Best way to focus for portraits?

10/31/2008 11:09:58 AM · #1

When shooting portraits, individuals or groups, what's the best way to focus? I'm not talking about brightly lit scenes where you can shoot at F8 and get everything just right, but those times where your lens is wide open and the ISO is cranked as high as you're comfortable with.

Do you:
manually focus?
auto focus (single point) and recompose?
auto focus using all AF points?

In the past I've used the recompose method and also using all the AF points, but not much manual. I have a portrait shoot scheduled for tomorrow and I really want to get a higher percentage with the focus where it needs to be.

Tamron SP AF 24-135mm f/3.5-5.6 AD Aspherical IF for Canon

10/31/2008 11:24:19 AM · #2

I always select my center focus point, position it directly over the closest eye, auto focus, and then recompose.

nards656

Canon EOS-300D Rebel

10/31/2008 11:31:56 AM · #3

Originally posted by skylercall:

I always select my center focus point, position it directly over the closest eye, auto focus, and then recompose.

Doesn't that waste 1/3 - 1/2 of the usable depth of field?

Nikon AF-S NIKKOR 24-70mm f/2.8G ED

10/31/2008 11:34:13 AM · #4

I don't know how much of the DOF recomposing wastes, but when shooting at 2.8 it's already fairly shallow. And how would that work for 2 or more subjects?

Citadel

Nikon D7500

10/31/2008 11:37:00 AM · #5

You can calculate DOF here: //www.dofmaster.com/dofjs.html
Then you can decide if you are going to get enough DOF for the shot.

That aside, you ALWAYS want the eyes sharp if nothing else is. That goes for anything with eyes. (i.e. animals too)

edit:
Just to throw some quick numbers together. Your 50 mm f/1.8 set at f/2.8 with a distance of 10 feet on your 40D gives you 1.29 feet of good focus. Likely you'll be further away than that but if you go to 15 feet your DOF increases to 2.94 feet which should be plenty to get a couple of people in focus.

Message edited by author 2008-10-31 11:41:32.

10/31/2008 11:46:01 AM · #6

Originally posted by Ken:

I don't know how much of the DOF recomposing wastes, but when shooting at 2.8 it's already fairly shallow. And how would that work for 2 or more subjects?

Unless your subjects face is exactly parallel with the camera one of their eyes will be closer than the other.

Tamron SP AF 24-135mm f/3.5-5.6 AD Aspherical IF for Canon

10/31/2008 11:49:29 AM · #7

Originally posted by nards656:

Originally posted by skylercall:
I always select my center focus point, position it directly over the closest eye, auto focus, and then recompose.

Doesn't that waste 1/3 - 1/2 of the usable depth of field?

About one third of the DOF will be in front of the eye. This accounts for the nose. I don't care too much if the back of their head is in focus.

nards656

Canon EOS-300D Rebel

10/31/2008 11:54:31 AM · #8

One further question, though, to me, is why are you shooting "portraits" in such low light conditions? I would do everything possible to increase available light if I were shooting a true "portrait". At least control the light on the subject, if you can't control the background.

Sorry if that's a hijack of your question.

Good point about the nose, skylercall.

10/31/2008 11:55:00 AM · #9

I played around the calculator and it seems like distance is the key for those conditions. Either that or line them up in a perfect circle with their eyes the exact same distance from the lens.

10/31/2008 12:01:17 PM · #10

Originally posted by nards656:

Not a hijack at all and a very good question.

The light tomorrow should be fine, but it seems like when the whole family is out it tends to be later and the light isn't always the greatest. Even during the day if we're out in the woods and it's overcast light is an issue. These aren't formal portraits, but I do want to get them right. I've been using the flash as a fill and it works great, but if the focus is not on the eyes it doesn't matter.

10/31/2008 02:42:11 PM · #11

Originally posted by Ken:

...Either that or line them up in a perfect circle with their eyes the exact same distance from the lens.

I didn't notice you were also asking about groups. My comments above refer to single portraits.

mpeters

Canon EOS-5D

Canon EF 50mm f/1.8 II

10/31/2008 03:07:08 PM · #12

I like to get the group ready, camera on tripod-- focus lock and fine tune the composition. I then switch lens AF/MF toggle to MF and shoot the series. Just don't forget to recheck focus if zooming or changing tripod and/or subject position. I'll usually focus just beyond the front person's eyeballs. Maybe their shirt collar or something with contrast to help the AF work in the low light.

I find my eyes don't work that great when using MF on a group so I rely on AF to get it right.

I normally use the center point AF.

10/31/2008 03:17:12 PM · #13

Originally posted by mpeters:

OK, maybe this is a silly questions, but how do you focus just beyond the front person's eyeballs? Do you compose your shot a bit off center or just recompose? What if you have two people and there is no front person?

mpeters

Canon EOS-5D

Canon EF 50mm f/1.8 II

10/31/2008 04:32:38 PM · #14

Originally posted by Ken:

Originally posted by mpeters:
I like to get the group ready, camera on tripod-- focus lock and fine tune the composition. I then switch lens AF/MF toggle to MF and shoot the series. Just don't forget to recheck focus if zooming or changing tripod and/or subject position. I'll usually focus just beyond the front person's eyeballs. Maybe their shirt collar or something with contrast to help the AF work in the low light.

I find my eyes don't work that great when using MF on a group so I rely on AF to get it right.

I normally use the center point AF.

OK, maybe this is a silly questions, but how do you focus just beyond the front person's eyeballs? Do you compose your shot a bit off center or just recompose? What if you have two people and there is no front person?

Hmmm...
With a two person head and shoulders shot, heads at similar distance from the camera--I just go with focus lock on the eyes and recompose. Mostly I use the center AF but may switch to one of the edge points to minimize recomposition focus error.

With a group 5-10 people, likely in a couple of rows, i'll still pick a focus point on the front row but I may use something besides the eyes to focus on. I like a shirt collar or the edge of a shoulder; anything with good edges/contrast. I find the AF point picks up the focus more precisely than trying to focus on an eyeball. (Keep in mind that i'm referring to a full body group shot, not a closely cropped face/shoulder shot.) I then recompose.

I figure that if 1/3 DOF is in front of the focus point, focusing just behind the front person's nose will give me the best chance of keeping everyone in focus. I'm not much of a numbers/calculations kinda guy so this is my seat of the pants method.

How many people will you be shooting?