Most competent professional photographers would never do group portraits with their lens wide-open with a f1.2, f1.4 or even an f2.8 lens. Then why do so many photographers think they can get away with using these apertures when dong an individual portrait? OK…I can get it if they’re experimenting on their personal work, but is it worth the risk of turning off a paying client to have half the clients’ face out-of-focus because they used f1.4 and only got a depth-of-field of just one inch?
Some say in defense that they wanted some good Bokeh in the background. Now, I’m a Real Bokeh Lover in my portraits, as well, but I will not sacrifice my client’s images on the altar of Bokeh! You don’t have to use those risky wide apertures to get great Bokeh—you just need to educate yourself about Depth-of-Field as it relates to Focal Length and Distance—both from your subject and the background.
I discovered over 30 years ago that good Bokeh was more about the focal length than about the aperture. That’s why my usual focal length for individual portraits is 200mm. With your lens at 200mm you simply don’t need a very wide aperture for good Bokeh…
f5.6 @ 1/125 sec., ISO 400; Lens @ 200mm
Most Bokeh lovers would not consider f5.6 a useful aperture, but at 200mm, as you can see, that background is beautiful and I have plenty of depth-of-field on the whole boy. The only negative thing about my camera set-up for the above image was the use of 1/125th sec. as my shutter speed with my lens at 200mm. When doing hand-held photography, especially with telephotos, I like to adhere to the old rule of one-over-focal length for a safe shutter speed. So, when I’m at 200mm I like to have my shutter speed at 1/200th or 1/250th sec., even though I do own a very expensive 70-200mm image stabilized lens.
So, how wide will I regularly go for good Bokeh and adequate depth-of-field? I consider f2.8 just too risky—especially with active children as subjects. Here are the numbers…
Distance: 10 feet
D.O.F. (Depth-of-Field) 1 1/2 inches
Now a depth-of-field of 1 1/2 inches can work OK, but only if your subject’s face is flat to the camera (even then their ears may be soft), but as soon as they turn their face away from the camera their far eye will go out-of-focus.
So, my preference is f4.5 for individual portraits—here are those numbers…
Distance: 10 feet
D.O.F.: 2 1/4 inches
And here’s what that looks like….
f4.5 @ 1/400 sec., ISO 800; Lens @ 200mm
Note: The other reason I use f4.5 in lieu of smaller apertures like f5.6 is that I want a higher shutter speed so that I can hand-hold my camera with more stability when I’m at 200mm.
The following image shows how distance can change the look of your background Bokeh…
f4.5 @ 1/320 sec., Iso 400; Lens @ 280mm
Compared to the first two images three things are different in my set-up here:
- I’m Farther Away from my subject; about 30 feet.
- My background is Closer to my subject; about 30 feet.
- My lens is 280mm.
Distance Changes Everything - D.O.F. & Bokeh
- Because I’m farther from my subject I’m getting more D.O.F. (e.g. when you back-up 10 feet you can double your D.O.F.)
- With my background so much closer to my subject here my Bokeh is sharper and not as soft as in the previous two images; the background was about 50 years away in the first and 25 yards away on the second image.
- The reason the background Bokeh is as nice as it is in the girl’s portrait is the addition of my 1.5x extender on my 200mm lens brings my focal length to 280mm.
More telephoto is almost always better than less!
If you want to check out YOUR settings to determine the Depth-of-Field:
Use: Their online depth-of-field calculator. (They even have an app for i-phone and i-Pad)
After you select your camera type simply plug-in your focal length, f-stop, and distance and it will calculate D.O.F. and more. It’s very educational!
’Til next week…Let me know if their is a subject you would like me to write about.
Author: Jerry W. Venz, PPA Master Photographer, Craftsman
Training site: http://www.LightAtTheEdge.com
Client site: http://www.TheStorytellersUsa.com