RRS Loc: Not sure

Karl, several things. In your first shot the scene is very busy, spot focus would or could have helped. By looking at the rest of your shots it appears that you are back focusing, not by much but by letting the aperture and ISO float you really have very little or no control over DOF. Shoot in manual, set shutter speed and aperture and let the ISO float. Pat attention to the ISO as you compose in the view finder and if if is higher then what you want adjust either the shutter speed or aperture to bring the ISO in line. Since the bird was sitting you may have been able to lower the shutter speed or use a smaller aperture would have been my choice. Check your focus alignment and focus with single spot. You are close and these shots with very little PP and printed small really don't look all that bad. I'm glad that you are seeing that you want better and sharper images, stick with it. I have a feeling that you won't stop until you are satisfied and that's great!

imagemeister Loc: mid east Florida

If you let off the BBF, it is conceivable that the bird moved - losing your original focus point - OR, the movement of the bird caused motion blur ........Lastly, judicious PP'ing can and WILL help this image !

Bill Emmett Loc: Bow, New Hampshire

I took a close look at the bird in all of your shots. If you would zoom in as close as possible in your PP program, you'll notice the shrubbery, grass and sticks in front of the bird is slightly more in focus than the bird. It appears the lens is focusing slightly "front focusing". This will cause the image subject to appear "soft". This is most evident in the first image, where the evergreen leaves are in focus right in front of the bird, and the bird itself is soft. In the image with the bird on the ground, the grass in front of the bird is in focus. I hope this helps.

B

jeep_daddy Loc: Prescott AZ

One thing I noticed is that your shutter speed is only 1/640. That is not fast enough to be hand holding a 100-400 lens at 400mm. I suggest you use Aperture priority and bring the ISO up until your shutter speed is at least double that or 1/1200th. I always try to keep it higher than that unless the light is so poor that I can't. Also, I don't know how steady you are at hand holding, but if you are like me, getting up in age, you might benefit from a tripod or monopod.

Photocraig

Thanks for the link. I like this source and the article and examples are clear and excellent. I learned about BBF from this site and used the Canon support note to get it working for my old 50D. What works so well for me is that it harmonizes with how I learned to operate cameras in the Manual days (DAZE?). Exposure, focus and shutter actuation were separate operations. With auto exposure and aperture or shutter priority they do blend in the the 1/2 shutter stroke. But with single point focus I can pick the focus point and choose when and where I want to focus. They are inherently separate mechanical and creative functions. I'm glad to have the option to keep them that way.

The Servo invention is pure magic and has been a mainstay for EOS shooters for decades. And they all can come together very easily on even the oldest most entry level Canon bodies. And, I'm sure t'others do it well too. If it is available, use it. It will put the photographer in more control and result in more keepers.

kbatschke Loc: Chicagoland-west

Thanks for your thoughts. I was supporting the camera firmly against a tree or post (depending on my location at the time) but may still have had movement of course. Camera was set at TV to lock in the shutter speed but I'll try higher SS. The subject was going in and out of shade so I was concerned about higher SS and corresponding high ISO. I set my camera to a max 3,200 ISO to keep noise at a usable level.

imagemeister Loc: mid east Florida

Do not discount blurring from SUBJECT movement !

jeep_daddy Loc: Prescott AZ

That's why I suggested a faster shutter speed.

twoods

Curious on the common AI Servo suggestion. I too shoot a Canon 70D, currently with a Tamron G2 150-600. In AI Servo mode, my images are fairly soft. In One Shot mode, they start to gain better focus. I tried it again yesterday just to check it after reading this post and AI Servo just will not give me a solid focus. It's pretty frustrating when you get a shot and can't make it happen. I am using BBF and have a solid rest to support my lens.

CHG_CANON Loc: the Windy City

Did you follow the link provided as well as the comments to keep the AI Servo AF active through the shooting? A few ideas: the Tamrom lens cannot keep up with the AF motor? You're not holding the BBF keeping the focus active while shooting? The consensus is this is the method for shooting action. We'd have to look into your equipment and / or technique if single shot AF seems to be working better for action where AI Servo is the desired setting.

Dun1 Loc: Atlanta, GA

Try A1 Servo, Single or Spot focus especially to capture shots.