A Study in Aperture
I found out recently that using the maximum aperture for a lens can have deminishing returns. Simply put: it makes the image look “soft”, or otherwise out-of-focus. In this post I aim to find out find the best acceptable aperture setting for a specific lens.
The Setup
I started out using a tripod, with the same ISO and exposure compensation using a Minolta 50mm f1/7 lens. Starting at f/1.7 I worked my way up at reasonable steps to f/4.0. My aim was to compare the differences. See the shots below. The target couch cushion was set up roughly a meter from the bottom center of the tripod.
Depth-of-Field
There may be something to be said about maintaining the best DoF (Depth-of-field). However, using PhotoPills DoF Calculator proves just how wild, using a 50mm lens, an aperture of f/1.7 is. Shooting a target of 2 meters results in a depth-of-field of 16 centimeters – that’s a very narrow range! Bumping up the aperture value to f/2.8 provides a much more reasonable 27 centimeters, though still a bit narrow. Either way this allays any fears I had of losing out on that sweet, sweet bokeh, though the photos themselves illustrate that not a significant amount of Depth-of-Field is lost at that target distance of 1 meter.
Comparison
f/1.7–f/4.0
The biggest difference can be seen between the f/1.7 and f/4.0 shots. Note the increase in clarity on the pillows fabric.
f/1.7–f/2.8
At f/2.8 and above I started noticing less increase in perceived sharpness of the image, though the difference in comparison to f/1.7 was still fairly noticeable
f/2.8–f/4.0
Aside from the perceived exposure difference from what is most likely a difference in shutter speed, the overall difference does not seem as dramatic from f/2.8 to f/4.0. Personally, I’d say that f/2.8 is the clear winner in finding the best middle-ground between maximum aperture and image quality.
Individual Photos
Below is the entire collection of all the photos taken of the subject at increasing aperture steps.
Author Bastian de Byl
Modified 2019-02-11
License