DoF Study

[Gerry]

Hi;

In my on-going DofF study, I am curious about this image and wonder if my assumptions are correct in your opinion: http://tinyurl.com/ye9ctxg

1) Considering that large parts of the image are oof where they normally wouldn't be artistically, I presume this would be a hand-held shoot. 2) I presume this is a crop from a larger image since one would not normally be able to get this close a shot with a 310mm. 3) I would have thought one could have gotten a better image, artistically, with a much larger aperture, at least down to 4.5 which is as large as this lens goes. 4) A smaller aperture would have facilitated less ISO.

Is this correct thinking, IYO?

[GiantTristan]

My thoughts:

1. The head of the bird is very sharp. If there was camera shake due to hand holding, one would expect all parts of the image to be blurred.

2. I don't think that this is a crop. The photographer must have been rather close to the object to achieve the bokeh in the background.

3. If this picture were taken at f/4.5 rather than F/8, even less of the object would be in focus.

4. If you had reduced the aperture to f/11 you would have had a larger dof, and more of the pelican would be in focus. To maintain shutter speed you would have to increase iso by one stop which does not help IQ. Reducing the aperture below f/11 would further increase dof, but the onset of diffraction might reduce IQ.

[Gerry]

1) The right most of the beak is out of focus as are the feathers on the back of the head. 2) Except for shake. The body of the bird in front of the head is also out of focus. 3) Yes, that's my point. One would be able to shoot at a lower ISO and get more artistic bokeh as I said in my OP. 4) In my OP I actually meant lower aperture #, sorry.

[rpcrowe]

Shake causes all areas of the image to be OOF. When DOF is the problem, usually one or more areas of the image is sharp while other areas are not.

Regarding the comment: "get more artistic bokeh". BOKEH is controlled by the lens, specifically the number of blades in the aperture which determines if the OOF areas have a subjectively pleasing look.

[Gerry]

I think this thread has lost it's continuity and relevance to my OP. None of the responses have really satisfied my query. Perhaps I framed the subject incorrectly and it is best to end the pursuit. Thx.