20d Focus test [help]

[kawter2]

ok for all of those who have performed a focus test, can you let me know if I am being anal retentive on this one? i get this result consistantly after several recomposings etc...



50mm @ 1.8
http://kawter.hostrocket.com/focus-test.jpg

is this acceptable

[kawter2]

here is another that seems to have the same trend at f4.0

http://kawter.hostrocket.com/focus-test_f4.jpg

[robertwgross]

Since we don't know anything at all of how this focus test was set up, it's hard to say much. Sometimes details are helpful.

---Bob Gross---

[Nic]

What lens did you use?????

[cc10d]

As they say, it is hard to comment without knowing more, But It seems like you have a normal good focus pattern. The Depth of field is shallower closer to the camera than it is going away from the focus point. (assuming the right side of the pic is the area closest to the camera) I believe that is the normal way depth of field works. So I would think that your test verified good performance. What do you think?

chuck

[kawter2]

http://www.photo.net/learn/focustest/
this is the focus test

basically i set up the image at a 45deg andle and focused on the center bar several times



the lens is a 50mm 1.8 mkII


and yes the right is closer to the camera


THANKS for all the input so far

[kawter2]

As they say, it is hard to comment without knowing more, But It seems like you have a normal good focus pattern. The Depth of field is shallower closer to the camera than it is going away from the focus point. (assuming the right side of the pic is the area closest to the camera) I believe that is the normal way depth of field works. So I would think that your test verified good performance. What do you think?

chuck


that is what i have always thought.. but this site was saying otherwise.. humm i think they might be wrong

this would go along with my shots wouldnt it?
http://www.dofmaster.com/files/dof.gif

[robertwgross]

Yes, you get a third of the Depth of Field in front of the perfect focus plane, and you get two thirds of it behind the perfect focus plane.

When you do a focus test like that, you want to make sure that the focus plane and everything of interest is farther than the minimum focus distance for that lens. We don't know that for a fact since it was not stated.

---Bob Gross---

[kawter2]

Yes, you get a third of the Depth of Field in front of the perfect focus plane, and you get two thirds of it behind the perfect focus plane.

When you do a focus test like that, you want to make sure that the focus plane and everything of interest is farther than the minimum focus distance for that lens. We don't know that for a fact since it was not stated.

---Bob Gross---


we'll time for me to feel stupid!!! I will have to do this again and make sure that the subjest to the right is in the min focus plane. but i am slowly convincing myself that my camera is ok

[samdring]

Is it not a fact that most people here would now say that focus tests can only be done with a rule inscribed with Roman numerals?

[MarkH]

we'll time for me to feel stupid!!! I will have to do this again and make sure that the subjest to the right is in the min focus plane. but i am slowly convincing myself that my camera is ok

Your camera is fine, it focuses OK!

Now go out and find interesting subjects to take photos of.