Focus Calibration Chart. Download the focus chart. This focus calibration chart can help you test the accuracy of your SLR camera's autofocus, and find the right focus micro-adjust setting if your camera has that feature. It's designed to be printed out and stuck onto poster-board, to make an accurate free-standing focus target. Testing procedure. Prepare the test chart: There are many ways to prepare a test chart. Here are two of them: Create a test chart using Quick MTF or download a printable version of the ISO 12233 chart, then print it out using a high quality printer.Buy a test chart.
The first chart type (shown above) provides the 'Average' results for a lens and the second shows the 'Variance' within a lens model. About the MTF Average Testing With grossly decentered or tilted lenses removed from contention, 10 lenses of each model are selected for testing (at wide open aperture). Analyzing Lens Testing Chart Images. The images you shoot can be analyzed for sharpness and chromatic aberration quite easily. The numbers on the lens testing chart represent the line pairs per mm (lp/mm) values of the test patterns they are next to.
The ISO standard for measuring resolution of “electronicstill imaging”' cameras is 12233, available only from theInternational Standards Organization for only 116 Swiss Francs(about $US93 as of this writing) and under copyright protection. Butthe design of the test chart seems not to be protected; itsdescription has been available on the Web in an Excel spreadsheet. Ihave semi-manually converted this to an Adobe Illustrator file whichis displayed here.
The display to the left is an SVG document. If you see text instead of the chart, you probably are using Internet Explorer or an outdated version of another browser. Either update or wait for Internet Explorer 9, which is expected to support SVG. If something shows up, but seems to be missing something, it's possible your browser has bugs in rendering SVG. |
Click here for a printable PDFversion. The size is 15.75×8.45 inches (400×240mm); youwill probably have to resize to fit your printer.
In principle, you should be able to print this chart and performresolution tests on your camera. The reality isn't that simple; thereare lots of subtleties having to do with focus distance, quality andcontrast of your printer, evenness of illumination, surfacereflections, etc.
Advanced resolution tests
It seems that most folks, for example ImagingResource, use this chart for visual assessment of resolution, butit's designed to do more. See those funny crooked “H”' shapes andsquares? These provide data for computational analysis ofresolution; tools are available at this site to performthis analysis; for more information, see thispage.There is at least one companyselling a low-cost (<$US100) kit for measuring resolution by meansof this slanted-edge technique.For more info, I suggest a Googlesearch or the Wikipedia article on optical resolution.
![Lens Lens](/uploads/1/2/4/6/124636187/159464422.jpg)
Buying a real ISO 12233 chart
The proper way to perform these tests is to order both the ISOstandard and a properly-made test chart. The latter are available,for example, from PrecisionOptical Imaging in Rochester, New York. See the I3A site forworldwide sources. Expect to pay more than $US100 for such a chart.The alternative is to do it on the cheap: take the PDF file, print itin an appropriate size, download the code, and start testing. I thinksome people have posted raster images (e.g. JPEG files) of the charton the Web; the outline description here should produce a better testchart, as it isn't limited to pixel-level resolution.Camera Lens Test Chart
DISCLAIMER
I have tried to reproduce the ISO standard test chart using theofficial ISO data, but neither I nor Cornell University guaranteescompliance with ISO 12233 or any other standard, nor do we take anyresponsibility for the quality of results based on this chart.
![Download Download](/uploads/1/2/4/6/124636187/475379509.jpg)
Patients
Camera Lens Test Chart
Searching for a free eye chart to check your vision at home?
Simply click on the image to the right, and your download will begin. You can use this eye chart to check your entire family's vision.
Remember: This is not a substitute for a complete medical eye exam by a licensed optometrist. But it could help you identify potential vision problems that demand professional attention.
Need the JPEG version? Click here.
How to Use the Eye Chart
- Print the free eye chart on regular 8 1/2 x 11-inch paper
- Tack or tape the chart to a windowless wall in a well-lit room at eye level
- Measure ten feet from the wall
- Cover one eye (if you wear glasses for distance vision, keep them on)
- Have another person point to each line as you read the letters out loud and keep track of which letters you get right
- Continue to the bottom row or until you can no longer read the letters
- Write down the number of the smallest line where you identified the majority of letters correctly (Ex. If you were able to read 5 out of 8 letters on line 8, you would write 20/20.)
- Cover the other eye and repeat steps 5-7
What Do the Results Mean?
That depends on the age of the person being tested. A 3- to 4-year-old should be able to read the 20/40 line, and a 5-year-old the 20/30 line. Older children and adults should be able to read the majority of letters on the 20/20 line.
If you notice any results that fall outside these standards, be sure to schedule an eye exam with your Vision Source doctor.
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