Need help with consistent sharpness.

01/14/2009 05:17:00 PM · #1

Hi - subject pretty much says it. I need help getting my cannon xsi with a 50mm f/1.4 to take shots with sharp eyes consistently. Sometimes it does and sometimes it doesnt . I set the focus point on my camera to be the middle red dot in the viewfinder... I have good exposure... Usually around sunset... I hold the shutter release down halfway with the red dot on over her eye then keep holding it down, recompose real quick, and take it.
I have more pics on my myspace www.myspace.com/claytaylorphotography where you can see what i mean a little better. Any help is appreciated!

Sony 24-70mm F4 Vario-Tessar T* FE OSS

01/14/2009 05:18:08 PM · #2

And lens is on autofocus

Bear_Music

Samsung Galaxy S24 Ultra

01/14/2009 05:20:27 PM · #3

At what aperture? The DOF at f/1.4 is razor-tin, and if you look at the angles involved you can see that focusing/recomposing actually can move the eyes a significant distance away from being in focus... Depends on camera angle, how close you are to model, and so forth.

R.

Canon EF 28-135mm f/3.5-5.6 IS USM

01/14/2009 06:26:01 PM · #4

Using f/1.4. Usually just a few feet away - fitting their shohlders up in the shot.

TCGuru

Canon EOS-40D

01/14/2009 06:30:40 PM · #5

That's where your problem is. 1.4 is very very VERY shallow DOF. With the technique you are describing, you have a plane of focus somewhere and it's locked, but not on her eyes. General rule of thumb for shooting at f1.4 is focus where you want the focus to be. Don't move the camera after (especially in a portrait). BTW, that lens is sharpest at 3.5. :) Hope this helps.

ETA:

1.4:

3.5:

Message edited by author 2009-01-14 18:32:11.

Foolish Ice

Canon EOS-350D Rebel XT

Tamron SP AF 28-75mm f/2.8 XR Di for Canon

01/14/2009 06:33:35 PM · #6

50mm shot at F1.4 from a distance of 4 feet will give a depth of field of 0.1 feet (1.2 inches), so like Bear_Music said that isn't very much of the subject in focus. At 2 feet away the DOF will be 1/4 inch.

//dofmaster.com/dofjs.html

chromeydome

Nikon D7000

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

01/14/2009 06:40:59 PM · #7

yes--1.4 will give you very shallow dof, so it can be used for great bokeh effect, and for isolating a subject from the background. But it can sneak up and bite you, too. Stop down some and check the result. Your lens likely has markings to let you see the dof: once you focus on your subject, you can get an idea if your dof is 1 foot or several feet (it varies as you focus farther away).

Finding the dof preview button on your camera is worth doing, too. It is your friend when working with wider apertures.

If you re-try some of the same shots with f4, f5.6, f8, etc, you should see a lot of difference.

If you have time, set up with a tripod for a fairly close subject, and shoot it at several or all of the aperture settings, do the same for a medium distance subject, and again for farther distant subject. If you inspect the images, you will get an idea of the sensitivity.