CoC Management and the Object Field.

Started May 28, 2016 | Discussions thread
Jerry Fusselman
Jerry Fusselman Contributing Member • Posts: 886
CoC management: Cannon over Placentia (challenge)

One of the more challenging images in Merklinger's simpler book on the object-space method, is on p. 48, which I call "Cannon overlooking Placentia, Newfoundland."

The challenge: What aperture and focus distance do you use?

I plan to discuss this example in some detail shortly, because I've simulate CoCs based on both defocus and diffraction for several different CoC management plans. The plans compare different methods, including Merlinger's object field method.

The challenge is to manage depth of field for the best image according to your taste. If the image does not please, you could imagine that the Placentia C of C is your client, and they want a large print.

Some information gleaned from the Internet and the lens equation:

  • The 12-foot (bore) canon is 50 feet away.
  • The foreground pine trees are perhaps 75--150 feet away.
  • The buildings you can see in the town are 2160--5280 feet away.
  • The distant trees may well extend to five miles away.

Jim answered the challenge in the earlier thread, but I had not yet given this data about distances of key objects in the image.

I don't want to limit your creativity, but consider assuming the following for the sake of focusing on CoC-management issues:

  1. Lens, a superb 90mm
  2. Camera, maybe the best in FF for this image, a Sony a7RII 42 MP.
  3. with tripod; wind not terrible
  4. Camera position, time of day, season, weather, all match Merklinger's situation.
  5. Just one image; no panorama, no tilt-shift, no focus stacking
  6. You can plan deconvolution, sharpening, contrast enhancement, etc., as global changes in post.

Jim's answer is strong, of course, but it has some surprises, and we can still compare the object-space method to the image-space method to see which works better according to our tastes.

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Jerry Fusselman

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