70-200 f4 sweet spot ?

Has anyone figured out the 70-200 f4's sweet spot, aperature wise. I never go past f9, I have shot at f4, but rarely inbetween. I am refering mainly to people images.
I know the lens is sharp wide open, but has anyone noticed a sweet spot?

I find F4 to be the sweet spot, check out this portrait I did of a friend of mine. F4 @ 200mm

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That's Great..
I love the DOF at f4 on this lens. I also love the Colors, and contrast right out of the box.
You know this is the one lense out of my line up, that when I shoot with it, I end up doing very little photoshop work afterwards.

Anyhow, I just wanted to confirm my curiousness. I did some portraits of my next door neighbors child with the lens a few weeks ago, (I still haven't edited the images), and on the LCD they look razor sharp.

I was just curious if other people shot at anything other than f4.
I shoot manual 90% of the time, so I am always changing settings.

Shot mostly at f8 to f16 (ISO 100) handheld while in Egypt. Then again, it was always very sunny.

Will shoot at f32 for telephoto landscapes or detail shots while mounted on a tripod to maximise DOF.

f32....??
Can I see a sample image at that f-stop.
I saw a shot at f-16, and I didn't really like it to much.. then again you said you used a tripod, so that is a difference.

Tripod is essential to shoot at f32 unless you bump up the ISO to 3200 resulting in poor quality.

Will try and post a shot tonight from home taken at f32 on a tripod.

Don't have the lens (yet) but most lenses are said to be sharpest about 2-1/2 stops down from the max aperature.

No matter what aperture it's set at, it's sharper then what I'm used to!! I can't complain about it through the spectrum.
Bruce is right, I was amazed when I applied my 'standard' curve adjustment and actually made the image look worse.

I'd say the sweet spot is right at the end of my camera.

f5.6!!!

Ro1

I find f8 works fairly well when you are outdoors in good sunlight