I finally returned from holidays and began to edit some photos from a graduation I shot down in Salem OR. I came across these two portraits and thought they would show a good example of what aperture can do to your photos.
When using a DSLR and you have a lens that can shoot as low as F 2.8 you get a very very shallow depth of field (DOF). This means you have to be very precise and quick were you focus and must realize that everything in front and behind your focus point will blur very quickly. This means 2.8 can be great for portraits giving skin and background noise a very soft look while keeping the eyes sharp. It is important when shooting portraits to always focus on your subjects eyes for obvious reasons. A sharp nose and blurry eyes will not have the same impact and will leave the viewer uninterested in the photo.
The color photo and the monochrome picture were shot with almost the exact same settings as follows : F2.8 ISO 400 1/160th second. The color photo was with a length of 70mm on my 24-70 lens. The b/w photo was almost the same at 67mm. This means that I was "zoomed" in as much as I can with my lens. Zooming in and using a lens of at least 70mm creates the best portriats as well since it helps to further blur the background and tighten up the DOF focus point.
Although the b/w photo isnt my favorite composition for a portrait or nessessarily what I would desire for soft focus, I thought it was unique and shows a great example. The one eye and lips show some nice sharpness but falls a bit too quickly into blur to the farther eye. To improve this I could have used a slightly smaller aperture of 3.5? This probably would have dont the trick. However, it is subjective and sometimes something out of the ordinary makes the best photos.
PS: I uploaded both photos in a large size so you can click on them and see up close where the sharp vs blur interacts on the photo.
The color photo is what most photographers would consider more desirable since both eyes are in focus and the blur quickly falls to the background. Her face was more square to the camera (90 deg) where as the other photo was on a sharper angle. Please click on both photos and compare the difference. It is quite noticeable.
Anyways, hope you enjoy and feel free to comment