group shot oof issues...

[artra]

Here are a couple of shots from this afternoon w/ my family.
Pretty much taken one after the other, the first shot seems like everyone is more in focus, but the second one not so much. What's the trick? I think I was shooting on "one shot" as oppose to "ai servo".

1. f/4 1/400 iso 100 focal length 50mm
http://farm3.static.flickr.com/2423/4028249044_4fb7f88c8c_b.jpg

2. f/4 1/400 iso 100 focal lenght 60mm
http://farm3.static.flickr.com/2744/4027500275_a059e1a546_b.jpg

[sapearl]

Hi Artra - at f/4 your DOF is pretty shallow and at 60mm it will appear even more so. The front row kids are in sharp focus, which is where I assume you had your focus point. But the 2nd row is OOF.

At that close distance you really need something more like f/8. Also, your ISO is a bit on the low side. If you had increased the ISO to 400 (from 100) that would have gained you two more stops to thef/8 I suggest. Hope this helps. Btw, cute family ;). - Stu

[joedlh]

In the first shot, the pumpkin in the bottom left corner is OOF, as you would expect it to be. It looks like your camera properly focused on the kids in the front row. In the second one, the kids' sneakers are sharp and the pumpkin is pretty sharp too. I suggest that the focus was pegged on the pumpkin held by the second kid from the left, which put the back row out of focus.

One shot is appropriate in this situation. However, make sure that the active focus sensor is actually aimed at the right thing. Many photographers will select the central one because they've been burned by the camera deciding what should be in focus when they're all selected. Similarly, many photographers will not use AI Focus at all, again, because of bad surprises. I have found that AI Servo is not good in this setting because without a single obvious subject it shifted focus to the background on me more often than I would like to say.

[ScottKCooper]

I'm just glad you gave them all a hat to match yours ;) cute family. i agree on the dof comments.

[TheHoff]

Is this at 1/400 shutter with flash? that would explain the dark band at the bottom -- the shutter speed is too high for the flash unless you hit that H button on the flash to put it into high-speed sync mode (you lose power output but gain the ability to use higher shutter speeds).

[joedlh]

Is this at 1/400 shutter with flash? that would explain the dark band at the bottom -- the shutter speed is too high for the flash unless you hit that H button on the flash to put it into high-speed sync mode (you lose power output but gain the ability to use higher shutter speeds).

You're right. I meant to mention that, but got distracted by the focus issues. I curse my short attention span.

[artra]

guys thank you VERY much for your helpful comments.
to tell you the truth I didn't know much about DOF until you guys pointed out.
now I'm trying to educate myself about this important part of group photography.
yes, I realized 1/400 is way above 1/250. I guess I didn't trust 1/250 would freeze my kids in case they'd move around suddenly.