Auto focus doesn't work on bird surrounded by foliage

[rfermat]

I have a Canon EOS 5D Mark III, purchased in late 2016.  I've taken at least 10000 photos with it.  I use either the EF 100-400 IS II or the 70-300 image stabilizer lens.  In either case, when I am photographing a bird that is perched on a branch and has background foliage, AF usually doesn't work.  I have lost at least 70% of the oppotunities for such photos, as eventually the bird flies off.  The %$^&#$ camera insists on focusing on the background or foreground.   These are situations where I am reasonably close to the bird, so that it opccupies maybe 1/12 or 1/16th of the image.

This is beyond frustrating.  I have experimented with many different AF settings and nothing seems to do any good.  

Anyone else have this problem?

[Waddizzle]

---

@huskyC wrote:

Nice shots. What are the gears you used and settings please ?

---

Brewers Blackbird

EOS 6D Mark II, EF 100-400mm f/4.5-5.6L IS II USM+EF 1.4x III

@1/1600, f/8, ISO 2500, @560mm

[EDIT]]

It is the same photo, BTW.  These are cropped and uncropped versions of the same photo.

[rfermat]

Nice shots.  I almost never use ISO above 500.  Maybe I should.

BTW that's a Common Grackle.

[Waddizzle]

---

@rfermat wrote:

Nice shots.  I almost never use ISO above 500.  Maybe I should.

BTW that's a Common Grackle.

---

I am no bird expert.  I looked it up, and came up with what I thought was a good match.

With a 5D3, you should get great results at the higher ISO values, too.  While many prefer to shoot Av mode, I prefer to use Manual mode with ISO set to AUTO.  I set an upper ISO limit in the menus.  I want a fixed shutter speed and aperture setting.

[ebiggs1]

"I almost never use ISO above 500.  Maybe I should."

Yeah, you need to rethink that. 800 to 1600 is great and sometimes I use 3200.  Remember each doubling of ISO is one stop.

The question becomes is one stop going to make the photo?