DOF advise when shooting people

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firoz

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Hi all,

I am still learning and getting to grips with DOF. I was wondering about DOF when shooting people. I think I understand this but guess I just needed to confirm my understanding and get some advice.

When shooting people if I wanted to focus on the face of the subject I will usually have the AF point around the eye and a large aperture. However if I wanted to focus on the same subject but have their whole body in focus and sharp - would I step back/zoom out with a slightly higher f stop? Would I again use one AF point focusing on eyes.

I would at this stage start playing around with this on my camera, but I'm on the computer and thought I would ask!
 
I'm sure someone will come along in a moment with a better explanation, but DOP extends equally infront and behind the point at which you focus and the depth of that focus is dependant on focal length and aperture.
 
I would usually stop down a little to get a wider depth of filed but wider angle, further from subject will also make it wider.

As for the out of focus element being equal in front and behind, it is actually (if memory serves me correct) about 1/3 in front and 2/3 behind. Have a play with DOF master the online tool and see ;)
 
mark1616 said:
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As for the out of focus element being equal in front and behind, it is actually (if memory serves me correct) about 1/3 in front and 2/3 behind. Have a play with DOF master the online tool and see ;)
Click to expand...

I know why I said what I said but of course the in focus distance is going to extend further behind than in front.
 
a higher f number (smaller aperture) will result in a larger depth of field and help keep more of the face in focus. Focusing on the eyes is still a good place to start. If you step back and zoom in further, you will compress your depth of field and require a higher f number, which will ultimately require more light (higher ISO or slower shutter).
 
mark1616 said:
Have a play with DOF master the online tool and see ;)
Click to expand...

stay away from DOF master...
it will warp your brain

just grab a mate and do some tests, you'll soon figure it out- don't waste time looking at stupid numbers and calculation tables
 
The DOF master will quickly show you the relationship between shooting distance focal length and DOF... In other words, one of the most effective creative tools in the box is using your feet and re framing the shot
 
Richard King said:
The DOF master will quickly show you the relationship between shooting distance focal length and DOF... In other words, one of the most effective creative tools in the box is using your feet and re framing the shot
Click to expand...

What he says! :)
 
hoolio said:
I'm sure someone will come along in a moment with a better explanation, but DOP extends equally infront and behind the point at which you focus and the depth of that focus is dependant on focal length and aperture.
Click to expand...

It is not necessarily equal in front and behind.
 
mark1616 said:
I would usually stop down a little to get a wider depth of filed but wider angle, further from subject will also make it wider.
Click to expand...

I'm stumped by this.

Stopping down will increase the depth of depth of field. On standard, i.e. not shift, lens baby et al, lenses the width of depth of field typically extends across the width of the field of view. I'm presuming that you said width instead of depth in this instance.

Where I'm completely lost is how stopping down gives you a 'wider angle'. Can you explain what you mean?
 
NorthernNikon said:
I'm stumped by this.

Stopping down will increase the depth of depth of field. On standard, i.e. not shift, lens baby et al, lenses the width of depth of field typically extends across the width of the field of view. I'm presuming that you said width instead of depth in this instance.

Where I'm completely lost is how stopping down gives you a 'wider angle'. Can you explain what you mean?
Click to expand...

mark1616 said:
I would usually stop down a little to get a wider depth of filed but wider angle, further from subject will also make it wider
Click to expand...

I will reword as I was dead tired when I wrote that, although it does still make sense if you add lens after 'but wider angle'.

I would usually stop down a little to get a wider/greater depth of filed. Other ways to get get a wider depth of field are to use a wider angle lens and to get further away from subject.
 
Lol, thanks everyone, I have been playing around with this and have a good grasp now......I think!
 
mark1616 said:
If you look from the side it is wider ;) but yes probably deeper.
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It might seem pedantic, but there is a big difference between the two and when referring to dimensions it can mean the difference between something fitting or not if you get them mixed up!

In relation to depth of field, narrow or wide DOF is achievable with tilt lenses.
 
NorthernNikon said:
It might seem pedantic, but there is a big difference between the two and when referring to dimensions it can mean the difference between something fitting or not if you get them mixed up!

In relation to depth of field, narrow or wide DOF is achievable with tilt lenses.
Click to expand...

As pedants go you're not very pedantic :D

When speaking about depth of field (or anything else for that matter) the words wide and narrow are incorrect. Depth can be shallow or deep - maybe even short or long - but not narrow or wide as those are words that relate to width.
 
Subscribing to this topic. Any online tool saying me that 85mm on 1.2 gives you 4cm DOF at 2meters and 6cm on 2.0. I was shooting portraits yesterday. I can hardly keep eyes in focus on 2.0-2.8. DoF is much less then 4cm, maybe only 4mm? so we need another calculator for portraits. I found that i need fight my desire to shoot wide open on distances up to 3 meters on wider then 2.8. Unless model not looking straight into camera.
 
Ok. found it. In online calculator circle of confusion parameter used as 0.03mm.
For 5Dmk2. Or any full size 21mpx we have 36mm on 5616 pixels. That is 0.006mm. 5 times less.

http://www.dofmaster.com/equations.html
http://www.dofmaster.com/digital_coc.html

In wiki:
Using the “Zeiss formula”, the circle of confusion is sometimes calculated as d/1730 where d is the diagonal measure of the original image (the camera format). For full-frame 35 mm format (24 mm × 36 mm, 43 mm diagonal) this comes out to be 0.024 mm. A more widely used CoC is d/1500, or 0.029 mm for full-frame 35 mm format, which corresponds to resolving 5 lines per millimeter on a print of 30 cm diagonal. Values of 0.030 mm and 0.033 mm are also common for full-frame 35 mm format. For practical purposes, d/1730, a final-image CoC of 0.2 mm, and d/1500 give very similar results.
Click to expand...
 
This is where the misunderstanding starts, in a similar way to crop factor & focal length

Circles of least confusion are a optical quality. A lens is a lens is a lens - its qualities dont change because you pop it on a crop camera, and then on the full frame

The sensor pixel density is red herring too the optical qualities of a lens dont change if you change the sensor the image the lens produces lands on
 
In monkey terms:
F2 = very little in focus - lots of blur except the point of focus, visual example only 1 eye when subject facing straight at camera

F8 = lots in focus - still blur but generally in a head shot eyes, ears and hair as well as some background detail will be notably detailed.

F4 or F5 is usually the norm for getting both eyes in focus but on a long focal length this theory can fall flat on its arse when close ups of a face are employed.

Want to learn more grab your camera and get shooting and compare results :)
 
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