"Sweet Spot" for lens...

[kay1547]

not every lens is the same but typically f8 will give a very sharp images, but if you don't pixel peep then it could be hard to tell f4 all the way to f9. Bokeh is nice but some shots simple don't need a shallow depth of field to make a great shot, so if you don't have to don't always shoot f2.8
If you really want to know what works best on your lens you will have to shoot the same object through all the fstop then look at it 1:1, my guess is you'll be happy with anything from f4+
when you do this test i recommend taking 3 shots at the same fstop, if you have cheap glass you may find then sometimes it will miss autofocus.
for example the 50 f1.8, sometimes i'll get razor sharp f2 images and sometimes they come out a little soft. the lens is cheap and so is the gears focusing so its hit and miss.

 

[StandingBear1983]

Well if you buy a 1.8 or 1.4 lens and you don't shoot wide open...whats the point?, in most cases its user error that causes the pictures to blur or not be sharp...very rarely its the lens...if you have the d800 its supposed to lock focus very well, make sure you got down all the technical stuff, holding the camera steady, using exactly the focus point or focus and recompose without moving forward or backwards...even breathing and your hand on the shutter...do all these things before blaming the lens.

 

[grafxman]

What is your bench-test method. wanting to test my primes before upcoming photo shoot.

I've tried a few different methods. There are some images you can download and print out. There's also someplace on the net where you can call up an image on your computer screen. None of those methods worked for me because they all use some weird, bizarre pattern that gives me a headache if I look at it for more than five minutes. I can't tell anything about lens sharpness from those unfamiliar patterns because my brain can't make any sense out of them.

After I thought about things for a while I realized I had to use something that made sense to me. This means I had use a pattern that was readily available that I was familiar with. So I took a sheet of the newspaper, taped it up to the patio door then set up my tripod on the patio. Any text that is not tack sharp is instantly recognizable because I've been looking at text all my life. It's cheap and easy to do. Just make sure you get your camera exactly perpendicular to the wall, door, window etc. or else your results will be unreliable.