Not every f-stop on your lens churns out equally sharp and well-defined images. At least, that’s what I learned from John Sevigny’s article. Highlights below:
“A photograph shot at 1.7 relies on nearly all the glass in the lens, and any surface or engineering imperfections are going to be revealed with a wide-opened aperture. For the same reasons, I can probably forget about the idea of shooting at 2.8 if I’m looking for maximum sharpness and resolution.”
“On the other end, f16, the smallest aperture, is useless at 35mm or for DSLRs. Diffraction, a kind of distortion that happens when light passes through small holes, destroys images at f16. You might rule out using f11 for the same reason.”
“Don’t know the best aperture of your 35mm camera? Fall back on the old rule my father taught me back in the 1970s: the optimum aperture for sharpness and detail is about two stops away from wide opened. That is, on a lens with a maximum aperture of 2.8, you’ll probably get the best results at 5.6.”
Timely and useful advice. Matt and I were just involved in a discussion about this over the weekend while we were shooting State of the Apartment on the Canon 5D Mark II. Now we know better. :)
Read the full article here.
Shuling Yong 