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I have a Canon Rebel T1i with the default Canon lens.

When I shoot with it, I use Auto Focus and get the red dot indicators in the viewfinder as expected.

But even though it looks like the camera is auto focusing correctly the pictures look blurry where the red dot indicated. Other areas of the photo are in focus (areas that I don't want to be).

It's as if the camera is focusing in the wrong place.

Any idea what could be the cause?

the autofocus point was in the center of green and white hosta plant in the middle of the photo

edit: here are some more samples, in all of these the autofocus point was on the center line

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mjr
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  • possible duplicate of What causes blurred/non-sharp images taken of stable objects? – Itai May 15 '13 at 19:03
  • Thanks. I should clarify, that parts of the image are in focus, but the area where the red dot indicates is not. It's as if the camera is focusing in the wrong place. I'll update the question. – mjr May 15 '13 at 19:15
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    Assuming the area under the red dot is not moving, you may have the camera suffering from front or back focusing issues which are also already covered on this site. Without a sample image or a few, it is hard to tell what is happening. – Itai May 15 '13 at 19:21
  • That example is a bit hard to tell anything from. What were you focusing on? What are the camera settings? – mattdm May 16 '13 at 13:39
  • The camera was focusing on the center of the green and white hosta plant in the middle of the photo. I was shooting in AV mode, ISO 100, shutter 1/60, aperture 5.0 – mjr May 16 '13 at 14:09
  • Try my suggestion, I added it to my comment. – Itay Gal May 16 '13 at 21:10
  • Be aware that the AF sensor is often much larger than the red indicator dot. It may not be an actual problem -- the camera could just be locking on to something other than what you expect. – mattdm May 16 '13 at 21:19
  • I think you may be performing the tests wrong. AF tests MUST be performed with precision...at proper distance, with the test chart at EXACTLY the correct angle, with the test chart properly level in the frame, etc. It is also really best if you brightly illuminate the test chart, as AF performs slower and less accurately in lower light (a point NOT made frequently enough). The first thing I see is that the test chart, distance, and illumination are all off. The chart is not properly angled to the lens...it should be entirely parallel to the sensor, and properly horizontal. – jrista May 21 '13 at 18:33
  • It should also be noted that lenses and cameras can be non-ideally calibrated relative to each other. The Rebel line of Canon cameras does not offer AF micro adjustment (AFMA). The only way to fix front or back focusing, which CAN and DOES occur, is to swap out for a different lens. – jrista May 21 '13 at 18:35
  • I've had the camera for a few years, and I'm sure it's been jostled around some in that time. I'll find a local repair shop to take a look at it. Thanks for all the help. – mjr May 21 '13 at 19:08
  • @mjr: Generally speaking, Canon requires lens/camera alignment and lens repair to be done by an actual Canon Factory Service Center. If you take it into a local repair shop, they will most likely send it into Canon anyway, however that usually takes longer. Canon puts direct customer requests at highest priority, and turnaround time is usually no longer than a couple weeks (could be as long as 4-6 weeks with a local shop.) Also keep in mind, the service is not free, nor is it particularly cheap...I recently spent $500 having JUST a lens repaired for a minor thing. – jrista May 21 '13 at 19:31
  • Thanks for the tip. I called canon and will be sending it out. – mjr May 22 '13 at 13:49

2 Answers2

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Some lenses have a calibration problem, aka, front focus or back focus. You can easily test your lens and find out if that is the problem.

There are some great guides on the web, you may want to google it: "front focus lens test"

Edit: Try to print this photo and shoot it from a low angle while focusing on the line in the middle. Use an open aperture. Then upload the it. Basically you'll see if the focus was on the line or not. if not, you have a calibration problem.

Focus Test

Itay Gal
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  • You probably want a larger, much higher resolution version of that image as well. Printing that tiny thing out is going to result in a soft chart right off the bat, making it difficult to precisely tell where your focal plane is. You want a version of that chart that can be printed on an 8.5x11" with at least 300ppi resolution (600ppi would be better). – jrista May 21 '13 at 18:36
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It appears your camera and lens combination is suffering from back-focus.

Given you have an entry-level camera, there is no way for the user to correct this. You must send your camera and lens to a Canon authorized service center for calibration. If you have other lenses, they can calibrate multiple in one batch.

Itai
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