why would staying in 3K not be as sharp as 3K to 2K

[Kevin Halverson]

Joofa, you're using square waves which you know are not bandwidth limited.

Graeme

Great point...

even spectrally richer is an impulse event (though lacking in energy). I am not even sure how one would make an impulse event that could be used as a stimulus for a sampled optical system.

Could make for a really nerdy conversation topic...

I wonder who might fall into the category of participating in really nerdy conversation topics?

 

[Dj Joofa]

Great point...

Yes, it was a point well-taken by Graeme Nattress since Shannon sampling theorem only applied to band-limited signals and square wave is not band-limited. I wasn't very careful about it.

even spectrally richer is an impulse event (though lacking in energy). I am not even sure how one would make an impulse event that could be used as a stimulus for a sampled optical system.

Don't understand what you are saying here. However, firstly the concept of impulse as defined by engineers as delta function is not rigorous mathematically, and has certain problems. Therefore some mathematicians re-defined it so that it is sound. (Not that it changes anything in engineering terms though )

The mathematical answer:
================

Impulse is treated:

(1) as a functional (different from function)
(2) as a generalized function on the space of distributions

The engineering answer:
===============

I think it is sufficient to quantify something as an "impulse" if its shorter than the shortest time-constant of a system. I have to really think about it if that notion is well-defined but that is my top of head answer.

 

[Gordon JL]

If you're aiming for standard-def DVD, you could use a 720P mode or higher (2K, 3K, 1080P) and still get a great crisp sharp DVD. Depth of field will be shallower when you use the larger frame size, of course, because the wider field of view means you have to get closer.

Barry, are you implying that by shooting in 3K, a larger frame size than say native 1080p, it will yield shallower DOF?

 

[Barry Green]

Barry, are you implying that by shooting in 3K, a larger frame size than say native 1080p, it will yield shallower DOF?

Yes, because for any equivalent zoom setting the larger frame size will yield a larger field of view. To get equivalent framing, you'll have to either zoom in more, or move closer. Doing either of those will cause the DOF to be shallower.