Dept of Field Data

[HDNitehawk]

I’m afraid an in-camera DOF calculator isn’t that easily implemented. There are a few important parameters unknown to the camera: The size of the final image/print, the viewing distance and the eyesight of the viewer. And if you don’t know these parameters you can’t calculate the DOF.

Print size wouldn’t matter as far as the calculator goes. The camera does know focus distance, it displays this in the exif files with some programs. My near sightedness doesn't affect the DOF of my pictures. I think it is easily implemented, and should be as accurate as the ones that are on-line. On-line calculators only need to know a few things; lens, aperture, distance and sensor size. All of the pieces of information are available in camera.

[cls]

Print size wouldn’t matter as far as the calculator goes. The camera does know focus distance, it displays this in the exif files with some programs. My near sightedness doesn't affect the DOF of my pictures. I think it is easily implemented, and should be as accurate as the ones that are on-line. On-line calculators only need to know a few things; lens, aperture, distance and sensor size. All of the pieces of information are available in camera.

Yes, but when they need to know sensor size it's because it is put in to the "magnification factor" calculation (from sensor size to the assumed print size of 25 cm / 10 inch long side). The assumption of the viewer's ability to distinguish 5 lp/mm at a viewing distance of 25 cm is also built in (typically these parameters are not inputs to DOF calculators). But sure, the same simple algorithm as can be found in various DOF calculators could be implemented also in cameras. But the result would still be based on assumptions.

[HDNitehawk]

Yes, but when they need to know sensor size it's because it is put in to the "magnification factor" calculation (from sensor size to the assumed print size of 25 cm / 10 inch long side). The assumption of the viewer's ability to distinguish 5 lp/mm at a viewing distance of 25 cm is also built in (typically these parameters are not inputs to DOF calculators). But sure, the same simple algorithm as can be found in various DOF calculators could be implemented also in cameras. But the result would still be based on assumptions.

That would be true, since the DOF is subjective. Any calculator you have will be the same.

[neuroanatomist]

The camera does know focus distance, it displays this in the exif files with some programs.

I wouldn't put it quite so strongly. The camera records a value for focus distance in the EXIF, that I won't dispute. But sometimes that value is egregiously inaccurate, making any reported DoF estimage what the engineering folks call a WAG (wild-ass guess).

[iND]

Thanks for all the great discussion. This is why I keep coming back to this forum.

I would settle for some inaccuracies in the DOF calculation it would not have to be exact.
Like I said maybe just a idiot light with an adjustable setting:
Something like a blinky if the DOF of field falls below a preset value.
Example: If my DOF panic light (even if not accurate to the cm) would blink if say the DOF fell below 1 meter, then I could back up and reframe, and not suffer the to post processing disappointment.

I would even settle for the values in the app based softwares that use the known data

Here is a good example where I started a series of shots then moved in to fill the frame, forgetting that my DOF fell to 27cm at one meter.
Result is (since I used a tight group of focus points (Mark III) the second girls is unacceptable. Not anyones fault except my own as I failed to think
SHRINKING DEPTH OF FIELD as I moved in. Wish I would have had a quick reminder. I could have simply stepped back, filled the frame with some unwanted detail but that could have been an easy crop in post processing (starting with 22mpx and is no big deal)