Help please! dof/new camera issues

[afrikaner07]

Hey Everyone,
I just got my new Rebel XSI and a 50mm F/1.8 Canon lens. I thought that when i got it out of the box that its gonna take awesome shots. I must be doing something wrong. Even when I am on Auto AF selection, it rarely focuses on what I want, so I switched to manual and made the center point what I use to focus. Problem is, even when I focus on the eyes, the people are still out of focus!...this is rather frustrating. I used a tripod to stead the shots and a 2 second timer so my hand doesn't move it ever so slightly. I use low ISO (100), and shot with F/1.8. Is the depth of field so shallow that the rest of the face is out of focus? I know this has been beaten to death, and I would have gone looking for the thread, but I didn't have the time to really search...although in the time it took me to type this I probably could have found it. As always, your help is REALLY appreciated.
Cheers,
Johan

[Graydon]

an F1.8 lens has a pretty "shallow" dof.... from what I've heard (no experience personally)...

but posting an example would really make it easier to let you know.

[110240]

my 1.8 lens is just groovy for portraits baby!!!

[Jenny Z]

1.8 is fine, as long as the subject isn't close to your lens. The farther out the subject is, the deeper the dof.

[afrikaner07]

then if aperture is fine, why isn't my camera focusing where I tell it to? every time, I am pointing right at the eye of the of the subject, boo

[Wes]

I don't know anything about Canon gear but I know that on my Nikon's I'm able to choose the focal point that I want to use in the viewfinder. Put your focusing reticle on the object that you want to focus on, lock the image (on Nikon this requires pressing the AF-ON button, or pressing the shutter release ½ way), and then recompose the image.

As Jennifer says above, if you're shooting at f/1.8 make sure that you back up a bit in order to get a deeper DOF.

[afrikaner07]

Thanks everyone. I do use the manual AF selection, which means I use the center of 9 AF points. I focused on the eyes, then recomposed the photo. I am just starting to wonder if it is me, or if I got a defective camera (I'd prefer the odds to be in the direction of me being semi defective with the new camera in hand).

[bondarnes]

First select and use the focus point nearest the eye. Focusing and recomposing can put the focus off slightly. Second use a cable release, some other remote release or the camera shutter release gently. Between the time you focus....recompose.....set timer.....wait two seconds.......then fire your subject may have moved slightly. I use a wireless release that I bought from Arlington camera.

[guitarbug]

I bet if you open up to at least 3.5 , you will not have this problem. I agree with the others thats its the dof ! Have you tried this ?

[venchka]

Welcome to the club.

Revelation #1: Don't blame the hardware. It's only doing what you tell it to do. You'll figure things out sooner or later. When in doubt, read the book. Most 50mm lenses are quite manageable from f=2.8 to f=8.0.

[Dobick]

at 2 seconds with a living subject -- it may be that the image is not out of focus, but moving.
There are a lot of ways to tackle this, but shooting that slow is likely to produce motion blur in the subject.

[venchka]

2 second self-timer dealy is good. However, did your subject move during those 2 seconds? Move out of focus that is.

50mm/1.8 lenses have a fairly shallow depth of field. More shallow than a 35/2.0. Not as shallow as an 85/2.0 or a 135/2.0.

As focal length increases, DOF decreases.
As aperture number increases (example: 2.0 to 5.6), DOF increases.
As lens to subject distance decreases, DOF decreases.

All of this used to be a lot easier to grasp when you real aperture rings and DOF scales engraved right on the lens.

[rbalcom]

Originally Posted by afrikaner07

Is the depth of field so shallow that the rest of the face is out of focus?

The answer is probably yes. A key missing piece of information is how far you are away from your subject. Assuming the XSI is a 1.6 crop factor like most of the non-1D Canons, I would guess that you are about 6 feet away. At that distance, your DOF is about 3.3 inches. Assuming that you focused on the near eye, that would give you about 1 inch in front of the eye and 2 inches behind the eye in focus. Move closer to 4 feet and the DOF drops to about 1.5 inches, or a half inch in front of the eye and an inch behind the eye in focus.

Also, at those shallow DOFs if you are using the center AF point and the recomposing, the focal plane shift during the recompose could easily even throw the eye out of sharp focus.

[afrikaner07]

thanks you guys. your help was incredible. I came to the same conclusion as you all. I shot the same person's sister yesterday (with the camera) and increased the aperture, which had much better results. I did not use a timer, since it made me miss those reaction shots. I also stood further away, which like you had mentioned did increase the depth of the depth of field. All in all, a valuable lesson. Thank you again for all your help!

Summary:
I decreased the aperture to make it have a deeper depth of field and I also stood back a little further. I also used poses that were easy to keep steady (so no balancing on one hand while trying to levitate rocks with the force type of thing). I also sharpened the crap out of the photos, lol. Here are three of the results.







For my first portrait photo shoot...I didn't think they turned out all that bad. I didn't use fill flash (probably apparent) and I had no other way to light the people better. All I had was my lens and my camera and a tripod.

[venchka]

Good progress.

I also sharpened the crap out of the photos, lol.

Rethink that.