Must watch video on full frame vs crop cameras. "Full frame look" covered.

[tupp]

So the argument is: Higher ISO -> more processing that lowers effective resolution -> larger acceptable circle of confusion -> deeper depth of field.

No.

Post-capture processing and the "acceptable circle of confusion" don't affect the depth-of-field.

Depth-of-field is an optical property that exists regardless of whether or not the image is captured.
 
 

What it does is make more of the scene be equally just-out-of-focus, to put it one way, because the lower resolution is inherently less sharp and so more of the image will be "sharp enough."

I seem to recall reading a similar point somewhere in this thread.

[Quirky]

bollocks.

 

My thoughts exactly.

Although the meme does appear to be a highly efficient nerd trap, even here. Which is somewhat surprising. But still, it's bollocks. Utter waste of everyone's time. Another nerdy meme not worth propagating.

 

Seriously people, no one is 'cheating' you. Forget the jargon and ignore the nerds, just grab your camera and go out to shoot something with it. If the footage or photos you get look good to you, great, that's all that matters. Regardless of the sensor size of your camera, or the F-stop carved on your lens barrel.

[AndrewM]

No.

Post-capture processing and the "acceptable circle of confusion" don't affect the depth-of-field.

Depth-of-field is an optical property that exists regardless of whether or not the image is captured.
 
 

I seem to recall reading a similar point somewhere in this thread.

 

Sigh. This is what you get for trying to be a peace-maker and explain how both sides have a point....

 

Depth of Field is an optical property. But it is a property with a free parameter, to use technical speak on you. You have to specify a circle of confusion. Otherwise the depth of field (for an optically perfect system) is always zero. There is exactly one distance where the light is focussed to a mathematically perfect point, regardless of aperture. (In the real world, there is NO distance where this happens, so there is no (perfect) depth of field.) What counts as "the area in focus" depends on what you mean by "in focus," and you can't mean "perfectly in focus" because then the answer is always zero.

 

The free parameter is the circle of confusion. If you don't specify a value for that parameter, then there is no depth of field in any meaningful sense.

 

The point (and oh my god I feel stupid even as I type this, like I am being sucked into some kind of internet madness...) is that what is a reasonable value for this parameter depends on the resolving capacity of the system (film, digital, or whatever) that you are talking about. Nothing optically changes, please let us all accept this. But the number you get for depth of field will change when you change the number for the circle of confusion, and it is not completely unreasonable to change the number for the circle of confusion if the resolution changes.

 

Everyone is right.

 

Please let it end.

[Axel]

My observation is, that while you can match the DoF of, say, 5D MII, 7D, GH2 and BMPCC with the lens math above (respecting only 'optical properties'), you will still have subjectively different looks. The EOS cameras above have the lowest resolution (though particularly the 5D can look as if it had superior resolution, but it's aliasing to a great percentage, see this ancient article). Yet it's still an ambiguous 'Full Frame Look' everybody accepts as measure.

 

Those factors that do contribute to DoF (let alone look), but are 'ignored' in the calculation, are not ignored because they are neglibible, but because they can't be generalized.  

 

And if we agree that a general rule of thumbs suffices, then it was: Buy the fastest lens ...

[jgharding]

With every post i read, I feel I unlearn a little

 

If this carries on I'm dusting off the Sony Z1

[tupp]

Depth of Field is an optical property. But it is a property with a free parameter, to use technical speak on you. You have to specify a circle of confusion. [snip] The free parameter is the circle of confusion.

That "free parameter" is determined by a fraction of the focal length, not by sensor/film resolution.

[AndrewM]

That "free parameter" is determined by a fraction of the focal length, not by sensor/film resolution.

 

Um...no.

 

To quote from wikipedia:

 

In photography, the circle of confusion (“CoCâ€) is used to determine the depth of field, the part of an image that is acceptably sharp. A standard value of CoC is often associated with each image format, but the most appropriate value depends on visual acuity, viewing conditions, and the amount of enlargement.

[tupp]

A standard value of CoC is often associated with each image format, but the most appropriate value depends on visual acuity, viewing conditions, and the amount of enlargement.

Well, that quote says it all (except for the fact that circle-of-confusion and depth-of-field are actually two different {but related} properties).

Nowhere in that quote is resolution mentioned.

Image format is mentioned as "often associated" with circle-of-confusion values, but the quote states that the most appropriate basis of circle-of-confusion is visual acuity. Visual acuity is not resolution.

If we were to base depth-of-field on resolution, we would encounter all kinds of silly, varying DOF ratings of the same optical system, which would change with each film stock/sensor and with the whim of any person viewing the captured image who decides to manipulate it long after it has been captured.