Is my 40D front focusing?

I just did a shoot at a baseball game and all my shots seemed to be slightly front focused. I was borrowing the lens and the owner said that it focused fine on his camera so I thought I would look to the camera as the culprit. I have been suspecting my camera of front focusing before, but thought that it might just be user error or due to the fact that I was shooting with the 28-135, which can be soft on the long end. I did this test and it seems to me that something is off. (This was done with my 40D, 50mm f/1.8 @f/1.8, autofocus, sat on table top with timer.

1. On this one, I was focused on the second A, second battery from the right.

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Not sure about the focus plane, to me it looks like the angle is too straight to actually judge this. Download a focus test chart instead, set the camera on a tripod and make sure there's no risk for camera shake, etc.

I don't recommend the widely-used focus chart that you're supposed to shoot at 45 degree tilt. Lots of people (including me) have gotten false alarms from it, mostly because they're shooting at very close range to fill the screen with the chart.

Your battery test is a better way to go, but you should space them out side-to-side more so you know for sure which one the autofocus is looking at.

Bear in mind that the actual autofocus area is at least twice as big as the spots in your viewfinder - and that, if two objects are in the area, the AF will select the nearest one.

Also you should be aware that Canon's specification for testing focus is a distance of 50 X focal length, so at 50 mm that'd be 2.5 meters or a bit over 8 feet.

-js

number six wrote in post #7510620
I don't recommend the widely-used focus chart that you're supposed to shoot at 45 degree tilt. Lots of people (including me) have gotten false alarms from it, mostly because they're shooting at very close range to fill the screen with the chart.

Your battery test is a better way to go, but you should space them out side-to-side more so you know for sure which one the autofocus is looking at.

Bear in mind that the actual autofocus area is at least twice as big as the spots in your viewfinder - and that, if two objects are in the area, the AF will select the nearest one.

Also you should be aware that Canon's specification for testing focus is a distance of 50 X focal length, so at 50 mm that'd be 2.5 meters or a bit over 8 feet.

-js

Thanks for the info!

Here is how i run the batter test. Make sure there is enough space between batteries so that the focus point does not get confused. Also, get better lighting.
https://photography-on-the.net …php?p=5809926&p​ostcount=7

Found this post as well. A much better focus test setup.
https://photography-on-the.net …hp?p=5885029&po​stcount=22

Wow, they're not taking any chances on target error, are they?

Looks like they specify 1.5 meters distance for a 50 mm lens and 3 meters for a 100 mm.

I suspect it doesn't matter if it's 1.5 or 2.5 meters, just so the distance isn't around .5 meter like you usually see for the focus chart.

-js

gjl711 wrote in post #7510741
Found this post as well. A much better focus test setup.
https://photography-on-the.net …hp?p=5885029&po​stcount=22

The pictures look good but I don't understand the lingo!