Some professional help needed.

[eliza61]

Newbie begging for some help. So I finally made the leap and purchased a dSLR camera. I have the Nikon d3100 which I like and I'm trying to learn how to do more than just point and shoot. Anyway I took a entry photo workshop and I'm having a bit of difficulty and was wondering if you guys could give me some suggestions.

Anyway, I'm learning about Aperature. If I understand this correctly a smaller F stop# will give me less depth of field and blur the background, while a larger F stop # (smaller aperature) will give me sharper images.

problem is I tried it and don't notice any difference.

This is F5.6

This is F36

I don't see any difference. both cases I was focusing on the middle tree.

 

[SrisonS]

In the top picture, the fences way in the back to seem to be a little more in focus than in the bottom pic. Also, depending on various things; like how far the subject is from you, or the spacing of everything else in the picture, you might not notice too much of a difference.

Try standing next to that first tree on the left. Focus on the middle tree at 3.5, then focus on that middle tree at like 8.0 or 11.0. You should be able to see a difference then.

 

[photo_chick]

3 things affect depth of field. Aperture, focal length and distance to subject.

Use an object that's closer to you and it will make it easier to see the difference. And make one object the focus of the image and not a whole scene.

 

[mrodgers]

An example of depth of field. This was taken with a simple superzoom camera at the lowest aperture possible, f/3.5 which is also not comparable to a dSLR f/3.5 because of the physical size (more like an f/8 on a dSLR.)

Note the subject at the sharpest with the smaller "flowers" out of focus and the fence in the back more out of focus. This happened as was said, not only because of the aperture, but also because of the distance relationship between the camera and the subject and the subject and other elements in the frame along with the focal length. Focal length here was at my maximum of 63.3mm, which is approximate equivalent of 200mm on a dSLR (focal length is calculated taking sensor size into concideration.) The camera was fairly close to the subject when I took it.

To maximize the capability of shallow depth of field, you want the following: larger aperture, longer focal length, and short distance from camera to subject compared to the background you want to blur. When you frame a wider scene such as yours (wide angle taking in a lot of area) the depth of field is going to be much larger than if you closed the distance on one subject by moving closer and using a longer focal length.

 

[TXFL]

Maybe this will help

http://www.dofmaster.com/dofjs.html

just enter you camera model number and play with the Focal Lenght, Fstop, and Subject Distance, and this calculator will give you the Total Depth of Field.