keeping focus when multiple people are in the picture.

Comments

• bruto

  November 2017

  That's a complicated issue with a few variables but here's one way to look at it.
  
  First of all, if the people are close together and side by side, it's probably all right to focus on one, and expect the other to be in focus too. The further apart they are, the less likely this is, and one way to get around this is to stop the lens down to increase depth of field. You're probably still best off by trying for someone's eyes.
  
  When people are at different distances, the issue becomes a little more complicated. You will simply need more depth of field. How much adjustment is needed will vary with aperture, focal length and distance. The wider the lens, the more depth of field. The further away, the more, and the smaller the aperture, the more. Given the choice between a shorter focal length and a shorter distance, the shorter focal length will give you slightly better depth of field even though it's decreased by having to get closer. Often with a group photo it is simply impossible to achieve uniform sharpness without stopping the lens down more, and sacrificing the out of focus backgrounds that are generally favored for individual portraits.
  
  There is a practical limit to shorter focal lengths, as wide angles give an exaggerated perspective, and in a group will tend to make the center subjects appear larger and closer, and in extremes will be unkind to facial features, and any variation from the level will also produce radical vertical perspective. You should not need ordinarily to go that wide or that close. Wide angles can give a dramatic effect when you want it, but embarrassing distortion when you don't.
  
  You can also gain some depth of field if necessary by shooting from further away and then cropping in. This permits a somewhat wider angle lens, with correspondingly better depth of field. That's often not the best solution, but the D3200 has pretty generous sensor real estate, and a decently sharp image can be cropped considerably with little loss. This is most true if you can keep the ISO low and minimize post processing corrections, and better still if you shoot in Raw mode and crop the Raw image in a program like View NX-2. The crop is done in raw mode before conversion to JPG and it's a bit sharper than cropping a JPG. It will depend a little on how big you print, too. It's worth experimenting a little. You may be surprised how much you can crop an image when you're not printing it very large. Remember too that if you're printing, say, a 4 x 6, much of the imprecision you see when you pixel peep on the computer will be invisible.
  
  There's a sort of rule of thumb, which is only really useful at middle range with middle focal lengths, but can be good to remember in portraits. This is that the depth of field will be greater behind the focus point than in front. The sort of rule of thumb is that you'll get about 2/3 of your DOF behind, and 1/3 in front. For this reason, if you are taking a group of people at varied distances, you'll probably get the best overall focus if you focus on one of the closer subjects. If there are two not too far apart, focus on the closer of the two. If many, find one who is a bit more forward than the center of the group. This rule disappears with longer focal lengths and distances, but is at least close for the distances usually used for portraits.
  
  Finally, another small point probably rarely an issue here, has to do with focusing and recomposing, That's often the best way to go, but when you focus and recompose, you generally move the camera in an arc. For this reason, when depth of field is very shallow, you may actually change the distance of the camera from the thing you focused on at first, and lose sharpness. If you focus on a person in the middle, then recompose to put him off to the side, he will end up closer to the camera than you bargained for. If your subjects are fairly close, and you need to focus far off center, you'll get better sharpness by moving the focus point to the desired subject than by moving the camera after focusing. This problem decreases to no problem at all at longer distances and smaller apertures.
• PBked

  November 2017 edited November 2017

  Hi
  All good advice from @BRUTO as usual. He really does know his stuff unlike me. However, one little trick I learned in this situation was to place the second person behind and slightly to the side of the one in front so effectively he/she is looking over the first person's shoulder. Fill the frame with this shot and, allowing for Bruto's advice on depth of field, focus on the ear of the person in front. You won't need to worry too much about background with this scenario and you will get a photo that really pops.
  Regards
  PBked
• bruto

  November 2017

  That is a good idea, if your subjects are within your command. You split the depth of field without having the people dully next to each other, and a tight shot will have more impact as well.