Help getting shallow DOF

I been shooting with a Canon 60D and a Sigma 17-70mm F2.8. I was shooting Saturday and my settings were 17mm @2.8 200 with octobox and a canon flash. My background was blurred but not as much as I like. What am I doing wrong? I hate trying to blur in Photoshop I want it right in the camera.

Only one option.. get closer. You can blur the background, by having more distance between subject and background.

Rules of thumb, the wider the focal length, the deeper the depth of field. The farther you are from the subject the deeper the depth of field. So if you want blur dont use a wide angle lens. Run some scenarios using the depth of field calculator at dofmaster.com to see the effect of focal length on DOF.

shoot at 70 instead of 17. you'll never get much separation at wide angles. if you want a wide look with lots of separation then you can look up the brenizer method. the shallowest you can go at that focal length in camera would be with a full frame camera with the 24mm 1.4. or on film with an 8x10 camera

Help is right here:
http://www.dofmaster.c​om/dofjs.html

At 17mm, no matter your aperture, you're just not going to get a huge amount of BG blur.....certainly not enough to totally obscure the BG. To create better BG blur, you have several options. First, use the longest focal length possible. Second, put as much space between your subject and BG as possible. Third, shoot as close to your subject as you possibly can with your longest FL lens.

Buy a fast prime. /ProblemSolved

Tony_Stark wrote in post #17172355
Buy a fast prime. /ProblemSolved

Would she have to put it on the camera or is just owning it sufficient?

Tony_Stark wrote in post #17172355
Buy a fast prime. /ProblemSolved

Not if its a wide one!

Like others have said, use the 70mm end of your zoom, shoot it wide open, get close to the subject, keep the background far if possible.

mdaddyrabbit wrote in post #17172221
I been shooting with a Canon 60D and a Sigma 17-70mm F2.8. I was shooting Saturday and my settings were 17mm @2.8 200 with octobox and a canon flash. My background was blurred but not as much as I like. What am I doing wrong? I hate trying to blur in Photoshop I want it right in the camera.

like others have said, if you want it "right in the camera" you need to shoot longer or larger

Shallow DOF and blurred backgrounds are related, but they are not the same thing.

For example, if you shoot with the same subject framing and aperture using different focal lengths, then the DOF will be the same but the background blur will be different. Perhaps an example description with some pictures:

First shot is 50mm, f/1.2. The second shot is from four times further away, 200mm and f/2.8. Aside from the perspective difference, the key observations here are that the second shot has both more DOF and more blur.

So if you want more blur, you need to shoot from further back using a longer lens.

If you want less DOF, you need a faster maximum aperture at whatever focal length you use.

I once saw a diagram here on POTN which was very helpful in showing the relationship between DOF and focal length, camera to subject distance and subject to background distance. It showed 3 cameras which were each aimed at subjects with these things varied. I've never been able to find it since. Does anyone know the one I mean?

Someone has recently posted about a DoF/Bokay simulator on POTN. The screen shots look good. I'm sure forum search would find it.

Alan

BigAl007 wrote in post #17172727
Someone has recently posted about a DoF/Bokay simulator on POTN. The screen shots look good. I'm sure forum search would find it.

Alan

Here