Focusing with 2.8 at 200m for portrait

The Darkroom · 08-10-2020 6:12pm #1

I've recently picked up a sigma 70-200m lens for portraiture. I'm using a Canon 5D MII with it.

I'm a newbie to this lens and portraiture photography.

I've notice that when I lock on the eyes and hold that lock then move down so that the entire body is in the frame, the eyes are blurred and the torso at the stomach is sharp.

For example I'm using a shutter speed of 1600, 2.8 at 200mm with one shot settings and still the eyes are blurring and the center piece of the of the photo at the torso is sharp.

Now, I'm not going to assume I know why this is but newbies could put it down to the lens being broken but I'm sure you guys would have a better answer.

Thank you.

DaireQuinlan · 08-10-2020 6:37pm

At 2 metres, 200mm at f/2.8 your DOF is ~1.5cm. Any movement at all will probably throw you off. Plus doing what you're doing is putting the plane of focus behind the eyes slightly. Don't know the 5D, but I assume it has multiple focal points ? Choose one that is over or close to the eye with your chosen composition and fire away.

Homer · 08-10-2020 7:00pm

Try using back button focus, as mentioned already by Daire, any slight movement with those settings will throw your focus off.

The Darkroom · 08-10-2020 7:08pm

Thanks guys. Am I better off using 4.0 to get used to it first? Is the 2.8 too large an aperture to be getting sharp portraits with?

The Darkroom · 08-10-2020 7:09pm

The distance I was at was enough to get a full body shot or from upper torso.

DaireQuinlan · 08-10-2020 7:56pm

Lots of variables, your focusing technique, whether the lens _is_ actually focusing accurately, your stance, etc etc. I'd say 2.8 is probably too open to do a focus and recompose with a 200mm at the distances you're using it at, I'd either stop down a bit or use a different focus point to nail focus without re-composing.

Heebie · 08-10-2020 8:56pm

The Darkroom wrote:

For example I'm using a shutter speed of 1600, 2.8 at 200mm with one shot settings and still the eyes are blurring and the center piece of the of the photo at the torso is sharp.

If you have enough light to use a shutter speed of 1/1600 you have enough light to use 4 or 5.6 to get greater depth of field.
But... 1600 sounds more like an ISO than a shutter speed. Depending on the camera going even higher with ISO might get noisy.

Getting closer and bit relying as much on the zoom to get close can help increase your depth of field. If you need to recompose after focusing... you need to keep the camera pointed at exactly the same angle, or the focal plane changes. (It's always parallel to the back of the camera unless you're using shift/tilt/bellows)
Moving to a tighter aperture should also help. Most lenses don't shoot their best wide open. 5.6 - 8 somewhere is probably that lens' sweet spot where you'll get the best portrait out of it

Irishphotodesk · 09-10-2020 8:48pm

The Darkroom wrote: »

Thanks guys. Am I better off using 4.0 to get used to it first? Is the 2.8 too large an aperture to be getting sharp portraits with?

With the 70-200mm f2.8 mkII, I find with portraits it’s best to shoot f6.3/7.1 or even f8 and adjust your shutter speed accordingly, also when doing portraits, try to experiment with off camera flash.

Essentially, play with the camera/lens combo in different light situations to get a better feel for how they react together.

And ..... enjoy the lens, it’s a fantastic piece of kit , try shooting at different focal lengths, 70mm , 100mm 150mm and 200mm.

Adrian.Sadlier · 10-10-2020 12:23am

With a narrow depth of field, as yielded with any f/2.8 lens at this aperture and distance, I would suggest the following, irrespective of make of camera or lens.

Centre the focus point on the eye, 1/2 way compress the shutter release button so it focuses but does not fire. Then recompose and press the shutter the rest of the way.

This should result in the subject being captured with the eye in focus. Judge the result and adjust aperture accordingly. As staed above, the depth of field at f/2.8 is quite limited, but is usually enough.

To me, it sounds like you are letting the focus to drift to another part of the image.

Oscar Madison · 10-10-2020 8:46am

You must have it on either AI servo and if you have you should change it to one shot.

Myksyk · 10-10-2020 9:07am

All good advice above. At 1600 shutter you're obviously shooting outside and to be fair it is nice to have that shallow DOF when you have busy backgrounds. However, as you have found out, shooting at 2.8 really increases your chances of not getting a sharp focus on the eyes. If the background is to be blurred make sure it is a good distance from the subject and shoot at a narrower aperture to ensure you're getting the whole subject in focus (e.g. f/5.6 - f/8). Otherwise use a plain background like a wall that doesn't need blurring. If you are shooting outdoors avoid harsh, contrasty bright light and look for days or areas where you have nice diffused light (like bright but cloudy days) which will minimise harsh shadows.

If you're shooting indoors with off camera flash then the situation is much more within your control, but you may not have that equipment yet if you're new to portraiture.

CelticRambler · 10-10-2020 11:50am

Adrian.Sadlier wrote: »

Centre the focus point on the eye, 1/2 way compress the shutter release button so it focuses but does not fire. Then recompose and press the shutter the rest of the way.

I'm still a little puzzled by need to recompose, as highlighted by DaireQuinlan's response. This technique (hold and recompose) was great for last-century cameras with a single focus point, but the 5D MkII has nine focus points, and it's strange that the OP has to move the camera so much to get the "whole body" into the frame that the top-most focus point is now well off the focal plane. In portrait orientation, for a whole-body picture, the top focus point is going to be pretty close to eye level without reframing.

I'd nearly be wondering if the problem is more to do with the OP's way of holding the camera (assuming it's not on a tripod) while recomposing, perhaps tilting forwards, or twisting slightly as they bend down? Or could it be that in adjusting the angle of the camera, with the lens cupped in one hand, they're ever-so-slightly adjusting the zoom?

Adrian.Sadlier · 10-10-2020 5:52pm

CelticRambler wrote: »

I'm still a little puzzled by need to recompose, as highlighted by DaireQuinlan's response. This technique (hold and recompose) was great for last-century cameras with a single focus point, but the 5D MkII has nine focus points, and it's strange that the OP has to move the camera so much to get the "whole body" into the frame that the top-most focus point is now well off the focal plane. In portrait orientation, for a whole-body picture, the top focus point is going to be pretty close to eye level without reframing.

I'd nearly be wondering if the problem is more to do with the OP's way of holding the camera (assuming it's not on a tripod) while recomposing, perhaps tilting forwards, or twisting slightly as they bend down? Or could it be that in adjusting the angle of the camera, with the lens cupped in one hand, they're ever-so-slightly adjusting the zoom?

Hold and recompose is suggested because it eliminates a myriad of other potential issues that a beginner may not yet be familiar with on their camera. For all we know, the "recompose" stage could include a partial step back or bending/straightening of the photographers back. Or a change in the focal plane is subject and camera are very close. With a narrow depth of field you need to be spot on!

CelticRambler · 10-10-2020 11:39pm

Adrian.Sadlier wrote: »

Hold and recompose is suggested because it eliminates a myriad of other potential issues that a beginner may not yet be familiar with on their camera.

Yes, I understand the sentiment; but equally, that's the reason for having eccentric focal points - to allow for composition first and then have the camera focus on the critical element without having to move it (very much). I read the enquiry as indicating that the OP is new to portrait photography, but knows how to handle the camera.

CelticRambler · 10-10-2020 11:47pm

Adrian.Sadlier wrote: »

Hold and recompose is suggested because it eliminates a myriad of other potential issues that a beginner may not yet be familiar with on their camera.

Yes, I understand the sentiment; but equally, that's the reason for having eccentric focal points - to allow for composition first and then have the camera focus on the critical element without having to move it (very much). I read the enquiry as indicating that the OP is new to portrait photography, but knows how to handle the camera.

Adrian.Sadlier · 11-10-2020 1:18am

CelticRambler wrote: »

Yes, I understand the sentiment; but equally, that's the reason for having eccentric focal points - to allow for composition first and then have the camera focus on the critical element without having to move it (very much). I read the enquiry as indicating that the OP is new to portrait photography, but knows how to handle the camera.

I guess until we hear from the OP we will never know

Splinters · 19-10-2020 9:51am

You may be better off shooting at f4 or manually focusing at f2.8. The 5D mkII is still a fine camaera, capable of some very nice images, but its notorious for having an unreliable autofocus system. That was probably the single biggest gripe people had with that camera, and biggest issue they fixed with the mkIII. Thats not to say its not a great camera, but every piece of gear has limitations, you just have to find ways around them.

Adrian.Sadlier · 19-10-2020 2:26pm

CelticRambler wrote: »

Yes, I understand the sentiment; but equally, that's the reason for having eccentric focal points - to allow for composition first and then have the camera focus on the critical element without having to move it (very much). I read the enquiry as indicating that the OP is new to portrait photography, but knows how to handle the camera.

Having been involved with many beginners through DCC, one of the most common problems encountered is not knowing how to change focus point settings on cameras. Focus and recompose is a much simpler explanation than going into the focus mode issue on any given camera and works for nearly all cameras.

Focusing with 2.8 at 200m for portrait

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