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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.

The principle is simple: you set up your camera level and square-on to the focus chart, take a picture, and then use the distance scale to assess how far in front or behind the target your camera actually focused. For reliable results it's best to take several photos, manually resetting the focus to infinity between each one. The recommended distance between the camera and the focus chart is around 50 times the focal length of the lens.

Footnote: the version in the PDF is slightly improved from the one shown above. I've increased the number of contrast lines in the centre of the target based on some info I read from Canon.

Other focus charts

Tim Jackson's focus test chart is a model of simplicity. You just print it out on a single piece of paper, lay it on a table and photograph it from a 45° angle.
Unfortunately the original URL for it, http://focustestchart.com/chart.html, no longer works, but if you may still be able to find a copy via Google.

Here's an excellent article by Keith Cooper that covers AF microadjustment in considerable detail, including a clever method of focus checking developed by Bart van der Wolf, using Moiré patterns on an LCD screen:
www.northlight-images.co.uk/article_pages/cameras/1ds3_af_micoadjustment.html

Invisicord.com provides a chart that is similar in principle to mine, but it's designed for simple assembly by just cutting and folding, no need to stick it to poster-board:
photography-on-the.net/forum/showthread.php?t=750736
www.invisicord.com/docs/invisicordfocuschart.pdf

There are a couple of commercial products that also work on a similar basis to mine: the SpyderLensCal from Datacolor, and the LensAlign Mk II from Michael Tapes Design.


A note about linking

If you want to link to my focus chart, please link to this page; don't "hot-link" directly to the PDF file.

The bandwidth to host these files is not free. I've started hosting the Google ads you see on these pages to defray a small fraction of my hosting costs. If you link straight to the PDF file, then your readers will be downloading the PDF from my site without seeing my ads. If they don't see them, then they can't click on them; and if no-one clicks on them then I'm out of pocket (or rather, even more out of pocket than I already was). Thank you for your co-operation.

I am now using protection against hot-linking on the PDF files. If you're reading this then you shouldn't have any problems with the links, but if you are having problems downloading the PDF forms, then please contact me via the contact form.