Question about WB setting for time-lapsed photography

[dfx]

The eye only refreshes about 30 times a second.

I've heard that before, but that's nonsense. The human eye doesn't have a refresh rate.

 

[flareside]

I've heard that before, but that's nonsense. The human eye doesn't have a refresh rate.

Yes, that is rather simplistic terminology (the comment actually dates back to the 1970s) but however you want to state it, the human eye has a limit to how fast it can collect and process data. The best example is the blur of a spinning propeller. The blur does not physically exist, the eye creates it because it cannot keep up.

 

[dfx]

Yes, that is rather simplistic terminology (the comment actually dates back to the 1970s) but however you want to state it, the human eye has a limit to how fast it can collect and process data. The best example is the blur of a spinning propeller. The blur does not physically exist, the eye creates it because it cannot keep up.

Yes, but that doesn't mean that it's impossible to see anything that happens faster than 30 fps (33.3 ms per frame). If you look at a light that flickers on and off at 30 fps, then yeah, you'll see it as a steady glowing light. But if you look at something dark which then emits a flash of light of only 1 ms duration, then you will be able to see that, even though that's well below the 30 fps threshold. It all depends on what you're looking at.

 

[flareside]

Yes, but that doesn't mean that it's impossible to see anything that happens faster than 30 fps (33.3 ms per frame). If you look at a light that flickers on and off at 30 fps, then yeah, you'll see it as a steady glowing light. But if you look at something dark which then emits a flash of light of only 1 ms duration, then you will be able to see that, even though that's well below the 30 fps threshold. It all depends on what you're looking at.

Nowhere did I state that you can't see anything that lasts less than 1/30th of a second, merely that the receptors in the eye start a new image, i.e. "refresh" roughly every 1/30th of a second and excess information collected in that time frame merely results in a blur. So by using your own example of a light that flickers at 30 fps is seen as a steady light, would a light that flickers at 60 fps be any different? Would you see any of the additional flashes? At 15 fps you would see an obvious flicker but there is no noticeable difference between 60 and 30 fps. Now transfer that logic back to 60 fps video.

And as far as whether "refresh" is the appropriate terminology, take the example of the flash bulb that fires in your field of vision. The dark spot stays in your vision until all the little receptors refresh themselves. For a significant burn, it can take several minutes. For normal light levels however, it happens roughly 30 times per second. The original comment came long before the digital revolution and while the digital revolution has perverted the term somewhat, if you go back to the dictionary version, all refresh means is to renew. It has nothing to do with video re-scanning and nowhere does it state that it is done in rows and columns as in the digital sense.

 

[dfx]

Nowhere did I state that you can't see anything that lasts less than 1/30th of a second, merely that the receptors in the eye start a new image, i.e. "refresh" roughly every 1/30th of a second and excess information collected in that time frame merely results in a blur. So by using your own example of a light that flickers at 30 fps is seen as a steady light, would a light that flickers at 60 fps be any different? Would you see any of the additional flashes? At 15 fps you would see an obvious flicker but there is no noticeable difference between 60 and 30 fps. Now transfer that logic back to 60 fps video.

And as far as whether "refresh" is the appropriate terminology, take the example of the flash bulb that fires in your field of vision. The dark spot stays in your vision until all the little receptors refresh themselves. For a significant burn, it can take several minutes. For normal light levels however, it happens roughly 30 times per second. The original comment came long before the digital revolution and while the digital revolution has perverted the term somewhat, if you go back to the dictionary version, all refresh means is to renew. It has nothing to do with video re-scanning and nowhere does it state that it is done in rows and columns as in the digital sense.

A decent description of persistence of vision. But that's only one part of the equation. Another part is motion and the fact that your eye can follow an object's motion. This allows you to make out details that otherwise you couldn't see with a fixed gaze. Imagine a very shaky video. With a low frame rate, the shake is likely to blur out each individual frame in the video. Thus, no details are left to be seen in the video, no matter how hard you try, everything is blurry. But with a higher frame rate, each frame will be sharper and will have more detail. When viewing it, your eyes can compensate for the shake and the image will be clearer. This becomes even easier if it's possible to predict the motion. Going back to your spinning propeller example, quickly moving your eyes e.g. left to right will allow you to see individual blades of the propeller, if only for the fraction of a second. But if the blades are already blurred out on video because the frame rate was too low, then you can't.

 

[EL Pistoffo]

It's funny how a thread can often go off track.........LOL