Is my Sigma 70-200 messed up? (RAW image link)

[caseysrt]

I took this shot today to just test it out and it has always been like this. To me it's not sharp at all. Is this just the nature of the lens or is there something not right with it? I got it used from eBay if that means anything.

Here is the image out of camera with no adjustments, the RAW file is below it.




http://caseysexton.com/DSC5131.nef

 

[caseysrt]

Settings were 1/400 f2.8 ISO 200 @ 200mm

It's like this no matter the settings though.

 

[katerolla]

Just had a look at your image at 100% crop, the focus is fine, you have focused on the dead centre (the text on his shirt and his right fingers) you have to remember that 2.8 is an extreme shallow depth of field, you must get in right with in a millimetre, not sure what camera your using but if you can change your focus point to focus on his eyes, this will take a little practise.

 

[Espike]

I agree with katerolla. His face is OOF but the part of his shirt that his fingers are next to is very sharp. Were you using single point focus aimed right at his left eye? Also like katerolla mentioned, 2.8 is a very shallow DOF. Try something like f/8.

 

[caseysrt]

Wow, I think you're right. I cannot believe that I've been missing my focus this while time. I knew that 2.8 was a very shallow DOF, pair that with a full 200mm zoom without a tripod and I'm guessing this will happen every time.

My main problem is because of my vision problem I cannot see the focus point light up. You think it would be okay to substatute the focus point with the light up square in live view mode when using this lens?

Using a D3100 btw.

 

[Espike]

I've got zero experience with Nikons, but on my camera I've found the AF in live view to be extremely inaccurate. I wear contact lenses like 95% of the time, but when I wear glasses, I have to take them off to look through the view finder. Because my vision is also pretty bad (maybe not to your level, but still...) I listen for the AF beep. I've found that works for me.