Lens 'Sweet Spot'

It's normally the aperture at which the lens has the best contrast/sharpness. It can vary depending on focal length.

 

I think because of lens variation, it's hard to say with 100% certainty that a lens will be at its best at a specific aperture.

It's mainly just testing with your camera/lens setup to see what is best to your eyes.

 

I would suggest reading posted reviews of your lenses (and those you are considering), most of which give enough information to deduce where the "sweet spot" is. My first recommendation would the reviews posted by Bjørn Rørslett.

Uncle Frank posted last week a link to a compendium of reviews of Nikon lenses.

Most of these will not say in so many words "the sweet spot of this lens is...". In most cases you'll have to read between the lines, but you'll probably learn something in the process. I know I have.

 

"sweet spot" is a vague term to define an aperture-focal length combination that is apparently well-suited to a given type of shot for a specific lens.

It is not exact, nor do most users have any real clue about where their lens produces the "best" results. I think many users have a good general idea what apertures work well for their needs, but that's about it.

For the vast majority of lenses, the so-called "sweet spot" is the range from f/4 to f/11. With fast lenses, this range may widen up to f/2.8 or even f/2 in some cases. Most will be at their peak performance in the range of f/4 to f/11 though.

I wouldn't worry too much. Precision is not really a factor when people talk about this stuff--nor is factual accuracy necessarily.