where to focus if shooting 2-4 ppl together and wt are the best settinggs

Started Jul 29, 2012 | Discussions thread
Wally626 Senior Member • Posts: 2,312
Re: where to focus if shooting 2-4 ppl together and wt are the best settinggs

You are correct that in some cases the typical shallower depth of field for APS-C sensors versus P&S will be a problem. First step know there may be a problem.

This is not usually an issue in good light as you can stop the lens down enough to get the DoF you need and still keep a good shutter speed. There are several on-line calculators that will give you a rough estimate of the DoF for various f-stops, focal lengths and object distance. When you are shooting large groups, two trends help, you will tend to use shorter focal lengths or longer distances, both help increase the DoF. As far as where to focus, I would focus on the eyes of the most important person. If many or equally important people focus on the front row center eyes for 2 deep, center row for 3 deep.

Example case, 50mm lens want to take a picture of a group that is 4 wide. Distance is about 15 ft. Using circle of confusion values for a Canon 550D, your depth of field is at f/8 is about 9 ft. So plenty of depth for a small group. At f/4 it drops to 4 ft. Should be OK for two deep but marginal for 3 deep. At f/2 it is 2 ft, might be too little even for single deep if they are not lined up parallel to the camera.

As you can see you want to set the aperture sort of in the middle of the range f/5.6 f/8, f/11 etc. however you need to keep the shutter speed up as well. Subject movement, unless you can get them to stand really still, means at least 1/200th second. At least 1/100th for hand shake. In poor light you run into the issue of keeping the aperture small enough to have everyone in focus, the shutter speed high enough to eliminate subject and hand movement and keep the ISO low enough to avoid a lot of noise. Sometimes the answer is flash, but newer cameras do allow for pushing the ISO higher and higher so less situations are going to require flash.

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