I am thinking to run some film/developer tests and would like to include a resolution chart. This chart will be placed in a glass film holder along with a 21 step wedge, and expsed to evenly lit source

Anyone know where I can get one that is about 2x2 inch or smaller? It has to be transmitt type, of course.

Please pardon my Engish. Thanks for all helps.

-- C.J. wong (plainmin@yahoo.com), March 30, 2002

Answers

Whether or not it's still the case, several of these were up for auction on EBay within the last few weeks. They were advertised as U.S. Goverment resolution charts.

-- neil poulsen (neil.fg@att.net), March 30, 2002.

I think what has been appearing on ebay are paper copies of the USAF 1951 test chart. One can also download copies from the internet, e.g., in Postscript, http://www.photo.net/photo/optics/USAF1951.ps. There are also PDF versions. But these won't meet the requirements of C.J. Wong's project, because they are on paper.

The only source I know of for "reasonably" priced high-resolution transmission targets that I know of is Edmund Industrial Optics, http://www.edmundoptics.com/. They sell the USAF 1951 target shrunk to fit on a 2 x 2 inch glass slide. The test slide is made by depositing chromium metal on a glass slide. For $105 one gets a pattern up to 228 line pairs per mm. The "negative" version has an opaque background with tranparent lines. This might not work for C. J. Wong because it is 1.5 mm thick.

Considering the manufacturing technique and the numbers sold, the price is reasonable. If one doesn't want to spend that much money, one could try to make a target by photograhing a paper version onto Kodak Tech Pan. It would make testing more difficult and less comparable with published numbers because the finer patterns would smear some in the do-it-yourself manufacturing process.

-- Michael Briggs (MichaelBriggs@EarthLink.net), March 31, 2002.

Another possible source: Sine Patterns, http://www.sinepatterns.com/. They have glass and film test patterns.

-- Michael Briggs (MichaelBriggs@EarthLink.net), March 31, 2002.