Is my 20D front focusing?

Looking for opinions, I'm 99% sure my 20D is front focusing. I've tried a number of tests with similar results. The attached photo was with the 100mm macro at f/2.8 in daylight. The full sized image on this and other photos clearly show the top of the 'F' in the word focus being OOF. Is my 20D front focusing?

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Something's front focusing a little. Focusing is controlled by the lens, cameras can be tweaked a little I think. Try another lens and see what it does.

I suppose it's worth noting then, I had similar results with different lenses.

That doesn't actually look too bad to me. When my XT was front-focusing, the FOCUS-HERE line was completely blurred out and unreadable. If you consider the very, very narrow DOF involved here, that the lens might be focusing on the very front edge of the FOCUS-HERE line and that the chart appears to be slightly off-centered, it looks pretty good to me.

If you're still unsure, try shooting some text, book spines, newspaper, etc. at roughly 20 feet and see what results you get. If that's in focus, I don't think you have much to worry about.

It doesn't look terrible, but noticeable. If you see similar results with your other lenses it's definitely the camera. If you send in the camera with a few test shots done with different lenses showing the same amount of front-focus, and tell them to adjust the focus just slightly to the back, they should be able to do that for you. It's a good idea to get the camera properly calibrated, because if you ever get a new lens that is also slightly front-focusing, the aggregate front-focus of the body + lens will cause the final focus to be more significantly out of focus.

I've tried two different lenses so far with differing results.

100mm Macro at f/2.8 as pictured.
24-105 @105mm f/4 - With that lens it looked as though it was focusing at around 6mm.

Admittedly the tests I tried were a little haphazard/rushed at the time, so they could be slightly off. I guess I need to try out a few additional tests to be certain.

where do you get the chart for this test?

I think tis is about right for a 20D, I had mind pro checked at an expo' last year and it too had a front bias, but I was told this was the norm for a 20D.

VladDracule wrote in post #4004741
where do you get the chart for this test?

If you do a google search for focusing chart, it will be the first link.

hoogerhs wrote in post #4004303
I've tried two different lenses so far with differing results.

100mm Macro at f/2.8 as pictured.
24-105 @105mm f/4 - With that lens it looked as though it was focusing at around 6mm.

It might be the 24-105 lens then. Do you have something like the 50mm f1.8 you can also test? Also try a few longer distance tests.

Well, worse case scenerio is that you send in the camera and the 24-105 and let Canon sort it out. From experience, they seem to do a better job with a front-focusing issue when they get camera and lens anyway.

tim wrote in post #4000921
Focusing is controlled by the lens, cameras can be tweaked a little I think. ...

Front/back focusing I believe is a difference between the light path to the sensor and the focus screen. If the light path is of different lengths then the image will not be what you see in the viewfinder.

VladDracule wrote in post #4004741
where do you get the chart for this test?

http://focustestchart.​com/chart.html

gjl711 wrote in post #4005304
Front/back focusing I believe is a difference between the light path to the sensor and the focus screen. If the light path is of different lengths then the image will not be what you see in the viewfinder.

I assumed we were talking about auto-focus. An incorrect viewfinder offset would only affect manual focusing.

In my case, it is autofocus.

Considering my 20D and lenses are long since out of warranty... anyone have ballpark figures for what canon charges for this kind of service?

Thanks
-Steve

JackProton wrote in post #4005239
It might be the 24-105 lens then. Do you have something like the 50mm f1.8 you can also test? Also try a few longer distance tests.

Well, worse case scenerio is that you send in the camera and the 24-105 and let Canon sort it out. From experience, they seem to do a better job with a front-focusing issue when they get camera and lens anyway.

I do have access to a 50mm f1.8 I can try, I also have access to a Rebel XT (300D) which could help me narrow it down to a lenses versus body.
Looks like I will have to perform a few different tests here to narrow down whether I actually have a problem or not and whether or not it is my lens or camera body (or both).

Thanks for all the feedback so far.

JackProton wrote in post #4005364
I assumed we were talking about auto-focus. An incorrect viewfinder offset would only affect manual focusing.

Sorry, I didn't mean to say viewfinder. The light falling on the sensor does not take the same path as the light you falling on the focus sensor. The focus sensor gets it’s light bounced off of the secondary mirror, the image sensor get the full, un-bounced light from the lens. If the mirror and sensor are a little out of alignment and one path is longer or shorter, then the camera will think it is in focus when in reality it is not. Page 21 of the 40D white paper has a nice cut away and you can see the various light paths.