An artist decides what is important on his canvas and emphasizes that—“the center of interest”—over the other supporting elements in the scene. The painter may do this with color, perhaps using a brighter color or with more directional, dramatic, lighting on his main subject. The painter may paint his main subject with sharp detail and obscure or mute detail in the background.
It is our job as an artist to direct where the viewer looks in our images. The way we do that in photography is with what is sharp against what is un-sharp (out of focus).
We create that with our point-of-focus and depth-of-field, which is controlled by the aperture we choose in concert with the lens focal length we pick.
These choices are the most important artistic controls we have in photography.
The core problem with the camera’s Auto Modes (don’t even get me started on the “P” mode!) is that the camera does not know what it’s being pointed at; it does not know what the subject is. Therefore, it can’t know the best f-stop/shutter-speed for that subject—just like ti could not automatically pick a focal length for your zoom lens!
What aperture to use and why?
Forty plus years doing artistic photography (30 years as a full time professional) has taught me that each artist settles on favorite apertures, that suits their style, based on what the subject is. In addition I will change my aperture if my subject’s orientation to my camera changes…
f2.8 @ 1/250sec., ISO 800; lens @ 200mm
My preferred aperture is f4.5 when doing portraits of individuals. Why? I’ve found that it’s the best aperture to maintain sharpness in BOTH eyes in a 2/3rds view of the face, while still creating a nice shallow depth-of-field (using my 200mm lens) that will knock the background out of focus for some nice Bokeh.
However, in the portrait above of the boy, he started exploring and went into profile so, not having to worry about that far eye, I went to f2.8 (bumping the shutter speed up to maintain correct exposure) to really enhance my background Bokeh.
And, just to show you that you don’t need really wide apertures to get good Bokeh…
f5.6 @ 1/125 sec., ISO 400; Lens @ 200mm
Bokeh is mostly about focal length and distance between the subject and the background. In my fine art images depth-of-field is often more critical especially when I move in doing close-ups of nature—since as you move closer to your subject (at the same f-stop) your depth-of-field DECREASES.
f6.3 @ 1/250 sec., ISO 400; Lens @ 82mm
In this detail of the Ice crystal laden leaves of a weeping willow I wanted as much depth-of-field as I could get while still keeping the background (that same tree) soft to reduce its busy nature.
Then sometimes I want maximum Depth-of Field…
f11.0 @ 1/640 sec., ISO 400; Lens @ 95mm
In this Black and White art piece I wanted everything crisp and razor sharp because I knew this subject would be excellent in B&W.
In our fine art photography we often build an image in layers; it’s called foreground, mid-ground (usually the subject), and background. This is how we create depth, interest and three-dimensionality.
f8.0 @ 1/350 sec., ISO 400; Lens @ 79mm
The sailboat regatta scene had some nice layers that I wanted sharp. Starting with the floating seaweed in the foreground the sunlit boats (mid-ground) and those great boats, lost in the fog, in the background; I used f8.0, focused on the seaweed, to get the foreground and mid-ground both sharp.
Knowing your depth-of-field with different apertures at given focal lengths is important in general, but it’s CRITICAL when doing group portraits. When I do portraits outside I always try to make my backgrounds as soft as possible to make the people stand out—and if I can get some Bokeh, even better!
So, the tricky part is to stop down just enough, getting enough depth-of-field to cover ALL the subjects—especially when we place them at different distances from the camera for a nice composition. I use f6.3 on many of my single family groups. If the family is large I will go to f7.1 for more depth-of-field.
One of my favorites…
f6.3 @ 1/125 sec., ISO 400; lens @ 115mm
In the above example I know that at 6.3 with my lens at 115mm (I’m Usually at a longer focal length, like 150mm, if I can back-up) at a distance of 25 feet my depth-of-field is 5.47 feet (using my full-frame Canon 5D MKII).
As you can see the creative use of aperture and the depth-of-field it can create (along with lens choice—more on that later!) is something you don’t want to leave up to any Auto Mode. Do something creative and show me your results!
Next, in Part 4, I’ll get into creative use of your Shutter Speed. Fun Stuff! ’Tis next week…
Author: Jerry W. Venz, PPA Master Photographer, Craftsman
Training Site: http://www.LightAtTheEdge.com
Client Site: http://www.TheStorytellersUsa.com
NOTE: Go to: http://www.DOFMaster.com and try their easy to use Depth-of-Field calculator for your camera/lens/f-stop/distance combinations. It’s vital information for the professional and very educational for the amateur.