A Little Help W/ Aperture and Depth of Field

rickabobaloey · Jun 21, 2010

So I'm indoors today. Playing w/ my camera in AV mode. I'm trying to do a very simple thing. Well, at least it sounds like it should be simple. I'm trying to create depth of field between a book I have open on my desk, and several behind it. I'd like the first book to be sharp, and clear, and the ones behind it to be a little out of focus. I've used apertures from the lowest (wide open) top the smallest available and still can't seem to get the affect I want.

Are the books standing up too close?

Robin Usagani · Jun 21, 2010

all you havve is the kit lens which is a very slow lens. You need to focus to the book at the front, not the back. You should see the back is blurred if you do that but wont be as blurred as you think. You have to put the book farther apart. If you have a fast lens on the other hand, you can blur it out pretty good because you can have a very shallow DOF.

Robin Usagani · Jun 21, 2010

What you do is, point it at the book at the front half way to auto focus, then keep it pressed half way move it to the way you have it now then take the picture. By doing that you will focus to the book at the bottom.

Big Mike · Jun 21, 2010

What you are trying to do is create a 'shallow' DOF.

The DOF is a result of the aperture, the focal length, the distance to the subject and the size of the recording medium. And some of those factors are working against you. For example, (as mentioned) your lens's maximum aperture is only F3.5 to F5.6 (depending on the zoom)...which isn't considered to be very big. It would be much easier if you had a lens with a maximum aperture of F1.8 or F1.4 etc.
Also, your camera has an APS-C sized sensor. It's much bigger than one found in a point & shoot digi-cam, but it's still smaller than a frame of 35mm film or a 'full frame' digital SLR.

What you can do, is use your largest aperture (smallest F number). Then try to zoom out as much as you can, while at the same time, getting as close to the book as possible. It's obviously a trade off so play with it. The real trick will be moving the front subject farther away from the background subject. The more you can separate them, the blurrier you can make the background.
Of course, buying a 'faster' lens would also help a lot. (50mm F1.8 is a nice cheap lens that's I'd suggest).

j-digg · Jun 21, 2010

General rule of thumb on TPF... Always listen to Mike ^ :lol:

Here are some decent links on the subject:

Understanding Depth of Field in Photography

http://www.mir.com.my/rb/photography/fototech/htmls/depth.html

DaevidClarke · Jun 21, 2010

^^second

Petraio Prime · Jun 21, 2010

You can't always get what you want.

But if you try sometimes....you just might find...

rickabobaloey · Jun 21, 2010

Thanks Schwettylens, and Big Mike!

I understand that the kit lens has limitations, as well as the camera that I went w/ as my first. I just need to learn what those limitations mean and how they'll correspond to photos I'd like to take.

I can slide the front book maybe another 2-3 inches away from the books behind it, but not much more than that.

Even if I don't get the shot I was looking for, it's still a learning experience and I'm enjoying it.

That lens looks nice. Just googled it quickly and read a little nice review, and I see that it is less than $100. That's pretty awesome. I take it that it is what I see referred to as a "macro" lens, because it has a larger aperture?

And thanks for the links J-Digg, going to check them out here in a moment.