DOF in bird photography-

Been batting this around a bit in the photo-sharing section-thought I'd post here to see if I could get another perspective or more insight.
A very accomplished member recently posted a series of very sharp Hummingbird photos. Turns out his exif was +/- 500-550 mm focal, f/8 aperature and 9-9.5 feet distance to subject. Body was MarkIII. My DOFMaster dof calculator indicates dof is around .04-.05 feet or about 1/2 inch. Yet the entire bird is in sharp focus. I have been struggling w/ issues that I thought were related here, but now I'm slightly confused. Any thoughts??

Thank you.

Could you link to the pictures?

Foggiest wrote in post #16921896
Could you link to the pictures?

Don't think that would add any meaningful info. plus they're not my pix. The owner of these images suggested that while 1/2" might be the "tack-sharp" dof, there is a +/- area of "acceptable" sharpness and that is what I saw there. I was just looking for other thoughts/opinions re:dof that tight even at a relatively small f-stop. Thank you.

Your DoFMaster program will be working on several assumptions. One of these is that the image will be printed at 10x8 and viewed from one foot. If you're looking at an image on a web page then it's likely to be smaller than 10x8 and you're likely to be viewing it from more than 1 foot away. Both of those will increase the DoF.

Another thing you have to consider is the angle the bird is relative to the plane of focus. I looked at the photos the OP is referring to and for the most part the hummers are pretty much parallel to the plane. That plus the small size of the birds accounts for the fact that most of them are in sharp focus.

hollis_f wrote in post #16921922
Your DoFMaster program will be working on several assumptions. One of these is that the image will be printed at 10x8 and viewed from one foot. If you're looking at an image on a web page then it's likely to be smaller than 10x8 and you're likely to be viewing it from more than 1 foot away. Both of those will increase the DoF.

OK-the scientific principles involved here pretty much escape my pea brain, but I guess it relates somewhat back to that "acceptable" sharpness that the photographer mentioned. Thank you.

ETS wrote in post #16921963
Another thing you have to consider is the angle the bird is relative to the plane of focus. I looked at the photos the OP is referring to and for the most part the hummers are pretty much parallel to the plane. That plus the small size of the birds accounts for the fact that most of them are in sharp focus.

These principles I can understand. And it means I have other issues besides dof w/ my hummer shots-mostly low light and slow ss. Thanks for responding.

Isn't DOF kinda of a term of convenience?
I mean there is only a single narrow plane that is in focus, the rest gradually falls off.
So the term of conveyance is one of human understanding/explaini​ng rather than absolute.

Kinda like the +- charge of electron

Small birds require a smaller aperture, and big birds can do with a bigger aperture.

To get an idea of the f stop required in different situations, one can make some assumptions, as follows.
- The bird being photographed mostly fills the frame
- The required DOF is 1/4 of the width of the field of view at the subject
- APS-C format

Then one needs to use the following f stop or smaller. This works for all focal lengths and shooting distances (those variables cancel out of the calculations).
- Goose f2.8
- Duck f4
- Crow f5.6
- Robin f8
- Sparrow f11
- Hummingbird f16

This is obviously a bit silly, because situations and requirements vary. But it shows a trend that is valid. Adapt as necessary.

ardeekay wrote in post #16921057
... Body was MarkIII. ..

which one? 10.5MP 1.3x, or one of the two 22 MP Full Frames?
Just curious.

Foggiest wrote in post #16922252
Isn't DOF kinda of a term of convenience?
I mean there is only a single narrow plane that is in focus, the rest gradually falls off.
So the term of conveyance is one of human understanding/explaini​ng rather than absolute.

Kinda like the +- charge of electron

Try to measure that depth of "gradual fall off" when your aperture, focus and focal length offer a hyper focal solution.

I suppose in a metaphysical realm, there might be a measurable fall off, (actually I don;t know if this IS how it works) but for all intents and purposes, everything is in focus, not one sliver a plane.

CyberDyneSystems wrote in post #16922331
Try to measure that depth of "gradual fall off" when your aperture, focus and focal length offer a hyper focal solution.

I suppose in a metaphysical realm, there might be a measurable fall off, (actually I don;t know if this IS how it works) but for all intents and purposes, everything is in focus, not one sliver a plane.

Not being cheeky here Jake, but I can't see it that way myself(in minds eye etc).
I see it as a human perception thing.

Even our level of equipment seems to detect differences within the DOF...

I think that it helps to understand DOF better to realise that it is not a set of depths like a ruler, but more a set of curves.
Makes more sense that way to me.

To paraphrase Hollis "Depends how close you want to look at it?"

CyberDyneSystems wrote in post #16922331
Try to measure that depth of "gradual fall off" when your aperture, focus and focal length offer a hyper focal solution.

I suppose in a metaphysical realm, there might be a measurable fall off, (actually I don;t know if this IS how it works) but for all intents and purposes, everything is in focus, not one sliver a plane.

Hmmmm, one common problem when people start doing wide-angle astrophotography is that they believe that they don't need to worry too much about getting the focus right because of the huge depth of field. One soon learns that, even at 10mm, getting the focus spot-on is very important.

If you focus at the hyperfocal distance then anything at infinity (like stars) will be right at the very edge of the 'acceptable' range of focus. But what is acceptable when shooting landscapes is far from acceptable when shooting starscapes. Using 10x with liveview and manual focus you really can see how the focus does 'fall off' as one moves away from true infinity.

CyberDyneSystems wrote in post #16922329
which one? 10.5MP 1.3x, or one of the two 22 MP Full Frames?
Just curious.

I checked closer-actually was a 5D MarkII.

Archibald-I think you just twisted my brain into a knot The largest bird-the largest aperature which yields the narrowest dof and the smallest bird the smallest fstop w/ the greatest dof? Seems like it should be the opposite. Looking at the 1/4 field of view for the req'd. dof thought-say you have an 8" field of view for a hummer equals 2" dof and likewise, you might have a 48" field giving a 12" dof. While this seems right to me, I'm missing how f16 and f2.8 give those dof's respectively. What am I missing

Foggiest, Jake, Frank-I'm going to have to ponder your thoughts-getting pretty technical for me.(See paragraph 1::o)