a question about focus

No offense meant at all here, but, I have to point out the contradictions:

How will this get the face and eyes in focus?

Shooting ambient light portraits in low light at F8 eh, hows that working out for ya?

No offense taken. Most people have their heads right on top of their chests, so that both are in the same plane of focus. If one is in focus, everything in that plane is in focus. It's a simple trick to use for autofocusing. I mentioned f8 because according to the exif info, the photo was shot with flash not just ambient light. I hope that clarifies the apparent contadictions.
Personally, I never take indoor pictures with ambient light because the colors are awful and you need a tripod. I never got into studio lighting, so I stick with a flash. It's fast, reliable and spontaneous. It's personal preference and it works for me. It might work for others too.

it's probably the sigma lens

I have a similar problem with my sigma 18-50

Try half pressing the shutter twice before taking the shot, this seems to improve the success rate.

Also in some circumstances you can just about see in the viewfinder by half pressing if the image is sharp.

It's a frustrating problem, the lens seem capable of getting a sharp lock almost every time but only after two presses. Maybe they are all badly adjusted because if it focused on the first half press like it does on the second nearly all the shots would be in focus.

I described the problem and my way of getting around it here.

https://photography-on-the.net …hread.php?t=187​402&page=2

Oh I have my share of issues with my Sigma, however these were shot with the Canon.

René Damkot wrote:
A few problems with this;
- prefocussing on a shirt will give you a sharp shirt, not a sharp face. If you are luck that is, 'cause focus-recompose isn't the best technique.
- When in low light, using f/8 kinda defeats the purpose of a fast lens....

@ Skrim17: did you focus between the landscape and portrait shot? If not, that's the problem. And yes, the 50/1.8 can be inaccurate.

i just came from a workshop and some of my pictures were super out of focus, and i was wondering why the hell that was when i focus locked and recomposed. you just answered that big question i had in mind. But now, the question is, are we locked to using the different AF sensors then? darn!

thanks!