thanks for that. I've read that group shots should be shot at 50mm or more for a more flattering look, but this is 22m on a crop, would you advise moving back and zooming in slightly?
I have no idea where you read that. The flattering look comes from the perspective for the shot, and that is affected by the distance from the subject, not the focal length used.
If you were to try a headshot with a 22mm lens then you would get a slightly odd perspective, because you would have to shoot from a very short distance in order to fill the frame with just a head. That would emphasise features close to the lens, such as the nose, and diminish those further away, such as the ears. If you were to try a full length shot with the same focal length you would need to move further back, which would make the perspective less unusual. For a group shot you would move even further away, and there should be no problem of peculiar perspective. Using a focal length of 35mm equivalent, which is 22mm on a crop, should be fine. After all, is there enything unflattering about the image in the link I posted? My original shot was at only 40mm on full frame, which is equivalent to 25mm on a cropper. It does not look odd or unflattering to me.
In an ideal world you first choose where to stand for the shot and then you select the focal length necessary for the desired framing. Sometimes things like walls, rivers, fences limit your freedom to stand where you would like, or foreground obstructions (including other guests) limit your freedom to move further back, but you do what you can. Of course, you may also have creative goals to purposely use a wide shot, to take in a lot of the background scene, or a tighter shot to exclude background clutter.
Now, with that said, let's try some numbers. A good rule of thumb when shooting groups is to stand at least as far from the group as the group is wide and tall. e.g. if the group is 12' wide then stand at least 12' from the group. It so happens that a 22mm lens (35mm equivalent) will allow exactly that framing - 12' wide from 12' distance. That multiplies up of course. If your group is 20' wide then a 22mm lens will let you shoot the group from 20' away etc.. If your group is 8' wide then you could shoot from 8' away and so on. Ideally you would not want to shoot from a distance less than 8' due to perspective issues that would emerge. That isn't just about noses, but other factors too, like the fact that people at the edges of the group are further from the camera than those in the front and centre.
Now let's look at the DOF for the 12' wide at 12' distance figures for a 22mm lens.
At f/2.8 and focused at 12' (front row eyes) the DOF would cover from 8.5' to 20'. That's probably plenty for most group formations, with a safety margin for error.
At f/4 and focused at 12' the DOF would cover from 7.6' to 28'. It is hard to imagine that you would need a greater DOF than that for most group shots.
If you have a smaller group then let's look at the figures for 8x8 shooting....
At f/2.8 and focused at 8' (front row eyes again) the DOF would be from 6.3' to 11'. That could/should be fine for up to three rows of people. If you were to focus on the second row, let's say at 9.5', the DOF would be from 7.2' to 14'. That will include your front row people and many rows behind.
At f/4 and focused at 8' the DOF would be from 5.8' to 13'.
To sum all that up, for group shooting, a 22mm lens (35mm equivalent) used at not less than 8' from the group should give you a reasonable perspective and sufficient DOF for most group configurations even at f/2.8. For a little more safety, and perhaps improved lens sharpness then you could use f/4 instead. Just watch that stopping down more than necessary does not cost you in other areas such as shutter speed or ISO.
). My question - Is there any difference when shooting static shots in using AI Servo compared to one shot with my camera set-up ? 