DoF vs focus point? I have a question for you expert shooters out there in Hogland. In some of my recent shots of white-crowned sparrows, like this one, I notice that the bird in the...

globetrekker Loc: Bend, OR

I have a question for you expert shooters out there in Hogland. In some of my recent shots of white-crowned sparrows, like this one, I notice that the bird in the back is not in sharp focus. Yet I shot in Av at F8, which I would have thought would be enough to get two birds only a few inches apart in focus. Now of course I put the AF point on the bird in the front, so that makes me think thats the cause. So is the lack of sharpness in the bird in the back to aperture being too wide open, or to the fact that I focused on the bird in the front? And if its not an F-stop issue, then how the heck do I get both birds in focus? Thanks for educating me

MWAC Loc: Somewhere East Of Crazy

How far were you from the subject?

DOF is caused a combination of the distance from the camera to the subject and the distance from subject to the background. The further away you are from the subject the smaller your plane of focus will be.

CaptainC Loc: Colorado, south of Denver

F-stop issue. Either that or tell the far bird to move closer.

GoofyNewfie Loc: Kansas City

Hard to tell, but it looks like the point of focus might be a bit in front. A lot of you probably know this, but for other readers, depth of field extends from about 1/3 in front of the point of focus and 2/3rds behind. Ie: you get more in focus behind than in front.

Nikonian72 Loc: Chico CA

MWAC wrote:

DOF is caused a combination of the distance from the camera to the subject and the distance from subject to the background. The further away you are from the subject the smaller your plane of focus will be.

Gotta disagree with you here. The shorter the Working Distance (WD), the more shallow the DOF.

At 6-inches WD, my DOF is about 1/4-inch at f/22.

(DOF varies with aperture & WD, and the plane of focus moves with lens focus, as a plane has no depth)

Nikonian72 Loc: Chico CA

GoofyNewfie wrote:

Hard to tell, but it looks like the point of focus might be a bit in front . . . depth of field extends from about 1/3 in front of the point of focus and 2/3rds behind.

This is correct.

My question: Are you manually focusing, or using camera auto-focus?

If manual, you may need to adjust your eyepiece diopter setting.
If auto, you should be using single center-spot focusing; then compose once focus is locked.

globetrekker Loc: Bend, OR

MWAC wrote:

How far were you from the subject?

DOF is caused a combination of the distance from the camera to the subject and the distance from subject to the background. The further away you are from the subject the smaller your plane of focus will be.

I was pretty close. Maybe 6-8 feet.

globetrekker Loc: Bend, OR

[quote=Nikonian72]

GoofyNewfie wrote:

My question: Are you manually focusing, or using camera auto-focus?

If manual, you may need to adjust your eyepiece diopter setting.
If auto, you should be using single center-spot focusing; then compose once focus is locked.

Used autofocus here, and pretty sure I did use single center AF point and recompose. Is it possible to use more than one AF point?

Nikonian72 Loc: Chico CA

globetrekker wrote:

Used auto-focus, and pretty sure I did use single center AF point and recompose. Is it possible to use more than one AF point?

Many DSLRs have menu choices of focal point sizes, number of points, and positioning of points. Part of the sizzle, but not really steak.

MtnMan Loc: ID

Probably more than you ever wanted to know about DOF:

http://en.wikipedia.org/wiki/Depth_of_field

You may want to check your camera settings regarding locking focus. Some cameras (including my Nikon D5100) give you the choice to set it up to lock exposure, focus, or both when you hold the shutter release halfway down or press the lock button. If you just lock eposure focus may move when you recompose.

If you have a Nikon and Nikon View NX2 it can show you the actual focus point.

RTR Loc: West Central Alabama

globetrekker wrote:

I have a question for you expert shooters out the... (show quote)

You did not mention the focal length you used so we can't calculate the actual depth of field obtained on this shot. I bet the camera focused on the rocks in front of the birds though. That combined with F8 gave a shallow DOF and put most of the area in focus in front of the subject.

julesreyesmarko Loc: Los Angeles

Increase the f stop to about f16, should get all the birds in focus.

globetrekker Loc: Bend, OR

Quote:

You did not mention the focal length you used so we can't calculate the actual depth of field obtained on this shot. I bet the camera focused on the rocks in front of the birds though. That combined with F8 gave a shallow DOF and put most of the area in focus in front of the subject.

I was at 250 mm - my maximum on my 55-250 lens.

globetrekker Loc: Bend, OR

julesreyesmarko wrote:

Increase the f stop to about f16, should get all the birds in focus.

But then I'd lose my isolation on the subject and show background things in focus that I don't want. I want creative control, and I shouldn't have to sacrifice that to get sharp focus. I tend to think this is a focus issue, not an aperture issue; but then again I am a DSLR newbie.

julesreyesmarko Loc: Los Angeles

then try different f stops between f8-f16. It's most likely the aperture. You won't lose your bokeh by increasing your f stop a little more.