Question about focusing a 4-months old

cdifoto wrote in post #7339218
Hoff, have you ever photographed a baby? They can seriously kick, squirm, and buck! I could see her sitting upright over her legs and then jerking back in an instant. It happens. A lot.

Dude... every day for the past 5 months and 8 days. About 4,000 frames I'd guess. And he MOVES. Never stops.

The focus is on his wife's knees -- was she bucking back and forth as well?


bucking baby @ f/2, outer AF point

cdifoto wrote in post #7339218
Hoff, have you ever photographed a baby? .

lol ... this should be good

TheHoff wrote in post #7339256
Dude... every day for the past 5 months and 8 days. About 4,000 frames I'd guess. And he MOVES. Never stops.

The focus is on his wife's knees -- was she bucking back and forth as well?


bucking baby @ f/2, outer AF point

I never said they ALWAYS buck back and forth. My nephews are always on the move as well, but they squirm like mad on someone's lap. That child in your photo isn't even close to "bucking" around.

Besides, your technique is solid. You didn't focus-recompose.

cdifoto wrote in post #7339320
I never said they ALWAYS buck back and forth. My nephews are always on the move as well, but they squirm like mad on someone's lap.

But look at the distance -- from wife's knees to wife's chest? If the baby is bucking that much, you need to take a break, calm them down, and try again later.

Normal baby movement I might expect the focus to be on the kid's buttons or on the kid's ears-- I get that occasionally if I'm not quick enough on the shutter -- but that must be 8 inches the focus is off by.

And another argument against focus/recompose with kids is that delay between the two events is giving them another chance to move. Use an outer AF point or if that isn't reliable enough for you, compose loosely, use center AF, and crop in post. We have more than enough MP now to make that workable.

He is rocking back and forth on his stomach as he learns to crawl so I don't know how much more back and forth movement you'd like to see. And yea I'm not arguing that my kung fu is the best just that your focus might be off by an inch or two if technique is the issue -- the OP's focus is off by 8 inches or more.

I'm not saying it's normal/typical/continu​al or that OP isn't making like a Sears Portrait studio and torturing the poor thing, but it happens. I mean, the kid doesn't look like she's in a position of comfort in that shot. It looks to me like she squirmed backwards from a significantly more forward position while he was doing his little focus-recompose dance.

We'll agree to disagree then. I don't think his wife was bucking around so her knees moved the same amount, but if that is what you posit, I can't prove you wrong.

Of course the wife isn't bucking around. I never implied that. I said that the little girl could have been leaning forward more...even with her face right over her legs. Infants don't always sit STRAIGHT up you know.

No that it matters. Neither of us was there. The point really is that OP's technique of focus-recompose is NOT going to fly with fast apertures AND a moving subject. It rarely ever works with fast apertures and a non-moving subject.

To summarize:

Focus-recompose sucks!

Ohh I see what you mean about leaning forward, catching focus, then leaning back... yup, that could happen. You would hope, though, that with digital you would take enough frames that the bucking would be so much of an issue.

Like I said, I'd expect an error of an inch or two every few frames but if this is the best you got, there is some major technique (or hardware) flaw here.

I'll agree with that, definitely. If that's the best and there was no actual bucking, there's got to be something totally out of whack. Even focus-recompose isn't usually that far off. Unless OP is in AI Servo and trying to focus-recompose.

Thanks all again,

I will try using those off-center focus points next time shooting the baby and not using the "recompose" technique just to sort things out(really need to wait for the good mood from both mother and baby ). I am shooting with an XSI body and 50mm 1.8 lens, not sure if this is related. Over the past couple month, I realized that the focus between 1.8 to 4 is hit and miss. Btw, I was shooting my baby at my max sync speed (1/200) already.

Another reason I am thinking is because I am standing like 7feet away from my baby and thats why focusing on her eyes is not as obvious (to the camera) as standing very close to her because her eyes are not always open at full. Does this make sense at all?

If you allow the camera to choose what it thinks it should focus on, it will pick the most contrasty part of the scene, even if that's not what you want it to focus on. Choosing the focus point yourself will help avoid that. You can tell the camera where to focus by selecting a specific focus point, and putting that on the eyes, rather than letting the camera guess at what you want. Choosing an off-center point will allow you to do that, and avoid the possible focus-recompose issues discussed above.

iamdogdog wrote in post #7340552
Over the past couple month, I realized that the focus between 1.8 to 4 is hit and miss. Btw, I was shooting my baby at my max sync speed (1/200) already.

The reson focus is hit and miss is probably because yje depth of field is so narrow. If you recompose you will likely miss focus most of the time. If the subject moves a few cm you will also likely miss focus. There is no need to use the flash at the max sync speed..... learn how to mix ambient with flash and your exposures will look better 9and your batteries will last longer)!

iamdogdog wrote in post #7340552
Another reason I am thinking is because I am standing like 7feet away from my baby and thats why focusing on her eyes is not as obvious (to the camera) as standing very close to her because her eyes are not always open at full. Does this make sense at all?

The eyes to not need to be open. You need to set the focus point and make sure that it's set on the eyes. Don't recompose - use the best AF point.

You can recompose if you select a suitable smaller aperture - more depth of field allowing more leeway in terms of acceptable focus.

TheHoff wrote in post #7339256
Dude... every day for the past 5 months and 8 days. About 4,000 frames I'd guess. And he MOVES. Never stops.

The focus is on his wife's knees -- was she bucking back and forth as well?


bucking baby @ f/2, outer AF point

Hi TheHoff, are you focusing on his eyes as well? How far between camera and him(did you crop)? I will try to do the same distance thing as you so I can sort things out.

Thanks.

iamdogdog wrote in post #7343335
Hi TheHoff, are you focusing on his eyes as well? How far between camera and him(did you crop)? I will try to do the same distance thing as you so I can sort things out.

Thanks.

Hi,

There is no crop on that file. I'd back up a bit from my shot here as the closer you get, the more difficult it is to obtain the best focus.

Rather than try again with your daughter, I might try some static objects in the same size / distance range. Make sure you can get proper focus with your technique and your equipment when you know the subject is not moving. Sometimes when I'm setting up lights for my boy, I'll put one of his stuffed monkeys in the shot where I want him to be to check the lighting and shadows -- this would also work for you. Just grab a doll and put them in a similar position. Make sure your shots are right on with that first and then go to a moving target.

another question, would getting a speedlight (430ex or 580ex) or ST-E2 helped me with a more accurate focus in this situation? Or those will only helps me in low light condition?

thanks.