Steve's Digicams Forums

Steve's Digicams Forums (
-   Tips & Tricks (
-   -   Canon T1i AutoFocus and People on Different Planes (

CynthiaK Apr 17, 2010 8:51 PM

Canon T1i AutoFocus and People on Different Planes
I have a Canon T1i. My main photo subject is my 5 year old and her friends. Usually candid and I have to be fast. For some reason, I cannot seem to get both kids in focus (using autofocus Al Servo Mode) - especially if one is in front of the other (even slightly) and they are not right next to each other. I get one in focus and the other soft. I have tried center-weighting the focus point, I have tried using all the focus points; I have tried pressing the shutter halfway down and reframing and I still did better with a point and shoot. What am I doing wrong?


Mark1616 Apr 17, 2010 9:36 PM

OK, you are experiencing something very common when someone switches from a P&S to a dSLR and that is encountering depth of field (DOF) for the first time.... well in fact its always been there but usually it hasn't been narrow. With you P&S camera most things are in focus due to it using a small lens.... with a dSLR you have to use a longer lens to get things to look the same and this reduces DOF. Usually this is favorable for shooting portraits etc where you can isolate your subject, but in your case it isn't favorable. It's 4.35am here and I should have been in bed hours ago so I just did a quick google to find a page that seems to have all the relevant information.

If this doesn't answer your questions please post again and I will answer when awake, or probably before that someone else will jump in.

Hope it helps!!!

Mark1616 Apr 17, 2010 9:38 PM

Oh, I deleted your other thread as it's easier to get people looking and answering in one place so they can build on what has already been said.

CynthiaK Apr 18, 2010 7:32 AM

off to read the article.

One other question - would back button focusing help me? If so, I know how to reset the camera in custom functions, but need a walk through of how exactly to use it. Do I still depress the shutter halfway to focus and THEN press the back button and wait for the shot?


JohnG Apr 18, 2010 7:38 AM


Originally Posted by CynthiaK (Post 1081548)
off to read the article.

One other question - would back button focusing help me?

No. Back button focusing will do nothing to increase depth of field. In general it won't help at all for the type of thing you want to do. It can be useful for sports / action shooting but only in certain circumstances. We can discuss it if you wish, but I think you're better off concentrating on learning about depth-of-field right now. Back button focus is a different topic entirely.

VTphotog Apr 18, 2010 2:27 PM

You might be better off using Av mode, setting the aperture to f/8 and, if indoors, use flash.


toshi43 Apr 25, 2010 10:33 AM

Try using smaller (bigger number) aperture values in Av mode combined with a higher ISO, say 200-400. You'll easily find a combination that keeps shutter speeds in a usable range and provides a deeper DOF.The camera's anti-shake or IS system should be on as well. Play around with the settings to see which one works - it's part of the fun! Enjoy!:)

All times are GMT -5. The time now is 11:35 AM.