Weird Focus Area

[alemar_calambro]

<p>I have not notice the focus on my camera till I start shooting an object that has a solid background. Is this normal where I am focusing in. The vertical is focus, I thought the object of the area you want focus will be circular. Is this normal or am I thinking of the focus are wrong? This was taken with a Rebel 450d with a 24-105 f/4L</p><div></div>

[Robin Smith]

<p>Quite normal</p>

[alemar_calambro]

<p>Here is another photo</p>

[alemar_calambro]

<p>Here is another photo, taken with a 50mm f/1.8</p><div></div>

[alemar_calambro]

<p>If this is normal, is their a way to fix this or a technique to use? I like my focus area in a circular not in a long line.</p>

[bobatkins]

<p>In a word, no. Focus occurs in a plane. Either everything will be in focus or if there's a region in focus it will be in a line.</p>

[steven_f1]

<blockquote>

<p>If this is normal, is their a way to fix this or a technique to use?</p>

</blockquote>

<p>Near and far objects outside of the depth of field will be out of focus. So if you compose a shot such that objects are out of focus on the edge of the horizontal as well as the vertifcal, only the center will be in focus. Alemar's photo is composed in that way. The focus point is slightly to the right of center. However everything at the edges of the photo is out of focus. </p>

<p>In your photo you had the insect parallel to the sensor so all of it was in the depth of field. As a result the portion of the wall that was parallel to the insect was also in focus. If you had adjusted your position so that only the head was in focus (wings out of focus) while keeping the wall in about the same possition relative to the sensor, everything but the head would have been out of focus. You should be able to see this in the view finder before you snap the photo.</p>

[keith reeder]

<p>Think of the image as a series of slices going from the lens into infinity - your subject will fall within one of those slices, and you control the depth of the slice by adjusting the aperture. </p>

[phule]

<p>[[i like my focus area in a circular not in a long line.]]</p>

<p>Me thinks you've seen one too many photoshoped images.</p>

[alemar_calambro]

<p>Thanks I did not know the focus occurs in a plane. It just seems weird to me that it occurs like that.</p>

[kari v]

<p>Where have you seen "circular" focus area?</p>

[charedan]

<p>Taking a picture of a balloon for example with a shallow depth of field might give you a round focus area, but this as to do more with perspective of the subject rather than photo technique.</p>

[James G. Dainis]

<img src="http://www.geocities.com/dainisjg/Sqre_crcle_norm.jpg"> <img src="http://www.geocities.com/dainisjg/Sqre_circ_dist.jpg"><P>

 

If you shoot the wall at an angle the far side of the circle will be limit of focus since it is further from the lens. If you had shot the wall with the camera facing down, the focus ellipse would have been horizontal not vertical.