DOF and Hyperfocal Distance

[Ollokot]

Hi Folks,
There have been a few threads recently on maximising Depth of Field so I decided to have a serious try at Hyperfocal Distance. The equipment used is a Canon 50D with a Canon EF 16-35mm 2.8 L ll Lens. In the first shot you see the focus point used was the bottom left one focused on the near subject, the seat, with an aperture of f/16, and at 16mm this is the usual method that I use.



This next shot I used the same focus point on the same near subject, the seat, (a different composition which in hind sight I should not have done in order to keep the same perspective).
To obtain the hyper focal distance I multiplied the mm setting of 16 by itself = 256, the aperture to be used f/8 was multiplied by the circle of confusion = 0.019 which = 0.152. Then 256 was divided by 0.152 = 1.68 Metres.
Then with the distance from the near subject to the focal plain obtained I focused (manualy) on the subject using the bottom left focus point. With the full resolution image there seems to be a marked difference in sharpness through the image using this method. The images posted are at 1200 pixels on the long side, I hope you can compare them at that size. I would be most grateful for your observations and for your corrections if I am totaly on the wrong track. Here is the second image shot with the settings listed above.



Best Wishes Pat.

[Donald]

I'd say you've got it spot on there, Pat.

I used the window on the gable end of the church and the grass right at the bottom of the frame, in the centre, as points of reference.

It's not huge and it is difficult when we don't have exactly the same shot, but it seems to me that you've successfully put the theory into practice.

[Mike Buckley]

I need to carry a calculator in my bag now?

[Andrew1]

1/3 of the way into the view is faster although not as accurate. Or you can carry around a DOF chart for your lens. Or you can use http://www.dofmaster.com/iphone.html

I find your first shot a better DOF . Enlarged, the foreground blades of grass are acceptable and the antennae on the chimney of the yellow building is more distinguishable.

[pnodrog]

On the Canon D50 I think on the left hand front below the lens release button there is a little button for DOF preview and if you press it while looking through the viewfinder you will see the extent of the focus range. It is sometimes a bit dim but if you allow time for your eye to adjust it is still the best way of adjusting the region of critical focus. For me seeing is believing and charts are for reading at home or as a reference in a studio.