DOF: When is shallow too shallow?

CanonFanBoy

EOS 5D SR
Jan 28, 2015
4,087
1,631
Irving, Texas
This is mainly for you portrait shooters.

I have found the 135 f/2L and my 24-70 f/2.8L II to be my favorite portrait lenses. I bring those two particular lenses up because they do a great job to my eye, so I use them most. I also have the 70-200 f/2.8L IS II, but I always defer to the 135L. Admittedly, I don't get much practice with anything I have.

Here's my problem, if it can be called a problem: Balancing bokeh and DOF... then how do you do this with a faster lens?

We all see the portraits where one eye is in focus and then the subject just starts to melt into the background. They are nice. However, stopping down to get a deeper depth of field causes the bokeh to not be as smooth.

Is there too much emphasis on creamy soft bokeh and extremely shallow depth of field? I see some beautiful photos with both eyes in focus and the background not so smooth. They are still great photos. Some of them are quite breathtaking (Some portraits by Pookie come to mind.).

All this makes me wonder: If a person has flash, then why the need for anything faster than f/2 if the faster lens is going to be stopped down anyway (Though I shoot the 135 wide open with flash all the time.)?

My question mainly concerns portraits. I know there are many more uses for fast primes than portraits.
 

privatebydesign

Would you take advice from a cartoons stuffed toy?
Jan 29, 2011
7,906
1,048
119
For environmental portraits I like f2, f2.2, with the 35mm. For head and shoulder work I tend to use the 100L Macro and generally around f8, I'm much more interested in eyes and expression than bokeh and if I find the background distracting I'll change my perspective to adjust for it. For candid/street/walk around I'll use the 24-70 f2.8 between 2.8 and 5.6.
 

ScottyP

EOS 7D MK II
Feb 18, 2012
792
0
Pennsylvania, USA
The super shallow DOF look can be overdone. I have taken shots of people where part of the face is deliberately OOF and had the subjects think I screwed something up. One or two shots in a bunch with that look is cool, but I don't think many regular people would really want all of their portraits to have one eye out of focus and no discernible ears to be found.

If you want more blurry backgrounds you can just make sure the background is farther away instead of always opening the lens to a super large aperture.

Flash is fine but is very limited in range, and the light falls off precipitously with distance (inverse square law). If your exposure setting requires flash on your subject (and you are not shooting in a studio), then ambient light will be too dim and so anything farther away than your subject will be too dark.
 
P

Pookie

Guest
CFB, this isn't really about how much/less DOF is correct. It's about what you're trying to accomplish with the image and the effect you're looking for.

1.2 @ 3 feet or 1.2@ 50 feet. It's the distance that you need to consider and what you want in focus or not. Do you want to isolate your subject or not? Many make the mistake of just cranking wide open because they saw a great image somewhere and never consider the implication of that act. I always think about what I want first and then plan accordingly. Your best bet is to think of the final image and use the tools you have to accomplish it. Sometimes you want some butter, sometimes you want crispy. Portraiture comes in many different flavors and formulas don't work once you get past the basics. If you're using a strobe and want a thin DOF then use a ND filter... but is that what you want is the more important question.

And speaking of tools...that 70-200 will work wonderfully for portraiture. Sometime better than the 135. I have the 200 f/2 but honestly you can get a very similar look with all the lenses you mention. It's why I've said here many times, great lens but not necessary. It's heavy and a PITA to lug around everywhere... especially when you have a 135 or 70-200 or 85 or 50...etc. I know that won't stop the blood lust though ;)

Sure it's nice to have loads great lenses at your disposal but knowing how to accomplish what you want is a better use of your time and money. Many lenses can serve multiple purposes and help you narrow down the lens swaps and camera juggling (and save you 30-50lbs off your back). I guess my point here... lenses and cameras are just tools in the bag and they won't do you a bit of good if you don't know the why's and how's.

And thanks...
 

stevelee

FT-QL
Jul 6, 2017
1,250
281
Davidson, NC
For my taste, 135mm is a wee bit too telephoto for portraits. Maybe if a person had really big facial features, I might want to flatten them by getting farther away and using a telephoto.
 

geekpower

EOS 80D
Feb 22, 2015
187
0
+1 to thinking about distance, as Pookie points out

if you have control over all aspects of the shot, then background blur is influenced more by the relative lengths of the foreground and background than by the aperture. for example, if your subject is close to the camera, but far from the background, the background will tend to blur even when stopped down, but if your subject is far from the camera, and close to the background (example, standing in front of a brick wall) then blurring the background will be almost impossible, even wide open.
 

rfdesigner

EOS 6D MK II
Sep 12, 2014
876
0
New Forest, UK
sites.google.com
I have often thought that a "constant DOF" mode would be useful... get in close and the aperture shuts down to keep maybe a 1ft/30cm depth of field regardless.

Mostly we don't have time to try and work out what aperture will give us the correct DoF, which is why I love my EG-S screen so much.. I can see my DoF in the viewfinder (more or less) and so I get a warning if I try to over do things.
 

Jopa

EOS 6D MK II
Dec 11, 2015
1,056
0
You can actually have both bokeh and full subject in focus with this:
https://petapixel.com/2014/07/28/bokeh-problem-focus-backgrounds-hold-can-get-fast-prime/

;D fake bokeh FTW!
 
Jan 18, 2016
6
0
Depth of field is too shallow when you loose resolution and details on your subject. Since digital/internet, very shallow DOF looks somewhat ok because of the low resolution of photos displayed on today's low resolution screens. Blurry parts become sharper when resized. But when printed big, you start to think that it looks wrong when most of the subject seem to swim in a pool of their own blur. Basically when there's more blur than actual sharp subject, it's a waste of ink.

Traditionnally in portraiture, you want the visible part of your subject sharp, especially the contour/silouhette/edge against a blurred/non-distracting background. That creates the separation and make your subject pop-out 3D like. With a too shallow DOF, the background is indeed smoother, but so is the subject: separation is not increased (in fact, it is visually decreased because, as you said, the subject start to melt in the background).
A human head depth is around 20 cm, so your DOF needs to be at least ~15cm (5 in front, 10 back) so you get all front parts of the face + half of the head to get the edges in sharp focus. Including the body, you may want a DOF of 20~60cm depending of the size and position of the subject.
Now, just like macro photography, the closer you get, the narrower the aperture needs to be for a decent DOF, but here is a thing: the tighter the framing, the less background you get, therefore the less important the background/subject separation needs to be. So a shallower than the theorical 15cm DOF for a headshot is still acceptable, as long as the entire face remains sharp and not just the eyes with some bits here and there.

Personnally, I usually shoot at the following apertures that I set as standard for myself:
Headshot: f/8 (7cm DOF)
Head and shoulders: f/5.6 (10cm)
Medium (at the waist): f/4 (14 cm)
American (above knees): f/2.8 (20cm)
Italian (under knees): f/2 (28cm)
Full body: f/1.4 (40cm)
(Coincidentally, shooting distances are increased/decreased by 1.41 - square root of 2 - for every other of those standard framings in portraiture, just like standard lens focal length and extenders, and so are my chosen f/numbers and therefore resulting depth of field).

Now that it's understood that apertures for controlling DOF are more or less set in stone depending on the size and distance (given for a focal lenght) to your subject, how do you get a even smoother and more blurry background? That is done with distances.
First, the more you physically separate your subject from the background, the more... separated your subject will be from the background (duh!). With greater distance between subject and background, there will be more of the former, but it will be much more blurred.
Second, working with long focal lengths to force yourself further from your subject. Backgrounds are magnified = less of it in the frame and magnified blur. This works only in conjunction with the first condition: if there's no distance between subject and background, then there's no perspective to compress.
Of course, every of those things is not always possible in all situations. Having to back up constantly gets really annoying very quickly, very compressed/flattened portraits you get with long lenses are impressive at first, but they feel unnatural and cold and you'll eventually get bored by the same look. Photography is always compromise and there are much more important things than blur in portraiture, so don't get too obsess with the bokeh thing.

About fast lens and portraiture, they are great for:
- full body shots: at longer framing distances, DOF gets much deeper that a standing human body, so no problem with very large apertures. Just don't be afraid to stop the aperture down if you want a decent DOF as you get closer, it is not forbidden.
- available light portraiture: you are willing to trade subject sharpness/separation for a cleaner image. In return you also get impressive bokeh.
- stopping motion for candid/unposed portraits: they are usually done with some distance, so depth of field don't get too shallow and you are allowed fast shutter speed with low ISO settings.
 

Labdoc

EOS 80D
Mar 23, 2016
130
18
60
USA
Thanks abcd1234, took a while to type all that and it's good to see what other people do, very informative, but I was wondering, how about guys like me?
Italian/American = ?

Cheers

abcd1234 said:
Personnally, I usually shoot at the following apertures that I set as standard for myself:
Headshot: f/8 (7cm DOF)
Head and shoulders: f/5.6 (10cm)
Medium (at the waist): f/4 (14 cm)
American (above knees): f/2.8 (20cm)
Italian (under knees): f/2 (28cm)
Full body: f/1.4 (40cm)
 

sulla

EOS RP
Dec 31, 2012
246
14
Austria
www.flickr.com
I generally max out at 2.8 for portraits at typical distances, because I find the DOF to be already shallow enough to isolate the subject from background. Anything wider than 2.8 will achieve a look with out-of-focus ears and noses that must be used carefully not to be overdone and irritate people. (There is a very impressive shot of a boxer taken with the Leica Noctilux at f/0.95 that has the eyes in perfect focus, but already the front end of the helmet blurred strongly, very impressive shot, but I would not like every portrait to be like this.)

For studio portraits, i.e. with flashes, bells and whistles, I very often close the aperture to f/8, and then, really, any lens will do, but in the studio you can also control background blur by adjusting subject to background distance... I almost exclusively use the 70-200 or a 100 macro for those general portrait purposes. I do use faster lenses to achieve ultra-low-DOF in well lit situations, but only seldomly.

I use fast primes mainly for photography (portraits, but not only) in low light, really, because their shallow DOF conveys the atmosphere of available low light conditions very nicely, I believe. I like available light portraits a lot. I have done a few sessions in a studio lit by candlelight only, and found shallow DOF to suit those situations well.
 

Besisika

How can you stand out, if you do like evrybdy else
Mar 25, 2014
638
26
Montreal
Labdoc said:
Thanks abcd1234, took a while to type all that and it's good to see what other people do, very informative, but I was wondering, how about guys like me?
Italian/American = ?

Cheers
You tilt the camera 45% around its axis so that left leg is cut under the knee and right leg is cut above the knee. This way you avoid cutting the joints.
 

privatebydesign

Would you take advice from a cartoons stuffed toy?
Jan 29, 2011
7,906
1,048
119
rfdesigner said:
I have often thought that a "constant DOF" mode would be useful... get in close and the aperture shuts down to keep maybe a 1ft/30cm depth of field regardless.

Mostly we don't have time to try and work out what aperture will give us the correct DoF, which is why I love my EG-S screen so much.. I can see my DoF in the viewfinder (more or less) and so I get a warning if I try to over do things.
That is easy, just maintain the desired aperture and keep the subject the same size within the frame as you zoom (so you have to move) and the DOF will remain constant.
 
Jan 18, 2016
6
0
Labdoc said:
Thanks abcd1234, took a while to type all that and it's good to see what other people do, very informative, but I was wondering, how about guys like me?
Italian/American = ?

Cheers
Heh, just like Besisika said :p

Note about those framing standards. American (also known as 3/4 length), cuts above the knees of a standing person, usually, you want most of the thighs, it looks better and more balanced. Italian, under knees, works well with women wearing dresses and skirts, but in opposite to American framing, you want little as possible of the calves and rest of the legs, because it will look like you cut the foot out and just like cutting hands/fingers , that's no good.
 

Besisika

How can you stand out, if you do like evrybdy else
Mar 25, 2014
638
26
Montreal
CanonFanBoy said:
All this makes me wonder: If a person has flash, then why the need for anything faster than f/2 if the faster lens is going to be stopped down anyway (Though I shoot the 135 wide open with flash all the time.)?
If I negate this sentence partially then it says "if a person doesn't have a flash, then it is OK to shoot with a lens faster than 2.0".
Based on that, I assume that you are referring to shooting indoor when light is not powerful enough for you to shoot at 5.6 without a flash. I assume as well that you are not referring to studio work, otherwise you wouldn't want to knock out the background using bokeh.
Please let me know if I am wrong, because my answer wouldn't make sense at all.

Shooting indoor, DOF looses the battle and bokeh wins it.
There is no way for the background not to scream "look at me" when shooting with a telephoto at 5.6 or 8 indoor. That is because of the rapport working distance versus background distance, unless it is a pure head-shot. A background that allows you for that must be an arena.
Wanting to knock out the background, because it is not the subject of a portrait, you have no choice other than shooting with shallow DOF. This is why I don't see the reason for you to begin to think that 2.0 on your 135 is inappropriate.
The second reason, and for me that is actually the main, is because I prefer balancing my ambient light with the flash, by gelling it. At 5.6 if I put the flash close to subject the only way for me to light up my background with the same flash is if the background is very close, which will make that background very in focus. Yes, you can light up the background with another flash however you will have to have that place for you alone and nobody else is allowed to be in your shot.
You can bounce as well the flash so that it can be put further and thus illuminating bigger space but again you must be alone to do that.
So for me, shooting indoor, I have to use shallow DOF, in particular when shooting portrait (bride and her father in front of a dancing party for example).
My favorite lens for the job is the 85mm 1.2, and depending on the room as well as the crop, I put it at 1.4, 1.6 or 2.0 (at max 2.8)

If you want to shoot at 5.6, with blurred background and incorporate ambient light then you must shoot whether outside or under an open shade (parking lot for example, or abandoned factory) and here, yes, balancing bokeh and DOF is required depending on the look you want to achieve and the environmental elements of your chosen location, but I assumed that this is not what you are interested in.
 

Pippan

EOS M50
Mar 30, 2016
45
0
abcd1234 said:
Depth of field is too shallow when you loose resolution and details on your subject. Since digital/internet, very shallow DOF looks somewhat ok because of the low resolution of photos displayed on today's low resolution screens. Blurry parts become sharper when resized. But when printed big, you start to think that it looks wrong when most of the subject seem to swim in a pool of their own blur. Basically when there's more blur than actual sharp subject, it's a waste of ink.

Traditionnally in portraiture, you want the visible part of your subject sharp, especially the contour/silouhette/edge against a blurred/non-distracting background. That creates the separation and make your subject pop-out 3D like. With a too shallow DOF, the background is indeed smoother, but so is the subject: separation is not increased (in fact, it is visually decreased because, as you said, the subject start to melt in the background).
A human head depth is around 20 cm, so your DOF needs to be at least ~15cm (5 in front, 10 back) so you get all front parts of the face + half of the head to get the edges in sharp focus. Including the body, you may want a DOF of 20~60cm depending of the size and position of the subject.
Now, just like macro photography, the closer you get, the narrower the aperture needs to be for a decent DOF, but here is a thing: the tighter the framing, the less background you get, therefore the less important the background/subject separation needs to be. So a shallower than the theorical 15cm DOF for a headshot is still acceptable, as long as the entire face remains sharp and not just the eyes with some bits here and there.

Personnally, I usually shoot at the following apertures that I set as standard for myself:
Headshot: f/8 (7cm DOF)
Head and shoulders: f/5.6 (10cm)
Medium (at the waist): f/4 (14 cm)
American (above knees): f/2.8 (20cm)
Italian (under knees): f/2 (28cm)
Full body: f/1.4 (40cm)
(Coincidentally, shooting distances are increased/decreased by 1.41 - square root of 2 - for every other of those standard framings in portraiture, just like standard lens focal length and extenders, and so are my chosen f/numbers and therefore resulting depth of field).

Now that it's understood that apertures for controlling DOF are more or less set in stone depending on the size and distance (given for a focal lenght) to your subject, how do you get a even smoother and more blurry background? That is done with distances.
First, the more you physically separate your subject from the background, the more... separated your subject will be from the background (duh!). With greater distance between subject and background, there will be more of the former, but it will be much more blurred.
Second, working with long focal lengths to force yourself further from your subject. Backgrounds are magnified = less of it in the frame and magnified blur. This works only in conjunction with the first condition: if there's no distance between subject and background, then there's no perspective to compress.
Of course, every of those things is not always possible in all situations. Having to back up constantly gets really annoying very quickly, very compressed/flattened portraits you get with long lenses are impressive at first, but they feel unnatural and cold and you'll eventually get bored by the same look. Photography is always compromise and there are much more important things than blur in portraiture, so don't get too obsess with the bokeh thing.

About fast lens and portraiture, they are great for:
- full body shots: at longer framing distances, DOF gets much deeper that a standing human body, so no problem with very large apertures. Just don't be afraid to stop the aperture down if you want a decent DOF as you get closer, it is not forbidden.
- available light portraiture: you are willing to trade subject sharpness/separation for a cleaner image. In return you also get impressive bokeh.
- stopping motion for candid/unposed portraits: they are usually done with some distance, so depth of field don't get too shallow and you are allowed fast shutter speed with low ISO settings.
Thank you so much for this explanation of DOF in portraiture, it is by far the clearest and most helpful I've ever read. I'm going off now to practice on my children ...
 
Jan 18, 2016
6
0
Pippan said:
Thank you so much for this explanation of DOF in portraiture, it is by far the clearest and most helpful I've ever read. I'm going off now to practice on my children ...
You're welcome, hope that helps!

A little bit of explanation about the apertures I use for each framing:
- For full body, you get f/1.4 which is about the widest you can get with DSLR lenses (with few exeptions).
- Making your way closer to american framing, this is the tightest framing where most of the body is in the frame while still having an at least equal amount of background. So this the tightest framing where I still want the edges of the subject nicely sharp. F/2.8 gives you just that with a DOF of ~20cm.
- F/5.6 for head & shoulders shots again works well, most of the subject is in sharp focus, especially women with their big feminine parts.
- And finally headshots: distance between human eyes is around 6cm. If the face is turn at a 45 angle left or right, the depth between the two eyes therefore is around 4.3cm (like FF diagonal!). And guess what? F/8 allows just enough DOF to get both eyes in focus (considering perfect focus is achieved): about 2.4cm of sharpness in front of the point of focus, and 4.6cm behind, reaching the furthest eye. Not to mention that f/8 is about the sharpest and narrowest aperture you want to use before diffraction kicks-in in our today's 30-ish MP cameras.

See how everything seems to fall magically into place? Plus, those 1-stop increments make it easy and fast to remember during actual shootings. Of course, those numbers aren't strict rules, there's nothing wrong if you want to achieve something else playing with more or less depth of field, and f/5.6 or f/8 are not ideal apertures to work with in available/low light for exemple. But I believe those are very good numbers.
 

CanonFanBoy

EOS 5D SR
Jan 28, 2015
4,087
1,631
Irving, Texas
Pookie said:
CFB, this isn't really about how much/less DOF is correct. It's about what you're trying to accomplish with the image and the effect you're looking for.

1.2 @ 3 feet or 1.2@ 50 feet. It's the distance that you need to consider and what you want in focus or not. Do you want to isolate your subject or not? Many make the mistake of just cranking wide open because they saw a great image somewhere and never consider the implication of that act. I always think about what I want first and then plan accordingly. Your best bet is to think of the final image and use the tools you have to accomplish it. Sometimes you want some butter, sometimes you want crispy. Portraiture comes in many different flavors and formulas don't work once you get past the basics. If you're using a strobe and want a thin DOF then use a ND filter... but is that what you want is the more important question.

And speaking of tools...that 70-200 will work wonderfully for portraiture. Sometime better than the 135. I have the 200 f/2 but honestly you can get a very similar look with all the lenses you mention. It's why I've said here many times, great lens but not necessary. It's heavy and a PITA to lug around everywhere... especially when you have a 135 or 70-200 or 85 or 50...etc. I know that won't stop the blood lust though ;)

Sure it's nice to have loads great lenses at your disposal but knowing how to accomplish what you want is a better use of your time and money. Many lenses can serve multiple purposes and help you narrow down the lens swaps and camera juggling (and save you 30-50lbs off your back). I guess my point here... lenses and cameras are just tools in the bag and they won't do you a bit of good if you don't know the why's and how's.

And thanks...
Sage advice as usual! Thanks Pookie.
 

Viggo

EOS 5D SR
Dec 13, 2010
4,212
773
I shoot most or all of my portraits with my Siros L and wide open aperture, but change distance and focal length to control DOF. Simply because I feel that wide open pop goes away even a stop down so I want to keep it. But if I want my subject sharp, I use the 35 and use little distance instead of longer FL and stop down. When I use my flash and a a “studio background” where bokeh doesn’t matter I can stop down a bit more, but often closer with longer FL.