I understand how depth of field works, I just have a hard time learning to control it and use it when I need it. Is there any good tips or videos to help me get better.
ShotbyRon wrote: I understand how depth of field works, I just have a hard time learning to control it and use it when I need it. Is there any good tips or videos to help me get better.
i have to question if you really know how DOF works? anyway
3 tools to control DOF:
1. lens aperature-larger f stop = smaller DOF
2. lens focal length-longer focal length = less DOF
3. focusing distance-closer the focused subject is = less DOF
i have to question if you really know how DOF works? anyway
3 tools to control DOF:
1. lens aperature-larger f stop = smaller DOF
2. lens focal length-longer focal length = less DOF
3. focusing distance-closer the focused subject is = less DOF
use any or all in combination
1 & 3, yes. But focal length does not influence depth of field.
ShotbyRon wrote: I understand how depth of field works, I just have a hard time learning to control it and use it when I need it. Is there any good tips or videos to help me get better.
I more or less use the Bryan Peterson method:
Determine how deep your field of focus needs to be. If you have a scene where only the foreground interest is desired and the rest can be safely blown out of focus, look for something in the f/1.2-4 range.
For something a little deeper, like shots of couples, with not much emphasis on the background I look for f/4-6.3
If you need a lot of depth to your scene, such as showing a foreground of a model, standing in front of a pool of water with an interesting waterfall in the background, you want to look between f/16-32 to keep it all in focus.
For the rest, where depth of field is not a real concern, you have the classic "who cares" apertures of f/8-11
1 & 3, yes. But focal length does not influence depth of field.
No, but it does in a practical sense influence the DOF you will be able to achieve. For someone trying to figure out how to control DOF, it's an important factor to consider nonetheless.
NothingIsRealButTheGirl wrote: If focal length magnifies the out of focus background then it appears to have an effect.
A long lens will allow you to stand farther away from the subject, and that can influence how the out of focus area appears. But the depth of field is basically the same of the framing is identical.
A long lens will allow you to stand farther away from the subject, and that can influence how the out of focus area appears. But the depth of field is basically the same of the framing is identical.
The calculator you referred to shows that DoF depends of focal length.
NothingIsRealButTheGirl wrote: I think the question might be -
what helps me isolate the subject most?
Assuming that I'm going to frame people in similar ways whether I am far away with a long lens or closer with a shorter one.
Definitely. A longer lens allows you to stand farther away, which can influence perspective. I'm not telling anyone to shoot headshots with a 24mm lens!
Mike Kelcher
Posts: 11,629
Minneapolis, Minnesota, US
ShotbyRon wrote: I understand how depth of field works, I just have a hard time learning to control it and use it when I need it. Is there any good tips or videos to help me get better.
Here's what I teach my students....not because it's "factual" but because it helps them to remember how it works...
If you focus on your subject and use an aperture of F/... 1.4 ... then everything 1.4" in front of and behind the subject will be in focus.
2.8 ... then everything 2.8" in front of and behind the subject will be in focus
4 ... then everything 4" in front of and behind the subject will be in focus
5.6 ... then everything 5.6" in front of and behind the subject will be in focus
8 ... then everything 8" in front of and behind the subject will be in focus
11 ... then everything 11" in front of and behind the subject will be in focus
16 ... then everything 16" in front of and behind the subject will be in focus
22 ... then everything 22" in front of and behind the subject will be in focus
Again...this is not the "depth of field Bible" but it's a good way to remember how lens openings affect depth of field. I know these examples aren't even close....that's not my point. My examples are merely a "tool" to remember how it works.
That's not the entire story though...
The closer the subject is the shallower the depth of the focus field will be. At infinity...the depth of the focus field is deeper.
Longer lenses have a tendency to compress the depth of the focus field. (ie: make it shallower).
Wide angle lenses have a tendency to make the depth of the focus field deeper.
I'm fairly certain that if you understand and remember the above...you'll be able to gain the control you need for the vast majority of situations.
A long lens will allow you to stand farther away from the subject, and that can influence how the out of focus area appears. But the depth of field is basically the same of the framing is identical.
SPV Photo wrote: 1 & 3, yes. But focal length does not influence depth of field.
The problem here is that you're providing a half-answer.
While a 35mm F/2.8 lens may give the subject the same DOF as a 300mm F/2.8 lens (same framing), the "subject isolation" or "creamed background" provided by the 300mm lens will be far superior thus creating the optical illusion of a shallower DOF, even-though by the numbers the subject's DOF is the same.
The side by side image below is not the best example, but it's close enough to illustrate the point. Both images have basically the same DOF, but the telephoto lens is able to cream out the background better and provide better "subject isolation" thus many people with an untrained eye will think it has a shallower DOF.
KonstantKarma
Posts: 2,077
Asheville, North Carolina, US
Unique Portraits wrote:
The problem here is that you're providing a half-answer.
While a 35mm F/2.8 lens may give the subject the same DOF as a 300mm F/2.8 lens (same framing), the "subject isolation" or "creamed background" provided by the 300mm lens will be far superior thus creating the optical illusion of a shallower DOF, even-though by the numbers the subject's DOF is the same.
The side by side image below is not the best example, but it's close enough to illustrate the point. Both images have basically the same DOF, but the telephoto lens is able to cream out the background better and provide better "subject isolation" thus many people with an untrained eye will think it has a shallower DOF.
The problem here is that you're providing a half-answer.
While a 35mm F/2.8 lens may give the subject the same DOF as a 300mm F/2.8 lens (same framing), the "subject isolation" or "creamed background" provided by the 300mm lens will be far superior thus creating the optical illusion of a shallower DOF, even-though by the numbers the subject's DOF is the same.
The side by side image below is not the best example, but it's close enough to illustrate the point. Both images have basically the same DOF, but the telephoto lens is able to cream out the background better and provide better "subject isolation" thus many people with an untrained eye will think it has a shallower DOF.
I don't really think I was providing half an answer. As you acknowledge the DOF is the same. Also, everyone seems to be focused on shallow depth of field. But what if you wanted a large depth of field? You don't care about the bokeh because you're trying to eliminate it. If you believed a long lens has a shallower depth of field, you might not be aware that a long lens can be used for a landscape shot where virtually everything is in focus as long as you're standing far enough away from the subject. So I'm not just being pedantic here. There is a practical reason why its important.
But I agree with the others that those are nice shots!
Also one might peruse all the iconic photographs made during the last century and a bit. If one notices, all their DOFs are not eyeball skin deep but are rigidly controlled and perfect.
ok, this has been beaten to death, but here's my take on it. Long lenses don't technically provide "less" depth of field; they just magnify the out of focus areas...
BUT
magnifying something that's blurry makes it more prominent, and gives it a larger circle of confusion, which is how we measure focus and sharpness (there's only one focal plane; there are just areas near the plane where things are "sharp enough that I can't tell they're not in focus")
so, longer lenses DO provide shallower depth of field, if you use this definition (which is the only definition that I was taught)
Mike Kelcher wrote: If you focus on your subject and use an aperture of F/... 1.4 ... then everything 1.4" in front of and behind the subject will be in focus.
etc etc
be sure to shave off the front and add to the back, as hyperfocal distances are more like 1/3 in front and 2/3 behind the subject.
Mask Photo wrote: ok, this has been beaten to death, but here's my take on it. Long lenses don't technically provide "less" depth of field; they just magnify the out of focus areas...
Well, it can magnify that part of the image whether its in focus or out of focus. In the above examples with the model, if it was shot at f/32 the background would probably be perfectly in focus.
SPV Photo wrote: Well, it can magnify that part of the image whether its in focus or out of focus. In the above examples with the model, if it was shot at f/32 the background would probably be perfectly in focus.
well, my point was that only the model's eyes are in focus, but that everything else in the image appears to be in focus because the "circles of confusion" are smaller than the camera can discern.
To clarify, every "point" in an image, where light would fall, is actually a very small circle everywhere but the plane of focus. When something is "in focus", most often it's near enough to the focal plane that its circles are smaller than the resolution of the recording device. If your lens magnifies the image, it's also going to be magnifying the circles of confusion, and thus the ones on the borderline that were just sharp enough on a 24mm lens are suddenly larger on a 50mm lens, so the image looks like it has a narrower depth of field, which it doesn't *really*. it just does *effectively*, so the shorthand is to just say that longer lenses have shallower DoF and let that be good until the pedants come running to argue moot points.
If you've got a smart phone there is an app called DOF Master. It allows you to input sensor size, focal length and aperture and will give you the DOF. It's only a buck or two.
ShotbyRon wrote: I understand how depth of field works, I just have a hard time learning to control it and use it when I need it. Is there any good tips or videos to help me get better.
The appeal of shallow DoF is that it creates contrast - not in luminance, but between the in focus and out of focus areas.
You can do the same thing with long lens compression. If you shot with a 200mm lens and had a DoF of 10 feet, but the background was 100 feet behind the model (think outdoors), the lens compression pulls the background forward - in terms of perception) and because it's so far away there will be a lot of contrast between how in focus the focused areas are to how out of focus the background is.
What that means is that you can get the look you want in a way that makes focusing much easier and with lenses that don't open as wide.
Canon 5D mark II, 70 mm f/2.8, subject at 10ft. DoF 1.03 ft
Canon 5D mark II, 200 mm f/2.8, subject at 10ft. DoF 0.12 ft
As focal length goes up, DoF goes down.
Canon 5D mark II, 200 mm f/2.8, subject at 29 ft. DoF 1.06 ft.
As you move back from the subject, the absolute value for DoF goes up, until at hyperfocal distance, DoF will be infinite.
ArtGlo wrote: 3 tools to control DOF:
1. lens aperature-larger f stop = smaller DOF
2. lens focal length-longer focal length = less DOF
3. focusing distance-closer the focused subject is = less DOF
use any or all in combination
SPV Photo wrote: 1 & 3, yes. But focal length does not influence depth of field.
You are narrowing in on a very, very specific scenario. A scenario that you didn't even bother to specify. ArtGlo is talking about basic principles and he is totally correct.
ArtGlo wrote: 3 tools to control DOF:
1. lens aperature-larger f stop = smaller DOF
2. lens focal length-longer focal length = less DOF
3. focusing distance-closer the focused subject is = less DOF
use any or all in combination
You are narrowing in on a very, very specific scenario. A scenario that you didn't even bother to specify. ArtGlo is talking about basic principles and he is totally correct.
No, I'm not talking about one specific scenario. I'm talking about his claim that focal length is a tool to control DOF. That is not true.
SPV Photo wrote: No, I'm not talking about one specific scenario. I'm talking about his claim that focal length is a tool to control DOF. That is not true.
Look at the calculation above. It solves the question once and for all. At f/2.8 and subject at 10ft: at 70 mm focal length, DoF is a foot. At 200 mm focal length DoF is inch and a half.
I guess your argument is that if you fill the frame at 70mm focal length, have DoF of one foot. Now to fill the same frame at 200mm focal length, you have to step back, and the DoF will become again roughly one foot.
SPV Photo wrote: No, I'm not talking about one specific scenario. I'm talking about his claim that focal length is a tool to control DOF. That is not true.
Shoot at 10 feet at 28mm at f/8, then shoot at 10 feet at 200mm at f/8. The second shot will have significantly less DOF.
MKPhoto has actually put together example numbers as well. I think you need to take another look. If you isolate focal length and let it be the only thing you change, it most definitely changes the DOF. (That is to say, keep your f-stop and focusing distance the same.)
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