What is the sharpest f-stop number?
What is the sharpest f-stop number? Let it be clear that in this post I’m not talking about DOF, but the sharpest f-stop number of lenses optics.
There is no defined “sharpest” f-stop number. But each lens has its own sweet spot. There is no way to calculate your way to find the sweet spot, it’s found by trial and error. I will show you where to find the sweet spot on your lens! So, you can take your super sharp images, and get an amazing result on your photos every time!
To find the sweet spot you must take lots of pictures of a “photograph test target”. This is a long a time-consuming job, and can be big task to take on. You can also get inconsistent results when doing it yourself, just bumping lightly in the tripod can change the results significantly. But isn’t it great that there’s a whole site dedicated to find the sweet spot! A site that does all this for you! Dxomark is the leading go to site when looking at lens sharpness. They tell you the exact sweet spot for your lens and camera combo. It also tells you how many megapixels you will get with your lens and camera combo. Also note that the camera can have a major effect on how sharp the lens is, and the sweet spot of the lens. Currently (04.11.2017) the best lens on Dxomark is the Sigma 85mm F1.4 DG HSM A Nikon on a Nikon d800E. But using this lens on my main camera house, the d5300 is not near as good as the d800E. The score on the Sigma lens with the d800E is 51, which is excellent on their rating scale. But changing back to the d5300 the score rapidly goes down to a score of 33 which is just a mediocre lens rating. The difference from different camera houses and lenses are huge, and the sweet spot varies just as much as the megapixel count.
Remember that the sweet spot isn’t the sharpest of all the f stop numbers on your lens. The numbers above it are mostly the same sharpness. The sweet spot is the lowest f-stop that gives you the sharpest results. Some lenses are also quite soft on the edges of the image. The sweet spot might be a lot higher because of that. In some cases, the sweet spot can be on f/16 while its tad sharp in the middle on f/8 and soft on the edges.
To be completely sure what the best f-stop is on your lens you should visit Dxomark. Also, you can find out the megapixel count, color fringing, contrast charts and a lot of other technical specs. If your lens and camera combo isn’t on the site because it’s newer lens, you can assume that it’s probably sharpest on full open aperture. Why? Because most lenses manufactured now focus on getting the sharpest result on full opening. I shoot most of my shoots on f/5.6-8, because I find these f-stops the sharpest. This is something that you can “feel” your way towards. When shooting, and you are not sure what’s the sweet spot, assume it’s f/8.
So how DO you find your sweet spot. You can either do it yourself with a photograph test target, or you can go to Dxomark and search for your lens and camera combo. If you can’t find or don’t bother to find out, shoot on f/8.
https://www.dxomark.com/ https://photography.tutsplus.com/tutorials/how-to-calculate-the-sharpest-aperture-for-any-lens--cms-25153 https://www.bhphotovideo.com/explora/photography/tips-and-solutions/how-test-your-lens https://photographylife.com/how-to-choose-the-sharpest-aperture https://en.wikipedia.org/wiki/F-number