DOF on digital cameras

[sevo]

DOF depends on the size of the film or sensor, focal length of the lens, distance to the object and aperture, but not on someone illusion.

Not illusion, but perception has to some degree superseded technical standards, where DOF in the digital era is concerned. The entire concept of DOF revolves around the amount of acceptable blur - the "circle of confusion". The ability to pixel peep has had many digital camera users downsize their personally accepted CoC to the level where there is no discernible blur - that is, down to less than one (de-mosaiced) pixel in diameter, which is much less than what lens makers assume as the CoC when calculating DOF scales.

 

[Roger Hicks]

DOF depends on the size of the film or sensor, focal length of the lens, distance to the object and aperture, but not on someone illusion. . . .

And print size and viewing distance, and lens type (soft focus appears to have more DoF) and paper surface (coarse surfaces appear to have more DoF). And expectation. So mostly, yes, it is illusion, as is most visual perception. Consider Richard Gregory's Eye and Brain or The Intelligent Eye. If you haven't read them, do.

Cheers,

R.

 

[Ko.Fe.]

Thank you, Roger, will try to read it.

Not illusion, but perception has to some degree superseded technical standards, where DOF in the digital era is concerned. The entire concept of DOF revolves around the amount of acceptable blur - the "circle of confusion". The ability to pixel peep has had many digital camera users downsize their personally accepted CoC to the level where there is no discernible blur - that is, down to less than one (de-mosaiced) pixel in diameter, which is much less than what lens makers assume as the CoC when calculating DOF scales.

Where is no marks for two and three centimeters on any DoF scale of the lenses I ever seen and used. Have you tried to pixel peep on portrait taken with 21MP 5D MKII and 50L at f1.2 from one meter? I did. With DOF of three centimeters here is not so much to peep at.

But if your DoF is in meters downsizing of 21MP picture to 640x480 will give you very sharp image from corner to corner.

 

[job]

Far too many people look for more precision in photography than exists. There's a whole piece about DoF at http://rogerandfrances.eu/photography/dof where I discuss the variables involved, including camera shake (which is often ignores in such discussions), with examples.

Cheers,

R.

Thank you so much Roger for your excellent article that answers all my questions

Regards,
Job

 

[Spanik]

I find that my tolerance of shake changes far more than of (perceived) dof when going from film to digital. Maybe I now see shake for what it is and don't think it is dof.

 

[Roger Hicks]

Thank you so much Roger for your excellent article that answers all my questions

Regards,
Job

Dear Job,

Thank'ee kindly for that comment. I can't live on appreciation, but at least a comment like yours shows that I am not wasting my time when I try to explain things.

Cheers,

R.

 

[nongfuspring]

1 Not really. See my original link. A preview is NOT the final image size or viewing distance.

2 Not really. You can never be sure what autofocus is going to focus on.

3 Only if you have plenty of time.

4 Not really. "Acceptable" DoF is constant on film and digital. All that changes is your definition of "acceptable".

Last para: I've found them a useful guideline for the last 50 years, even if you haven't.

Cheers,

R.

I think you may be misunderstanding me.

1. That is a different issue, this is about DOF scales vs direct alternatives. You get a better indication of DOF characteristics with preview (mechanical or live view) than numbers on a lens barrel.

2. Again, this relative to the reasons why DOF scales are not common on digital cameras. AF systems may not be 100% accurate all of the time but they're accurate enough for most people to not bother with hyperfocal.

3. Auto ISO, aperture priority. Only full auto would be faster.

4. Which is was my point. With an 6 megapixel 35mm tri-x shot vs a 36 megapixel FF sensor at the same aperture and focal distance will much more easily show errors in focus. I think you say as much in your article re: print sizes.

 

[willie_901]

That is where AutoISO comes into play. Set minimum shutter speed you want and you can shoot aperture priority with the camera using your aperture, your minimum shutter and it will set ISO to make it work up to your max ISO.

You can even do this with full manual aperture/shutter. Pentax has their Tav mode and the Fuji's do basically the same thing. Put the camera in Auto ISO and set the camera to manual exposure mode. You set shutter/aperture the camera will set ISO to make it work.

Very quick to shoot this way.

Shawn

Much quicker to use an ISO-invarient camera with raw files. Just set ISO to the base value (native sensor's ISO) and adjust global brightness during post production.

 

[anerjee]

In my experience, film images can live with a certain amount of unsharpness, sometimes quite obvious even at moderate print sizes. It just works if the other elements in the image are there.

In digital, it does not work. Even limited amounts of unsharpness (due to limited dof or camera shake) can spoil the image and make it look sloppy work.

My *extremely* personal views, of course.

There really isn't a significant difference in thinking about and using DOF between film and digital cameras. I use the word "significant" based on my experiences and expectations. No doubt others will have different views.

 

[shawn]

Much quicker to use an ISO-invarient camera with raw files. Just set ISO to the base value (native sensor's ISO) and adjust global brightness during post production.

Shooting ISOless means more time in post. I'd rather be shooting. It is also not faster than using autoISO with a camera that has great JPEGs.

Besides, IME so called ISO-invariant cameras aren't. X-Pro 1 was supposed to be but I always found more noise shooing that way vs RAW and adjusting ISO in camera. X Pro 2 was originally said to be the same and I demonstrated that it wasn't shortly after it came out. Then the info about it being two stage came out.

But then with my Fuji's I only rarely shoot RAW. Too many people use RAW as a crutch to 'fix it in post' vs. just getting it right in the first place. That is assuming the camera has a good JPEG engine of course, not all do.

Shawn (former RAW only shooter)

 

[JoeV]

The problem I have with depth-of-field discussion threads (which begs the question that if I have a problem with the thread, why am I posting? But that's the subject of another thread...! ), besides the fact that they run on and on with everyone repeating each other (like I'm probably doing here...) is that many seem to be operating under the assumption that depth-of-field is a binary function (i.e. good/no good; soft/sharp; etc.), and seem to be expecting the scale on the lens to be telling them this soft/sharp decision in crisp, binary values; whereas it's really a continuously varying optical function, and the scales are, despite (usually) being engineered to some standard, essentially entirely arbitrary to some presumed assumptions made by the manufacturer that very likely has nothing to do with the pictures that you actually create.

What's an acceptable level of blurriness depends on many things beside viewing distance of the print and reproduction ratio. It's really an aesthetic taste, which numbers on lens scales simply can't decide for you.

The only thing useful a DOF scale can tell you is relative focus at the various aperture settings, based on your experience with that same lens/film/sensor/workflow combination.

F/8 or F/11? Depends. But the scale isn't going to tell you if it's art/not art/bad art. Which is what it sounds like many people are seeking from their lens scales.

~Joe

 

[willie_901]

...Too many people use RAW as a crutch to 'fix it in post' vs. just getting it right in the first place. That is assuming the camera has a good JPEG engine of course, not all do.

Shawn (former RAW only shooter)

So, before digital imaging did too many people also "fix it"in the darkroom?