Why is the little guy out of focus here?

[kristenh]

I'm puzzling and puzzling here:



here's the exif data:

nikon d5000
focal length 35 mm
f 3.2
shutter speed 1/250
iso 200

i would have thought with that aperture i'd have enough DOF for both boys to be in focus. and the shutter speed is too fast for it to be camera shake or movement, right? what do you think is wrong? TIA

[candidrachel]

He looks ok to me. I think its a lovely moment.

[MrJones]

ok, checking the photo at it's large scale - he is blurry but he is not out of focus.
my guess is that he was laughing and moving constantly and what you got here my friend is motion blur. just look at his hand.



1/250 is fast... but not THAT fast.
btw, the guy holding him is out of focus too. but that's focus issues, not motion issues

[Photologyst]

Yep! Motion blur.

You could sharpen the eyes and mouth, then motion blur the hands more and voilà!

[RichardTaylor]

I think it is a combination of two things.

(1) Motion blur especially for the hand.
(2) And a slightly too shallow DOF
Without knowing your subject distance it is a bit hard to be exact. However you may find this DOF calculator may give you an idea of what you get at F3.2 (not a lot - like about 6" (150mm) in front of the point of focus (the rear boy) if you were shooting 6' (2m) feet away)

Online Depth of Field Calculator

[kristenh]

Hm, thanks for the replies. Rachel, thanks for the compliment. these are two of my sons- and the big one was home from college, which is very exciting for the littles. they were tickling/being tickled so i guess no surprise on the motion blur, Mr. J. Photologyst- learning that stuff is on my to-do list, esp the sharpening. and Richard T- wow, here i thought i was really getting a lot of depth of field stopping down to 3.2 or whatever it was. so i wonder how people get such nice sharp shots of multiple people plus blurring in the background? a loooong lens?

[RichardTaylor]

Most of my people shots are candids.
However my thoughts
Try to have the people on the same plane (distance from you) if you can't do that then have the background in the distance as far away as possible. A longer focal length does help as you can be further away from your subject but the background will be brought in closer however the DOF will drop of very rapidly..

A couple of examples from my Flickr stream

(1) Both roughly on the same plane. Notice the city street is a bit blurred but not a lot. (It's not that far away.

Camera Canon EOS 40D
Exposure 0.003 sec (1/320)
Aperture f/4.0
Focal Length 78 mm
ISO Speed 200
Exposure Bias -1 EV
Subject Distance 4.55 m (~15 feet)

(2) Not on the same plane However I am shooting at 19metres (62feet) so even at F4 and 140mm I have approx 9' (3m) DOF to cover the whole group. Notice the background is nicely blurred.
The pic has been slightly softened when PPing.

Camera Canon EOS 40D
Exposure 1/3200 sec
Aperture f/4.0
Focal Length 140 mm
ISO Speed 400
Exposure Bias -1/3 EV
Subject Distance 19.1 m (~62')

(3) However it can be a fine line.
Same camera, aperture & shooting distance is the same. The only thing now is I am at 200mm and my DOF has halved. If I wanted the person in the background sharp I should have been around F8

Camera Canon EOS 40D
Exposure 0.001 sec (1/2000)
Aperture f/4.0
Focal Length 200 mm
ISO Speed 400
Exposure Bias -1/3 EV
Subject Distance 19.1 m (~62')

Hope this helps.
Richard

[SusanH1970]

Richard, the DOF calculator was confusing to me for a long time, being a visual/tactile learner. I figured it out, but I'd have figured it out MUCH sooner if you'd posted this earlier. Fantastic examples of how focal length, aperture, and distance work together. Please post this in the tutorials section, if you don't mind.

Oh, and I'm totally adding you as a friend here, LOL.

[RichardTaylor]

Thanks very much for the nice words Susan. I will use it as a basis for a tutorial. Should be up in a day or two if I can use existing photographs..

[RichardTaylor]

@ kristenh

Have a look at this very basic tute of mine, it will give you an idea of what to expect
DOF Notes:1 - Head shots using a 50mm lens.