Spinner strobing as a "Bird Strike Countermeasure"

Gig 601XL Builder writes:

Wrong, exactly backwards wrong. Rutger was correct.

The frame is a painted raster. The image is the complete set of visual data
for simultaneous assimilation.

On Mon, 03 Dec 2007 02:52:14 -0000,
(Robert Bonomi) wrote:

In article ,
Maxwell wrote:

"Roger (K8RI)" wrote in message
...
On Sun, 02 Dec 2007 22:09:30 -0000, Jim Logajan
wrote:

At cruise RPM that effect would be completely lost. There's not a
bird or human alive that can discern stroboscopic effects of more than
a couple hundred cycles let alone over a 1000. Most of us can't even
discern 60 cps.



"Mike Noel" wrote in message
...
True, but aren't we talking about 40 cps when the prop RPM is 2400?


Seems I have heard the 16 cps is all that is required for movies to appear
continuous. I think the human eye loosed it around 12 or 13. However, we
don't seen consciously either. Hence the reason an aircraft propeller will
appear to be revolving slowly backwards at times.

Visual perception is funny and complex.

black & white films were 16 frames/second.
Color films are 24 frames/second

U.S. TV is 60 fields/second, European is 50/second.
This is driven more by the need for phospors that 'decay' rapidly enough
to not produce 'blurred' motion than perception issues.

OTOH, A significant number of people can perceive 'flicker' in conventional-
tube fluorescent lamps. which is at 120 flickers/second.

I seriously doubt they can. I can discern the flicker in *some*
fluorescent lights, but I can not discern 120 cps on a strobe. I
think what they are seeing is the "sputter" of a cold lamp or a light
that isn't starting correctly. The flicker I see in those lamps is
considerably slower than 120 or even 60 cps.

First, for any flicker the phosphor has to be defective which means
the lamp is already defective so we can't expect it to be behaving
normally.

it would be interesting to see if those same people can discern even
60 cps in a strobe.

Also, the eye -- and brain -- 'notices' things that are too fleeting for
conscious identification. Google 'subliminal' advertizing -- IIRC, lab
tests showed that injected imagery with a duration of only a few milliseconds
had 'measurable' effects.

It's controversial, but has been called one of the greatest myths of
all time. It's generally accepted they are ineffective.
http://www.sciam.com/article.cfm?art...E19&sc=I100322
According to the Scientific American article they at best distract the
viewer.

Roger (K8RI)

Roger (K8RI) writes:

I seriously doubt they can. I can discern the flicker in *some*
fluorescent lights, but I can not discern 120 cps on a strobe. I
think what they are seeing is the "sputter" of a cold lamp or a light
that isn't starting correctly. The flicker I see in those lamps is
considerably slower than 120 or even 60 cps.

Peripheral vision is much more sensitive to flicker than central vision. Some
people will perceive an irritating flicker in a lamp or computer monitor each
time they turn away from it, and yet the flicker will disappear when they look
directly at it.

The perception is limited to the impression that the light is flickering; that
doesn't mean that they can count the individual flashes.

First, for any flicker the phosphor has to be defective ...

How can the phosphor be defective?

"Mxsmanic" wrote in message
...
Roger (K8RI) writes:

I seriously doubt they can. I can discern the flicker in *some*
fluorescent lights, but I can not discern 120 cps on a strobe. I
think what they are seeing is the "sputter" of a cold lamp or a light
that isn't starting correctly. The flicker I see in those lamps is
considerably slower than 120 or even 60 cps.

Peripheral vision is much more sensitive to flicker than central vision.
Some
people will perceive an irritating flicker in a lamp or computer monitor
each
time they turn away from it, and yet the flicker will disappear when they
look
directly at it.

The perception is limited to the impression that the light is flickering;
that
doesn't mean that they can count the individual flashes.

First, for any flicker the phosphor has to be defective ...

How can the phosphor be defective?

No, that's just a symptom of the electro shock therapy.

Mxsmanic wrote in
:

Roger (K8RI) writes:

I seriously doubt they can. I can discern the flicker in *some*
fluorescent lights, but I can not discern 120 cps on a strobe. I
think what they are seeing is the "sputter" of a cold lamp or a light
that isn't starting correctly. The flicker I see in those lamps is
considerably slower than 120 or even 60 cps.

Peripheral vision is much more sensitive to flicker than central
vision. Some people will perceive an irritating flicker in a lamp or
computer monitor each time they turn away from it,

A bit like looking at you.
Bertie

Maxwell writes:

Seems I have heard the 16 cps is all that is required for movies to appear
continuous.

Motion pictures use 24 ips, repeated once, giving 48 fps (24 images shown
twice each). The motion is smooth as long as the image isn't too bright,
large, or fast-moving. Sometimes a stroboscopic effect can be seen in the
latter cases. It can be hidden by allowing image elements to blur.

You can see this effect very clearly on TV (30 ips in the U.S.) when sporting
events are showing that have been recorded with high shutter rates in the
cameras. Each image is sharp and it's easy to see that a succession of
individual images is being shown on the screen, even at 30 ips.

I think the human eye loosed it around 12 or 13.

Higher than that. Twelve images per second tends to look noticeably jerky.

Hence the reason an aircraft propeller will
appear to be revolving slowly backwards at times.

Not when being observed directly. That only happens in movies and video due
to the interaction between the imaging rate and the rotation rate of the
propeller.

"Mxsmanic" wrote in message
...
Maxwell writes:

Seems I have heard the 16 cps is all that is required for movies to
appear
continuous.

Motion pictures use 24 ips, repeated once, giving 48 fps (24 images shown
twice each). The motion is smooth as long as the image isn't too bright,
large, or fast-moving. Sometimes a stroboscopic effect can be seen in the
latter cases. It can be hidden by allowing image elements to blur.

You can see this effect very clearly on TV (30 ips in the U.S.) when
sporting
events are showing that have been recorded with high shutter rates in the
cameras. Each image is sharp and it's easy to see that a succession of
individual images is being shown on the screen, even at 30 ips.

I think the human eye loosed it around 12 or 13.

Higher than that. Twelve images per second tends to look noticeably
jerky.

Hence the reason an aircraft propeller will
appear to be revolving slowly backwards at times.

Not when being observed directly. That only happens in movies and video
due
to the interaction between the imaging rate and the rotation rate of the
propeller.

Wrong again you clueless twit.

In article , says...


Hence the reason an aircraft propeller will
appear to be revolving slowly backwards at times.

Not when being observed directly. That only happens in movies and video
due
to the interaction between the imaging rate and the rotation rate of the
propeller.

Wrong again you clueless twit.



No, he is right this time.

"Airbus" wrote in message
...
In article , says...


Hence the reason an aircraft propeller will
appear to be revolving slowly backwards at times.

Not when being observed directly. That only happens in movies and video
due
to the interaction between the imaging rate and the rotation rate of the
propeller.

Wrong again you clueless twit.



No, he is right this time.

No he isn't.

In article , says...



"Airbus" wrote in message
...
In article , says...


Hence the reason an aircraft propeller will
appear to be revolving slowly backwards at times.

Not when being observed directly. That only happens in movies and video
due
to the interaction between the imaging rate and the rotation rate of the
propeller.

Wrong again you clueless twit.



No, he is right this time.

No he isn't.


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