Focus Issues...

[afliegs]

I'm having focus issues with my new camera (Canon T3i). At the same time that I started shooting with this camera, I also started shooting in the manual modes, mainly P and AV. So I'm not sure if my camera may have front focusing issues (the focus seems to be in front of where I'd like it to be a lot of the time) OR if I just need to get used to controlling more of the aspects of my camera.

Here a couple of examples. These are all shot outdoors with a decent amount of light. It was partially cloudy at about 10am in the morning. I was not using a tripod.

This first one was shot with a Canon 50mm 1.8 in AV, ISO 100, f2.0, camera set shutter speed at 1/1000. I focused on the leaves that my wife was holding. They just don't seem as crisp as they should to me. They just seem a little bit blurry.

http://i197.photobucket.com/albums/aa288/aflieger/Test Shots/IMG_7696.jpg

This next one is even more frustrating because a lot of my pictures ended up looking like this with my wife just slightly out of focus. And this was shot with a better lens and a smaller aperture (which I from the knowledge I do have should make a wider plane of focus). The lens was a Canon 85mm 1.8 and I shot in P with ISO 100, f5.0, shutter speed of 1/400.

http://i197.photobucket.com/albums/aa288/aflieger/Test Shots/IMG_7677.jpg

Please help! It seems like when I shot in Automatic with my old camera, which was not nearly as nice, the focus was always crisp. It might have been hard to get the focus I wanted in complex scenes, but when achieved it looked great. I feel like every picture I take with this camera is just a little off.

I will try to post more examples later tonight when I have time. Thanks in advance for any advice.

 

[mrpink]

Which focus mode are you using?

 

[afliegs]

Which focus mode are you using?

I'm using the AF focus points. I focused on the leaves in the top one and on my wife's face in the bottom one.

 

[afliegs]

Which focus mode are you using?

Auto Focus ONE SHOT, to be more specific.

 

[KmH]

Jeez, the quality of the CoC (bokeh) that lens produces is horrible.

Your problem has more to do with depth-of-field issues and the anti-aliasing (AA) filter in front of the image sensor in your camera.

 

[afliegs]

Jeez, the quality of the CoC (bokeh) that lens produces is horrible.Your problem has more to do with depth-of-field issues and the anti-aliasing (AA) filter in front of the image sensor in your camera.

Which picture do you think has horrible bokeh? They were taken by 2 different lens.What specifically do you think the issues are and what can I do about them?

 

[MLeeK]

Which focus mode are you using?

I'm using the AF focus points. I focused on the leaves in the top one and on my wife's face in the bottom one.

There is your problem. You should be using only ONE focus point and locking that exactly where you want your focus. I fyou are using all of the AF points your camera gets to choose where your focus locks from all of those points. You may think it's on the leaves, but it's wherever the camera picked up the most contrast.
You are also shooting at f/2 which gives you a very shallow DOF to work with, so if it's off just a little bit you are going to see it.

I don't know if it is a photobucket thing or what, but when you are viewing those images make SURE you click on them to enlarge. The focus/sharpness is very different between the image that is displayed than the one that is a little bit larger when you click on it.

 

[MLeeK]

What were you shooting with before you upgraded to the T3i?

 

[afliegs]

Which focus mode are you using?

I'm using the AF focus points. I focused on the leaves in the top one and on my wife's face in the bottom one.

There is your problem. You should be using only ONE focus point and locking that exactly where you want your focus. I fyou are using all of the AF points your camera gets to choose where your focus locks from all of those points. You may think it's on the leaves, but it's wherever the camera picked up the most contrast. You are also shooting at f/2 which gives you a very shallow DOF to work with, so if it's off just a little bit you are going to see it. I don't know if it is a photobucket thing or what, but when you are viewing those images make SURE you click on them to enlarge. The focus/sharpness is very different between the image that is displayed than the one that is a little bit larger when you click on it.

Actually, when I said I used the AF focus points, I meant I choose one of the 7 or so points depending on where I want the focus to be. I don't use all of them at once, just one. And I make sure it blinks red and beeps on the point I choose. But Im not seeming to get great focus. I just uploaded to photobucket to share the picture here, they actually reduce the size automatically. When I zoom in photoshop, I still see the slight out of focus on the larger version.On the picture where the fstop was 5, shouldnt that have been a big enough plane to put my wife in focus? Could it possibly be an issue with my camera?

 

[afliegs]

What were you shooting with before you upgraded to the T3i?

I was using an older version of the Rebel. XT I think. I actually shot a little in manual mode on that camera and never seemed to have this issue.

 

[mrpink]

Jeez, the quality of the CoC (bokeh) that lens produces is horrible.Your problem has more to do with depth-of-field issues and the anti-aliasing (AA) filter in front of the image sensor in your camera.

Which picture do you think has horrible bokeh? They were taken by 2 different lens.What specifically do you think the issues are and what can I do about them?

I suspect that was a sarcastic comment made by Kieth.





p!nK

 

[MLeeK]

In that case...
Have you been using those lenses on the previous camera as well? you have had them for a while? Have they ever been serviced? If you have had the lenses a while they may well be back or front focusing if you know you are locking focus correctly. It's not all that hard to knock a lens out of calibration. It's simple enough to do a focus test to see. Until you can be sure and or have them calibrated (the t3i does not have the micro-adjust feature) you will need to shoot at a stopped down aperture to keep yourself within a safe DOF.
I have mine adjusted at least once a year. I shoot sports so my gear tends to take a few bumps here and there and I do get lenses out of whack. Thankfully I can micro adjust in between calibration.
Just google front or back focus test and you'll find all kinds of advice on testing.

Manual exposure should have no bearing on your focus what-so-ever

 

[afliegs]

In that case...
Have you been using those lenses on the previous camera as well? you have had them for a while? Have they ever been serviced? If you have had the lenses a while they may well be back or front focusing if you know you are locking focus correctly. It's not all that hard to knock a lens out of calibration. It's simple enough to do a focus test to see. Until you can be sure and or have them calibrated (the t3i does not have the micro-adjust feature) you will need to shoot at a stopped down aperture to keep yourself within a safe DOF.
I have mine adjusted at least once a year. I shoot sports so my gear tends to take a few bumps here and there and I do get lenses out of whack. Thankfully I can micro adjust in between calibration.
Just google front or back focus test and you'll find all kinds of advice on testing.

Manual exposure should have no bearing on your focus what-so-ever

Thanks for the good info! I had the 85mm 1.8 with my old camera, but not the 50mm 1.8. The 50mm lens is only about 2 months old. I'll google focus test and see what I can figure out with the 2 lenses.

In the meantime, what would you consider a safe, stopped down aperture? I know if would depend upon conditions, but say the conditions that I shot this morning. Partly cloudy, yet still fairly bright.

One thing I neglected to mention that I just realized - I have a UV filter on the 85mm 1.8 that's been on the lens for awhile (I would consider a fairly inexpensive filter, but never had these focus issues with it on my old camera). Could that be causing some of the issues?

Thanks again!

 

[MLeeK]

First try removing the filter and shooting without it and see what you get. It can be the cause of your problems. Your new camera is a HUGE step up from the XT and the focus system is much more advanced.

Putting a cheap filter on a good piece of glass kind of kills the good glass. I rarely shoot with a filter on my lenses and I definitely remove them when shooting portraits that I want to be crisp.

Yes, it really does depend upon the situation and it also depends upon what you find out on your focus test. Test the lens wide open and then begin stopping down and see what happens. I am guessing that f/5.6 will cover most to all situations. If you are a distance from the subject you may be able to push down as low as 3.5 with no noticeable problems. It just depends on how off the focus is.