Focus for Full Length Shots

[chimera_h]

I'm having problem with focus for my 3/4 and full length shots. I had this

problem with my previous camera and a couple of lenses, so I know it's me, not

the camera. My close up shots are fine.

 

I have a Canon 30D and mostly use my 28-75mm (I think) and 85mm lens. I use AF,

shoot in manual, and always keep my shutter to 140 and faster and I use one AF

point at a time (which I select). I always focus on one eye, but sometimes the

focus will fall toward the bottom of the image or somewhere near the face.

 

Shouldn't I be able to shoot at any aperture and get a clear image? I realize

shooting at 1.8 takes skill (not sure what kind, but that's what I've heard),

but shouldn't I be able to shoot at f/4 on an 85mm 2.8 lens and get a clear full

length shot?

 

Maybe I don't understand the focal plane and if you send me to one of those

overly-technical photo sites to explain it, I'll get lost.

 

Do I have to be on the exact same level as the subject when taking a shot? If

they are sitting, could I stand and still get a sharp image?

 

 

Lastly, how clear should the eyes be for a full length shot? Maybe I'm expecting

too much. But I still do have the question as to why, during a 3/4 length, the

focus sometimes falls just next to the face.

 

Thanks

[bryantan]

Examples?

[stillbound]

the issue seems to be you are not focusing on the eyes. If that is what you want in focus then that is what your focus point should be. I know that sounds overly simple but select a single focus point. Lock the focus and recompose so that the eyes are sharpest. F4 is going to produce a bit of bokeh (the out of focus look) so you may want to start exploring 5.6 or even higher depending on the look you are looking for. In my own work i want a shallow depth of field 80% of the time and 90% of the time I just focus on the eyes and then compose knowing that a good portion of the image won't be in true focus but that is often what I am looking for...

 

JC

 

[sig removed]

[link]

Paige,

 

I'll assume you're not imagining this. What can you do?

 

1. Use a shorter shutter speed. 1/140sec might show camera shake a bit. Use 1/250 or

higher when possible. When you're zooming into your photos, don't let camera shake fool

you into thinking you have a focus problem.

 

2. Use the center focus position only and re-frame rather than use the outer focus points. I

don't know about your camera, but my 5D gets the most focus info on the center position.

 

3. It's possible that while your camera focuses with a wide open iris, the focus shifts

slightly when it's stopped down to shoot the picture. Don't know what to do about this

except to send the lens in for repair.

 

4. When shooting wide open, #3 shouldn't happen, so you might have a camera problem

if you still focus on the wrong spot. Try manual focus. If the problem persists with manual

focus then you have a camera problem that needs repair.

 

All in all the camera should focus on the auto focus position selected, period. The center

position should be the most accurate though. Auto focus is not perfect though and if you

or your subject is moving, even just a little, you can throw the focus off. Also there must

be some detail (contrasting) on the auto focus position or it will get confused. Try focusing

on the clear blue sky and see what happens...

[mark u]

Do not follow b g's advice: focus/recompose sucks:

 

http://visual-vacations.com/Photography/focus-recompose_sucks.htm

[john_bellenis]

This is a common situation caused EXACTLY by using a wide aperture, using an AF

point to pre focus on the eyes, recomposing and unintentionally then sending the

focus point behind the subject.

 

Along with the frequently appalling self aggrandizing and posturing by

"professionals," plain wrong advice is one of the downsides of a public forum. As

Mark U says, focus / recomposing (in this kind of situation) sucks, and it only

"works" for people when they have set a small enough aperture to compensate for

the focus error.

[davebell]

I very often focus and recompose without any issue at all. I fully understand Mark U's link and agree that under certain conditions it is dodgy - i.e. close to subject, high focal length and wide aperture. But for a 3/4 or full length shot with an 85mm lens or less, at F5.6 the DOF should be fine. At least that is my experience. That said, I am trying to get used to flicking the selected focus point around very quickly so as to minimise the effects of focus-recompose.

[peter_mckone]

Some people suggest that full-length photos should be taken with the camera at waist level, rather than at eye level. At eye level, it would be hard to focus on the face and still have the subject's legs in focus. Of course you get sharper results if you set the camera on a sturdy base. If not a tripod, then at least a table.

[chimera_h]

Peter, I've heard about shooting from waist level.

 

I guess I'm wondering if there is something about the focal plane that I'm missing. Someone once said it is like a sheet of glass and everything right on the glass should be in focus and everything in front of and behind will be out of focus. Does is matter how I stand or how I angle the camera.

 

I NEVER focus and recompose, so I'm just about always using the outer focal points. Does the focal point have to be on the eye if I want the eyes in focus, or if I follow the plate of glass idea, should I be able to focus on let's say even the chest and the eyes would be in focus. Hope this makes sense.

 

I'll post two examples, but they're probably not large enough for you to see.<div></div>

[chimera_h]

Sorry, but I don't know how to make that large enough to tell. I'll try again.

[chimera_h]

One more time...

[chimera_h]

Another example....<div></div>

[link]

Paige,

 

On the examples that you've shown, prefocusing in the center and reframing should

have no real effect on the eye focus as the eyes and the center of frame will be

close enough to each other in distance.

 

Your examples are too small to see if the eyes are out of focus, compared to the

leaves on the right, for example. If the camera is focusing too close, ie.something

like 1-2 feet too close than you may have a technical issue with either the lens or

camera. But I can not tell from your examples.

 

I will say this though: at 60mm a 1/125 sec shutter speed is too long for a critically

sharp hand held shot unless you're using an IS lens.

[link]

And about the waist level approach. Diane Arbus was not selling beauty shots to

paying clients, and this approach worked for her, though I think it was really because

she used cameras with a waist level finder and not an eye level finder.

 

Do you really want to look up the nose of your paying clients? Probably not in most

cases.

[beauh44]

Another take on focus/recompose by our very own Bob Atkins: http://www.bobatkins.com/photography/technical/focus_recompose.html

 

Dr. Bob sez: "With longer lenses used further from the subject the effect would be

even less. So I think it's pretty safe to say that focusing and recomposing, even

though it theoretically can result in being slightly off focus, works pretty well in

practice and it's not something you really need to worry about 99% of the time."

 

But having pointed that out, I try *not* to use Focus/Recompose myself, particularly

if I want the eyes in focus and I'm shooting wide-open with a fast lens and the DOF

is so unforgiving.

 

However, you're not shooting, typically, using a very narrow DOF and you're

shooting from pretty far away, so it might be a useful thing to at least try. It's

possible, I suppose, that something could need calibrating and I've read that some

of Canon's, peripheral, DSLR autofocus points may actually be a little off from what

you see in the viewfinder. In other words you may be focusing slightly behind or in

front of the eye even though it appears you're dead on it. If that's the case, trying

focus/recompose might help because the center one is usually pretty accurate.

 

You could put your camera on a tripod and test its peripheral AF points to see if

they're a little off; that way you could either compensate yourself if it's predictable,

or have Canon adjust your camera.

[peter_mckone]

In the view finder, you can see several little crosses that represent candidate focus points. When you press the shutter button half way, at least one cross lights up. This shows the distance that the camera has chosen to focus at. I think the camera focuses at the nearest object that coincides with one of these points. Try to get one of these crosses on the subject's eye, and make sure that one lights up when you press the button.

 

As an experiment, try the auto depth of field setting on your dial. The camera will try to increase the focal ratio so ALL the points are in focus. Of course the shutter may stay open longer than you can tolerate.

 

Some of the focus points need a vertical straight line to function. Others need a horizontal line. The center point works with either. Someone posted research on the Web showing the orientation of each focus point.

[chrisjb]

I hope I don`t repeat something said, Understanding how the focus works helps. In order to AF the camera needs a contrast line, light and dark. an example is a dark eyebrow. if you FP is covering a plain skin tone it will struggle. even pale blue eyes on fair skin can be trouble some and manual focus needed, The center FP is the most accurate in your camera as a cross point. Focus and recompose is fine so long as you allow DOF to cover the change if focussing towards the edge of the frame. I`ve always kept the lens slightly higher than a subject. The look up a persons nose from WLF is very unflattering IMO.

 

Most of our work is flash so rarely above 1/90th sec, the 85mm has not got a very close focus range about 4 feet I think, something to be carefull with. also quite often the FP may not be perfectly aligned, but you mention this is an on goind problem. I`d suggest practice some focus recompose shots at f8 and gradually open the lens till you feel its right for you. As well as placing any focus point over the most contrasty area in a frme to lock focus.

 

If you have a pro nearby, approach them and ask for assistance, if they have time they should be able to give pointers.

 

Good luck {)

[michael.gregory]

Dear Paige,

If you find that using autofocus is causing a problem, there is always the option of

turning it off. Focus, use dof preview, and use a tripod. I realize this can be difficult in

some lighting conditions.

[mark_audacity_romberg]

Paige, something that helped me a lot when I was learning was to visualize the plane

of focus as something attached to my camera, radiating from the lens.

 

I don't know if you are a spatial/visual thinker, but I always try to imagine it as a plane,

like a big sheet of plywood, that I'm attempting to place in space such that it transects

all the important bits of my subject.

[William Michael]

It is difficult to accurately establish the Plane of Focus in the first two images because of their (uploaded) quality

 

On the third image (Half Shot aqua Dress and Leaves to Camera Right) the plane of focus is in front of the subject: it is through the leaves to Camera Right.

 

The DoF just touches the Subject`s right Breast, but the eyes and face are not in acceptable focus.

 

Although I could not access the EXIF data, it appears to me (from the amount of compression) the zoom was set around 60mm to 75mm.

 

That being the case ( and if it is a full frame crop), you would have about 8 or 9 inches DoF to work with, using a 30D.

 

In this shooting scenario (IF I were to use Automatic Focus), I would have used the centre point only and CONFIRMED that focus and then recomposed the shot to suit. I would have focused on the contrasts of the Black (undergarment) Aqua (Dress) and skin tone (top of right Chest) using the centre AF and then CONFIRMED that focus. That last step is most important

 

That is MY method, when using AF: and NOT stated for an argument on the pros and cons of F&R.

 

The point I am wishing to make (to assist) is that to use F&R you must know what you are doing and what the camera is doing and what the latitudes are.

 

I think the most likely cause of your ongoing problem is that you do not understand the nuances of the Canon AF and the system, and most likely even though you think you are focussing on the eye, you are NOT actually focusing on the eyes; or you do focuses on the eye and then the camera focuses on something else before the shot.

 

1. Firstly the AF points extend beyond the red squares.

 

2. Secondly they pick up best on CONTRAST differences.

 

3. Thirdly it is very important to use the system such that it does NOT refocus after you have confirmed focus.

 

In regard to point 3: I suggest yo consider setting C.Fn 4 = 1 and use the `*` to manage focus (exclusively) and use the shutter (exclusively) to take the picture.

 

Please see below FYI, note especially comments by Nadine Ohara and Myself regarding AF generally.

 

Specifically my post (Jun 01, 2008; 12:15 p.m.) gives a shooting protocol you might wish to try.

 

 

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00PdBx

 

Note that you can still use the protocol I set out above and you do not need to recompose the shot if you feel uncomfortable with that procedure.

 

You instead can select one of the other AF points to achieve the plane of focus you wish. But the point is you confirm that focus and have it locked by selecting C.Fn 4 =1

 

WW

 

.

[chimera_h]

Wow! Thank you so much everyone for the explanation. I do use back button focus ( * ) and I read the link to the other post that was similar to this.

 

I guess I want to understand where the focus should be for a 3/4 length and full length shot. I thought a focus point should always be over one eye and if that were the case, the I'd have to use one of the outer AF points, not the center. However, after reading, it looks like I should use the center AF point on the center of the main portion of the image. Correct? So, because there is a whole body involved, the center would be the torso.

 

Next, after confirming focus (by the red light, right?) do I hold the ( * ) button or let it go? Maybe that's where there is a problem? I think I usually hold it down.

 

If the red AF points are not accurate, then how do I know which portion of the area around the AF point?

 

One more thing....isn't my shutter speed supposed to be twice that of the focal length? So, for my 85mm, my shutter should 170 and faster?

 

Thanks. I really appreciate the help.

[mark_audacity_romberg]

Shutter speed is 1/focal length, so for an 85mm lens your minimum shutter speed

should be the closest speed to 85, I think it's 80 in 1/3 stop steps.

 

I would use the outer AF point and focus on the eyes. No use getting her tummy in

focus and not her eyes.

[William Michael]

> I guess I want to understand where the focus should be for a 3/4 length and full length shot. I thought a focus point should always be over one eye [. . .] it looks like I should use the center AF point on the center of the main portion of the image. Correct? So, because there is a whole body involved, the center would be the torso. <

 

No. You need not automatically think that the focus point be the centre of the torso for a FL shot.

 

I think there is confusion: I think we all agree we want the face and the eyes in focus.

 

I think you are confusing the suggestions about how to get to that RESULT.

 

My point was that in this particular scene (NOT a general rule), the eyes, (in fact none of the face) had a CONTRAST difference ENOUGH, nor is large enough to accurately confirm the AF.

 

That is why I would choose the top of the chest, (where the Aqua, Black and Skin Tones meet), because it is in the SAME PLANE as the eyes and face and thus if the top of the chest is in focus so will be the eyes.

 

The subject has a small waist, and it too seems in the same plane as the eyes: and if she had a belt with a contrasting buckle I might have used that point to focus upon.

 

Similarly, in this particular instance I would not have used her hand, because it is too far forward, nor her right breast if she had a contrasting top, because it is too far forward also . . . etc . . .

 

So there is not any one rule where there is a single `spot` to focus upon, for a full length shot.

 

But I was attempting to get the point across about HOW the AF works, and after understanding those issues, I merely described how I would have approached this particular scene: another scene would have been different.

 

Also it is important to realize that you are working at a very small DoF when that lens is at F3.5 and (as I guessed) at about FL = 70mm: so these issues about focus become more critical.

 

To your other questions:

 

If using the `*` button to focus, once attained the AF should stay until the button is released and depressed again, but if you hold it down, you might be momentarily releasing it?

 

In my experience the area the AF sees extends just beyond the area of the red squares.

 

The 1/focal length for the shutter speed is a guide ONLY: you can get visible camera movement at 1/160sec with an 85mm lens on a 30D.

 

(Aside: As for that `rule` or `guide` we would normally FL x1.6 for use on a 30D, which would be about 1/135 for an 85mm lens)

 

 

 

WW