What F stop to get ultra sharp images?

Still pretty new to photography. Had a 30D, then was forced to sell it when I lost my job. Recently got back into the DSLR world last couple weeks with some new equipment. I think I have always been caught up in the bokeh and blurry background and find myself ALWAYS on 2.8 or 1.8 (only have 2 lenses)... i rarely, ever move it up from whatever is wide open.

But... now that im starting to play in lightroom, im noticing that they arent very sharp and im a bit disappointed.

so that got me to thinking, its probably the fstop, because i already try and keep ISO down as much as possible. So my question is this... GENERALLY speaking.... and say you have plenty of light..

1. what F stop do you use if you arent worried about bokeh and just want a SHARP image
2. whats secret if you do want bokeh and still want face or object in front to be SHARP?

also, i almost always use center focus point only... is that hurting me as well?

every lens is different, but typically, most lenses are sharper when stopped down a bit from wide-open... there's no magical number saying "the lens will be sharpest at f/8" ... play around with your lenses, and figure out the sharp spot... find a static subject.... put the camera on a tripod... and shoot away.

Mostly dependent on lens but in general on my primes 2 "clicks" (as in 2/3 of a stop) and I'm good (if I still want to retain some degree of bokeh). Most people will say 2 full stops for very sharp images. If all else fails go f8.

I use the "outer" points on the 5DII regularly but I don't quite trust the outermost two laterals. YMMV.

do you have an iphone or ipod touch?

if so, check out the itunes store for Simple DoF Calculator.
http://itunes.apple.co​m …lculator/id3012​22730?mt=8

this will show you, according to your focal length and aperture, what area of your shot will be in focus, and what will start to blur out. I loved this program, until my ipod touch took a bath

as va_rider mentioned, there isn't a single "sweet spot", but every lens is typically sharper when stopped down a bit.

2-3 stops down from wide open has been the axiom for years. Look at the MTF charts at photozone.de for your lens for the real answer.

f/8 with no higher than f/16 on a cropped. Every lens is different, my suggestion is to look for sweet spot of lens on photozone.de

I have 5D Mark II and 24-70L is mainly combo Im speaking about. I also have 50mm 1.8 but dont use it as much.

I find it will be f5.6 to f8, depending on the lens. I avoid going past f11 unless absolutely necessary for the photo. Two to three stops down from max aperture is a reasonable recommendation, but some lenses are at their best wide open, and some improve to maximum sharpness with one stop down from max aperture. Some of the ultra fast lenses are designed to be used wide open. I don't have one, but I have read that if you want to shoot with the 50L, it may do best at closer distances when wide open.
For some photos, I don't want maximum sharpness, and prefer a wider aperture.

Couple of stops down from wide open is usually a good starting place for best sharpness. I used to have my lens set at f8 or f11 as a 'walkabout' setting back in film days....

On my 2.8 lenses, i'll go from 5.6 up to about 8

Let's see some examples to see what is going on. Maybe it is not an issue of running a lens wide open, perhaps it is one of the other settings utilized during the shot. Could you please post a sample of what you are seeing?

OpticalPrime wrote in post #11917539
I have 5D Mark II and 24-70L is mainly combo Im speaking about. I also have 50mm 1.8 but dont use it as much.

The 24-70 will be at its sharpest at f/5.6 to f/8, but it should still be very sharp close to wide open.

I generally don't pick apertures based on sharpness, I just pick the aperture I need for the depth of field I want.

I don't generally buy a f2.8 lens to shoot at f8... thats just crazy. I would pick aperture based off of light needed or DOF desired, not sharpness.

I do own some lenses that are sharpest wide open. The general rule is a general rule.

The worst f/stop is one stop down from wide open, for many lenses. Most lenses are optimized for wide-open resolution, but f/8 is generally the best compromise between sharpness, DOF and diffraction.

If you shoot wide open, be aware that your autofocus system has inherent errors that are most evident wide open. Shooting f/8 overcomes those errors, something not to be ignored.