Since I stated that you can't spend too much time on aperture and depth of field — here is another take on it. The goal here was to set up a shot where we could get exact depth of field from a far point to a near point.
We chose a 50mm macro lens because at f32 it gives a full 10 inches of depth of field when focused at 24 inches. So this goes from f2.8 to f32, using a small flock of Canon flashes with ETTL metering to keep the exposure consistent. (A single small flash dies out at f22 — could not pump out enough light.)
I used an online depth of field calculator to find a lens-distance combination that would work in a portrait situation. For example, if I used a favorite lens, the 100mm macro, even at f32 there would only be 5.66" of depth of field, just about from the front of Nicole's face to the back. Not as nice a demonstration — all the shots would have looked similar. So we settled on the 50mm.
Nicole's front hand is at the limit of close focus, about 19" from the lens; her left eye is at the focus point of 24", and her back hand is at 30" from the lens. The hat in the front and the background are never in exact focus — they are here just for reference.
Bottom Line: Depth of field is harder to come by than you might think. Depth of field calculators are very educational.
Left
Right
Shooting at f2.8, 50mm, 24 inches.
The depth of field calculator says: Near focus limit = 23.6 in Far focus limit = 24.5 in Total depth of field = .91 in
Given that a 50mm is not a long lens, and 2.8 is not a very wide open aperture, compared to sexy lenses like a 1.2, it was very surprising (to me) that even at 24" from the subject we have less than one inch of depth of field!
At f4, 50mm, 24 inches.
The depth of field calculator says: Near focus limit = 23.4" in Far focus limit = 24 in Total depth of field = 1.29 in
At f5.6, 50mm, 24 inches.
The depth of field calculator says: Near focus limit = 23.1" in Far focus limit = 24.9 in Total depth of field = 1.83 in
At f8, 50mm, 24 inches.
The depth of field calculator says: Near focus limit = 22.7" in Far focus limit = 25.4 in Total depth of field = 2.59 in
At f11, 50mm, 24 inches
The depth of field calculator says: Near focus limit = 22.3" in Far focus limit = 25 in Total depth of field = 3.67 in
At f16, 50mm, 24 inches
The depth of field calculator says: Near focus limit = 21.7" in Far focus limit = 26.9 in Total depth of field = 5.22 in
At f22, 50mm, 24 inches
The depth of field calculator says: Near focus limit = 20.8" in Far focus limit = 28.3 in Total depth of field = 7.47 in
At f32, 50mm, 24 inches.
The depth of field calculator says: Near focus limit = 19.6 in Far focus limit = 30.6 in Total depth of field = 10.8 in
That is all you get for critical depth of field even with a 50mm that goes down to f32.
The creative problem here is that the background and hat LOOK pretty well focused, even though they are not. This is because they are near critical focus at f32. So if you wanted to get everything in focus from Nicole's back hand to front hand, and the background and hat way out of focus, you would need the background to be FAR back, like 20 feet, and the glove to be VERY near the lens, like 3 inches.
Shooting at f2.8, 50mm, 24 inches.
The depth of field calculator says: Near focus limit = 23.6 in Far focus limit = 24.5 in Total depth of field = .91 in
Given that a 50mm is not a long lens, and 2.8 is not a very wide open aperture, compared to sexy lenses like a 1.2, it was very surprising (to me) that even at 24" from the subject we have less than one inch of depth of field!
At f4, 50mm, 24 inches.
The depth of field calculator says: Near focus limit = 23.4" in Far focus limit = 24 in Total depth of field = 1.29 in
At f5.6, 50mm, 24 inches.
The depth of field calculator says: Near focus limit = 23.1" in Far focus limit = 24.9 in Total depth of field = 1.83 in
At f8, 50mm, 24 inches.
The depth of field calculator says: Near focus limit = 22.7" in Far focus limit = 25.4 in Total depth of field = 2.59 in
At f11, 50mm, 24 inches
The depth of field calculator says: Near focus limit = 22.3" in Far focus limit = 25 in Total depth of field = 3.67 in
At f16, 50mm, 24 inches
The depth of field calculator says: Near focus limit = 21.7" in Far focus limit = 26.9 in Total depth of field = 5.22 in
At f22, 50mm, 24 inches
The depth of field calculator says: Near focus limit = 20.8" in Far focus limit = 28.3 in Total depth of field = 7.47 in
At f32, 50mm, 24 inches.
The depth of field calculator says: Near focus limit = 19.6 in Far focus limit = 30.6 in Total depth of field = 10.8 in
That is all you get for critical depth of field even with a 50mm that goes down to f32.
The creative problem here is that the background and hat LOOK pretty well focused, even though they are not. This is because they are near critical focus at f32. So if you wanted to get everything in focus from Nicole's back hand to front hand, and the background and hat way out of focus, you would need the background to be FAR back, like 20 feet, and the glove to be VERY near the lens, like 3 inches.
