Re: Focus Point

[Terry's]

I have a Canon 50D

The general opinion on focusing on a model seems to be focus on the eyes.

When focusing is the best way to use the auto focus where it covers all points (the diamond layout of lights in the viewer) or to select the single centre point in the centre to focus with, or should I focus manually?

I hope I have explained what I mean clearly enough to give you an idea of what I am trying to find out.

Regards

Terry

[Mark_Cohran]

My technique is to select the specific focus point closest to the eyes once I'm composed the shot, shift the camera so that point is on the eye, focus, then do a slight recompositon.

If you allow the camera to choose the focus point, you cede control to the camera and the eyes may not be the point of focus that the camera chooses.

If you choose the center AF point and recompose, then with shallow depth of field, when you recompose the plane of focus may shift enough such that the eyes won't be the sharpest part of the image. It's not as critical with smaller apertures, but for portraiture you're generally going to want to use larger apertures and shallower depth of field.

[Terry's]

Hello Mark

Thanks for taking the time to answer my post.

I think I undersatnd what you mean, I will give it a try.

Regards

Terry

[Mark_Cohran]

Good luck. Let me know how it works for you.

[Hedley]

I do try to favour the centre focus point more than the peripheral ones though... is it not more sensitive or is that a myth?

[charlieharper]

Hi Mark,

I'm not sure that I understand what you are saying.................

As an example, lets assume my 40D had just 5 focus points and the models eye was at point "x", just to the right of the R focus point .....

...................T
...........L......C.........R...x
...................B

I set my camera with just the (C) focus point active, put the (C) over the models eye, half-press, recompose and click.... If you choose the center AF point and recompose, then with shallow depth of field, when you recompose the plane of focus may shift enough such that the eyes won't be the sharpest part of the image...
Surely the auto-focus measures the distance from the camera to the models eye just the same using any (single) focus point, so I don't understand how it matters which one you use ??

I understand that in the case above, you would manually select the (R) focus point, but then if your model tips her head so her (near) eye is now on the other side of your viewfinder, do you then select the (L) focus point ? I guess I am asking are you continually changing focus points as you shoot ?

I tried that and found it awkward, that is why I now use the (C) point and recompose.

Should I persevere and get used to changing focus points ?

Many thanks,

CH

[Mark_Cohran]

Hi Mark,

I'm not sure that I understand what you are saying.................

As an example, lets assume my 40D had just 5 focus points and the models eye was at point "x", just to the right of the R focus point .....

...................T
...........L......C.........R...x
...................B

I set my camera with just the (C) focus point active, put the (C) over the models eye, half-press, recompose and click.
Surely the auto-focus measures the distance from the camera to the models eye just the same using any (single) focus point, so I don't understand how it matters which one you use ??

I understand that in the case above, you would manually select the (R) focus point, but then if your model tips her head so her (near) eye is now on the other side of your viewfinder, do you then select the (L) focus point ? I guess I am asking are you continually changing focus points as you shoot ?

I tried that and found it awkward, that is why I now use the (C) point and recompose.

Should I persevere and get used to changing focus points ?

Many thanks,

CH

See this:

http://www.outbackphoto.com/workshop/phototechnique/essay06/essay.html

Yes, I constantly change focus points to pick the one that's going to be closest to my intended point of focus for the given composition.

No one said photography was going to be easy. :)

[charlieharper]

See this:

http://www.outbackphoto.com/workshop/phototechnique/essay06/essay.html
Thanks Mark, It's just simple trigonometry really then !!

That makes sense when it's explained like that bw!!!

Yes, I constantly change focus points.....No one said photography was going to be easy. :)
Oh well, No matter, Something else I've learnt, something else to practice, practice, practice.........rinse, repeat !!

If it was easy, it wouldn't be challenging, and if it wasn't challenging it wouldn't be fun !!!

Thanks again for the heads-up,

CH

[hkhorn10]

See this:

http://www.outbackphoto.com/workshop/phototechnique/essay06/essay.html

Yes, I constantly change focus points to pick the one that's going to be closest to my intended point of focus for the given composition.

No one said photography was going to be easy. :)

Good article post.

Here's an example I use to show the same effect. In this case, I focused on the second white book from the top. The whole "plane" is in focus as opposed to one "point". Taken with the 135L at F2.

http://i253.photobucket.com/albums/hh50/wneder/IMG_01141.jpg

[Terry's]

Not been on for a while, glad to find I am not the only one who was unsure of the best way of focusing.