Microfocus Adjustment on my 7D

Started Feb 4, 2012 | Discussions thread
Jerry-astro Forum Pro • Posts: 10,017
Automatic adjustment software or EOS Utility

Canon does recommend a distance of around 50x the FL that you're testing. There are lots of opinions here on that, some of which suggest focusing much closer to the MFD for the lens. Most of my own testing (which seems to have worked quite well) followed fairly close to the 50x rule. Also, please make absolutely sure you're using a target exactly perpendicular to the camera, not angled.

There is some software on the market to do this automatically, if you happen to have a PC around somewhere. I'd use it in a heartbeat except for the fact that we're all Mac here.

Here's a link to their site. Reports from people here who've used it are very positive and I've been hoping that someone would do this for ages.


BTW, you might consider simply using a tethered computer along with the EOS utility to do your testing. You can see the image realtime on your screen and use the magnification (either 10x or 20x... can't remember) to see detail. I've found that you can get real close (within ±1 or so) using that method. Best of luck either way.

wallybarthman wrote:

I upgraded to a 7D from my T2i for a number of reasons, frames per second and autofocus being the main reasons but also because of micro focus adjustment.

I have systematically gone through and put every lens I have on a tripod, aimed it at my ISO 12233 chart, taken pictures at a variety of adjustment settings in RAW with neutral picture style, and then looked under a loupe in aperture to figure out which ones was best. Most of my lenses came out in the range of +5-+10 leading me to believe that maybe my 7D was a little off. No problem, that's what micro focus adjustment is for.

This week I went to a swim meet for the first time I had calibrated my 85 f/1.8 and noticed that the swimmer I was trying to take a picture of was out of focus slightly, while the swimmer in the lane behind them was in focus. The 85 f/1.8 was set with a focus adjustment of +10. Then yesterday I took my 120-300 f/2.8 + 1.4x TC out and noticed the same thing - out of focus shots. I set the focus adjustment to 0 and the shots looked a lot better.

So here's my question:

1) What the heck did I do wrong? I tried to be as scientific as I could and so far it seems like I goofed. I will say the distance between the chart and my camera was small (6-8 feet) - would that have had a negative impact on the tests?

2) What's a better procedure?

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