Issue with Depth Of field - Canon 60D

aganguly · Mar 9, 2011

Hi,

I bought a new canon eos 60d with 18-200mm canon lens. I am new to DSLR.

I wanted to take pictures with the background as blurry/hazzy and the focussed object as prominent. I understand that this is acheived by depth of field..

Now..I have moved the dial to "Av" mode , and have set the aperture to 3.5.. I am trying this in my room..so have set the ISO to around 600-800. But, whatever I do I am not able to acheive the result..All the objects & background are prominent. I have AF button switched 'ON' on the lens and have tried with AF Quick and AF live as well..

Can you guys help me to solve this issue.

Thanks,
Archan

Jarmo · Mar 9, 2011

Use the longest possible focal length at the closest possible distance. That should give you the best separation from the backround.

aganguly · Mar 9, 2011

@Jarmo : Did you mean that I should zoom my lens ? How to set the longest possible focal length. Also, let me know if there is any control in 60D using which I can set focal lengths. Sorry if this question sounds stupid. Thanks

reznap · Mar 9, 2011

If you're using the lens at 18mm indoors, you're going to have a hard time getting a shallow depth of field.

Hyperfocal Distance and Depth of Field Calculator - DOFMaster

aganguly said:
@Jarmo : Did you mean that I should zoom my lens ? How to set the longest possible focal length. Also, let me know if there is any control in 60D using which I can set focal lengths. Sorry if this question sounds stupid. Thanks

You turn the zoom ring on the lens.. like in a twisting motion. The barrel will extend --- Zooming, by definition is changing your focal length.

Big Mike · Mar 9, 2011

Welcome to the forum.

You are on the right track. You want to use the largest aperture you can (lowest F number)...but you have to realize that your lens is not ideal for this. It would be much easier if you had a lens with a larger maximum aperture...something like F2.8, F1.8, F1.4...and those are usually prime (non-zoom) lenses.

You can still render the background very out of focus, but you have to use more than just the aperture. As mentioned, you can get a shallower DOF by using a longer focal length...as long as you're OK with the tighter/closer composition. But if zooming in causes you to back up, then it's defeating the purpose. That brings us to the other thing you can do, get closer. The closer you are to your subject (point of focus), the more shallow your DOF will be. So if you get as close as you can (check your lenses min. focus distance), then your DOF should be fairly small.

Lastly, if you want the background to be very out of focus...then set up your shot so that the background is a lot farther behind the subject. For example, in your room, the background probably isn't more than 6 feet behind the subject. But if you take it outside, so that your background is much farther away, then you can get it to be much more out of focus.

But if this is something you really want to do...then go buy a 'fast' lens. The 50mm F1.8 is around $100.

aganguly · Mar 9, 2011

Thanks All..I will try to zoom in and see if I can get a better result..As suggested by Big Mike I have ordered a 50mm 1.8 lens.

Let me know if there is any difference if I choose AF live and AF quick.. I see that there is 9 points in AF quick..I tried to have manual selection and selected just one point. The far right point. Now, when I half press the shutter button, I see that it gets green..But there is a large rectangle as well..That does not get green.. I am a bit confused ..what is for what ?

Big Mike · Mar 9, 2011

Read through your manual for info about focus points & modes etc...as your camera will be different than many others. But in the end, you can only be focused on one thing (one distance)...all the points & modes are just different ways of getting there.