Lens Resolution Test Target

(work in progress 15 April 2005)

The standard ISO 12233 chart cost $150 in its smallest size. A more practical 4X size is over $600. A PDF version of the chart is available at

http://www.graphics.cornell.edu/%7Ewestin/misc/res-chart.html

The problem becomes how to print it precise enough to have any meaning. At 1:1 1200 DPI laser printers just do not get the job done.

I came up with another idea for a subjective comparison. For my purposes I decided to compare all other lenses to a Pentax-A 50mm f/1.7 at 5 feet. I did some calcs to find out what the proper size was for the *ist (apps) sensor with a 50mm lens at five feet. That comes out to a little less than 20 x 30 inches and works out well for mounting on a standard size piece of foam board.

The size makes it easy to determine the exact distance from the target for testing: 18mm = 1.8 feet, 50 mm= 5 feet, 300mm = 30 feet, etc. These distances also tend to fall within the focal ranges of various lenses.

I drew up a test target in Adobe Illustrator that divided the area into four sections. I then scaled some elements of the standard chart up and inserted them into three of the quadrants. In the fourth quadrant I placed a color chart. The key here is that two of the quadrants that are most critical can be printed on standard 8.5 x 11 inch printer. Thus I can use a laser printer for the high resolution portion and a inkjet printer with high quality photo paper for the color chart.

In the high resolution area I added a set of diverging lines next to a 6 inch scale. I can use this to judge how well the target printed. On my target the lines become solid at 5/8 of an inch.

This is very much a work in progress. I just got the target finished this week and have not had an opportunity to take any test shots yet.

The files include the test targets(s) in PDF format and the excel spreadsheet. The spreadsheet also gives the horz, vert and diag angle of view for any lens length. Fell free to point out any errors you might find.

Files:

Excel spreadsheet (20 KB)

LBA Full Target (PDF) (984 KB)

LBA Color Target (PDF) (478 KB)

LBA Resolution Target (PDF) (528 KB)