Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

--
Adam

"ARW" wrote in message
...
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

Quite possibly. Philips Hue bulbs seem to be remarkably constant, and I have
a desk lamp with several banks of LEDs which is fine except on the very
dimmest setting when I imagine there is no overlap between one bank and
another. Not that I use them for filming, but being curious, I investigated
with my mobile phone, my compact camera and my SLR camera, each on video
setting.

A lot depends on the shutter speed that that camera uses for each frame.
Proper camcorders tend to default to the maximum exposure time (1/25 second)
which gives smoother motion at the expense of blurred movement. GoPro type
cameras tend to use the shortest shutter speed that the light level will
allow, to give sharp frames in case you want to analyse frame by frame, but
this leads to disturbing artefacts on motion - eg aircraft propellers that
have disembodied blades. A short shutter speed is more likely to give
venetian blind type flickering with LEDs.

I remember once shooting in a large branch of Boots and the fluorescent
lights on the ceiling seemed to strobe in waves it was very weird at the
time. As I gradually lost my sight I started to notice this effect with my
eyes as well so it probably has to do with exposure etc.
Brian

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"NY" wrote in message
...
"ARW" wrote in message
...
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

Quite possibly. Philips Hue bulbs seem to be remarkably constant, and I
have a desk lamp with several banks of LEDs which is fine except on the
very dimmest setting when I imagine there is no overlap between one bank
and another. Not that I use them for filming, but being curious, I
investigated with my mobile phone, my compact camera and my SLR camera,
each on video setting.

A lot depends on the shutter speed that that camera uses for each frame.
Proper camcorders tend to default to the maximum exposure time (1/25
second) which gives smoother motion at the expense of blurred movement.
GoPro type cameras tend to use the shortest shutter speed that the light
level will allow, to give sharp frames in case you want to analyse frame
by frame, but this leads to disturbing artefacts on motion - eg aircraft
propellers that have disembodied blades. A short shutter speed is more
likely to give venetian blind type flickering with LEDs.

"Brian Gaff" wrote in message
...
I remember once shooting in a large branch of Boots and the fluorescent
lights on the ceiling seemed to strobe in waves it was very weird at the
time. As I gradually lost my sight I started to notice this effect with my
eyes as well so it probably has to do with exposure etc.

Fluorescents, if they are nearly but not quite in phase with the camera (eg
constant 25 fps camera, but mains at one extreme of the other - 49.5 or 50.5
Hz) produce weird effects because they produce two different lights: there
is a blueish light with very short persistence from the gas discharge and a
yellowish light with a longer persistence from the phosphor coating.
Together they produce a white light (for some value of white ranging from
warm white to daylight). But the strobing between the two allows you to see
the blue light fading in and out which means the flicker varies in colour as
well as brightness.

I saw the same effect with the blades of a desk fan, illuminated by
fluorescent desk lamp - at some fan speeds there was a sharp blue image and
a more blurred yellow ghost image alongside.


I'm always surprised that intermittent short-persistence lights are used for
filming, because of the problem with strobing. There is a scene in the film
The Krays where one of the twins is in a boxing ring at a fairground. The
sequence is shown in slow motion and the flicker of the mains-frequency
filming lights is very intrusive.

ARW wrote

Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

Yep, its possible. The higher power leds are usually pulsed, not continuous.

But some are pulsed at quite a high frequency.

NY wrote
ARW wrote

Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

Quite possibly. Philips Hue bulbs seem to be remarkably constant,

No they are not. Wag your finger past the
bulb and you can see the classic strobe finger.

and I have a desk lamp with several banks of LEDs which is fine
except on the very dimmest setting when I imagine there is no
overlap between one bank and another. Not that I use them for
filming, but being curious, I investigated with my mobile phone,
my compact camera and my SLR camera, each on video setting.

A lot depends on the shutter speed that that camera uses for each frame.
Proper camcorders tend to default to the maximum exposure time (1/25
second) which gives smoother motion at the expense of blurred movement.
GoPro type cameras tend to use the shortest shutter speed that the light
level will allow, to give sharp frames in case you want to analyse frame
by frame, but this leads to disturbing artefacts on motion - eg aircraft
propellers that have disembodied blades. A short shutter speed is
more likely to give venetian blind type flickering with LEDs.

Unlikely most surveillance cameras use a high frame rate.

On Wed, 21 Aug 2019 08:36:55 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

Quite possibly. Philips Hue bulbs seem to be remarkably constant,

No they are not. Wag your finger past the
bulb and you can see the classic strobe finger.

You can shove your finger together with your Philips Hue bulbs up yours,
senile asshole!

--
"Anonymous" to trolling senile Rot Speed:
"You can **** off as you know less than pig **** you sad
little ignorant ****."
MID:

On 20/08/2019 23:18, Rod Speed wrote:
ARW wrote

Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

Yep, its possible. The higher power leds are usually pulsed, not
continuous.

But some are pulsed at quite a high frequency.

That may also be modulated at 100Hz.

On Wed, 21 Aug 2019 08:18:42 +1000, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:


And any chance it could mess up any filming due to strobe effects?

Yep, its possible.

NOTHING could possibly be as messed up as you trolling senile asshole! BG

--
pamela about Rot Speed:
"His off the cuff expertise demonstrates how little he knows..."
MID:

On 20/08/2019 18:47, ARW wrote:
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?


Isn't the HQI a discharge tube, so no temporal filtering from a
phosphor? In which case they will be similar from a strobing effect.

If anything the LED might provide a more constant colour temperature
over the mains 1/2 cycle.

Is 3 phase available?

Brian Gaff wrote:

in a large branch of Boots and the fluorescent
lights on the ceiling seemed to strobe in waves it was very weird at the
time. As I gradually lost my sight I started to

banks of tubes split over a three-phase supply? or with lead-lag ballasts?

In article ,
ARW wrote:
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

Most modern pro video cameras can alter the 'shutter speed' to prevent
strobing.

--
*You know you're a redneck if your home has wheels and your car doesn't.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andy Burns wrote:
Brian Gaff wrote:

in a large branch of Boots and the fluorescent lights on the ceiling
seemed to strobe in waves it was very weird at the time. As I
gradually lost my sight I started to

banks of tubes split over a three-phase supply? or with lead-lag
ballasts?

Using three phase mains speed florries was the way to avoid strobing with
older TV cameras. Was the standard lighting rig for boxing matches.

--
*Never miss a good chance to shut up.*

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman wrote:

Using three phase mains speed florries was the way to avoid strobing with
older TV cameras.

If tubes from each phase were interspersed I can see how it would even
out, but if large sections of a large shop floor were on different
phases, I can see how it might annoy you out of the corner of your eye.

On Tuesday, 20 August 2019 18:47:12 UTC+1, ARW wrote:
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

Strobing can occur, but less so than discharge lamps on iron ballasts.

1. Low power LEDs often use a capacitor ballast giving 100Hz strobing. You're unlikely to be using those to get your 240w, unless it's a large array of low power things not intended for filming.
2. Most others use electronic PSUs operating at at least 10kHz, usually far higher - those aren't a problem if the reservoir caps are big enough to ensure no 100Hz flicker, which is not consistently the case.
3. Then there are cost cutting lights that use no reservoir cap, those flicker heavily at 100Hz.

If you do get 100Hz flicker with the 2nd type, feeding them all from a bridge rectifier & big reservoir cap will more or less eliminate it. I've no idea what the 18th has to say about 330v dc feeds though, which is what you get from such a supply. And all warranties are void. And some lamp types aren't ok with it.


NT

On 20/08/2019 23:57, Fredxx wrote:
On 20/08/2019 23:18, Rod Speed wrote:
ARW wrote

Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

Yep, its possible. The higher power leds are usually pulsed, not
continuous.

But some are pulsed at quite a high frequency.

That may also be modulated at 100Hz.



MS refitted all their stores with energy-saving florries
a couple of decade ago, and I noticed because they gave me
a nasty headache if I spent to much time in one.

On 21/08/2019 11:14, Dave Plowman (News) wrote:
In article ,
ARW wrote:
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

Most modern pro video cameras can alter the 'shutter speed' to prevent
strobing.


And I have noticed that the credits at the end of many programmes
now mention someone with the job title 'colourist' or similar.

I suppose these are the people who fiddle with the colours and
sometimes the effect is horrible. I am thinking of the infamous
Countryfile program when they were at the feeding event of
Red Kites in Wales. Someone in the post-production room made the
birds have the most garishly abnormal colour imaginable.

On 21/08/2019 00:04, Fredxx wrote:
On 20/08/2019 18:47, ARW wrote:
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?


Isn't the HQI a discharge tube, so no temporal filtering from a
phosphor? In which case they will be similar from a strobing effect.


Depending on the sophistication of the LED driver (and for that matter
the ballast in the HQI fitting). Both could have high frequency drivers.

If anything the LED might provide a more constant colour temperature
over the mains 1/2 cycle.

It will likely be a different emission spectra either way.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Warning shot over the pharmacist's head?

"Brian Gaff" Wrote in message:
I remember once shooting in a large branch of Boots and the fluorescent
lights on the ceiling seemed to strobe in waves it was very weird at the
time. As I gradually lost my sight I started to notice this effect with my
eyes as well so it probably has to do with exposure etc.
Brian



--
Jim K


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On 21/08/2019 11:50, John Rumm wrote:
On 21/08/2019 00:04, Fredxx wrote:
On 20/08/2019 18:47, ARW wrote:
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?


Isn't the HQI a discharge tube, so no temporal filtering from a
phosphor? In which case they will be similar from a strobing effect.


Depending on the sophistication of the LED driver (and for that matter
the ballast in the HQI fitting). Both could have high frequency drivers.

Even high frequency drivers tend to have limited smoothing and give
discontinuous light in keeping with the mains cycle.

If anything the LED might provide a more constant colour temperature
over the mains 1/2 cycle.

It will likely be a different emission spectra either way.

You're likely right, just reminded myself that LEDs use phosphors to
provide the appropriate colour temperature. Those phosphors will have
differing decay times.

On 21/08/2019 20:15, Fredxx wrote:
Even high frequency drivers tend to have limited smoothing and give
discontinuous light in keeping with the mains cycle.

Why not build a 230VDC power supply then?



--
If you tell a lie big enough and keep repeating it, people will
eventually come to believe it. The lie can be maintained only for such
time as the State can shield the people from the political, economic
and/or military consequences of the lie. It thus becomes vitally
important for the State to use all of its powers to repress dissent, for
the truth is the mortal enemy of the lie, and thus by extension, the
truth is the greatest enemy of the State.

Joseph Goebbels

On Wednesday, 21 August 2019 16:04:33 UTC+1, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:
On Tuesday, 20 August 2019 18:47:12 UTC+1, ARW wrote:
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

--
Adam

Not wuite the same but I was watching TV one night and ther ewas a car driving down a road with the headlights on and they were obviously flashing I'd say at around 10Hz it was one of those high end sports cars.

LED headlights. And probably news footage. Often shot by those with little
or no training.

So you need training in order to change reality, wow what news is that.

On Thursday, 22 August 2019 06:42:03 UTC+1, The Natural Philosopher wrote:
On 21/08/2019 20:15, Fredxx wrote:
Even high frequency drivers tend to have limited smoothing and give
discontinuous light in keeping with the mains cycle.

Why not build a 230VDC power supply then?

It;s all about power factors adn in tensities and cooling.
As LEDs are very suseptable to heat and run more efficintly at their brightest it;s better to just flash them off and on rathe rthan try to maintain a high brightness. This principle was used in the first radar systems to bleep and allow the valves to not burn out.

In article ,
whisky-dave wrote:
On Wednesday, 21 August 2019 16:04:33 UTC+1, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:
On Tuesday, 20 August 2019 18:47:12 UTC+1, ARW wrote:
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

--
Adam

Not wuite the same but I was watching TV one night and ther ewas a
car driving down a road with the headlights on and they were
obviously flashing I'd say at around 10Hz it was one of those high
end sports cars.

LED headlights. And probably news footage. Often shot by those with
little or no training.

So you need training in order to change reality, wow what news is that.

You certainly need some training about camera technology.


--
*On the seventh day He brewed beer *

Dave Plowman London SW
To e-mail, change noise into sound.

On Thursday, 22 August 2019 11:27:40 UTC+1, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:
On Wednesday, 21 August 2019 16:04:33 UTC+1, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:
On Tuesday, 20 August 2019 18:47:12 UTC+1, ARW wrote:
Swapping 1000W HQI fittings for 240W LEDs.

And any chance it could mess up any filming due to strobe effects?

--
Adam

Not wuite the same but I was watching TV one night and ther ewas a
car driving down a road with the headlights on and they were
obviously flashing I'd say at around 10Hz it was one of those high
end sports cars.

LED headlights. And probably news footage. Often shot by those with
little or no training.

So you need training in order to change reality, wow what news is that.

You certainly need some training about camera technology.

I doubt that, I think its you that'd need training.

On Thursday, 22 August 2019 11:16:11 UTC+1, whisky-dave wrote:
On Thursday, 22 August 2019 06:42:03 UTC+1, The Natural Philosopher wrote:
On 21/08/2019 20:15, Fredxx wrote:
Even high frequency drivers tend to have limited smoothing and give
discontinuous light in keeping with the mains cycle.

Why not build a 230VDC power supply then?

It;s all about power factors adn in tensities and cooling.
As LEDs are very suseptable to heat and run more efficintly at their brightest it;s better to just flash them off and on rathe rthan try to maintain a high brightness. This principle was used in the first radar systems to bleep and allow the valves to not burn out.

Do you ever stop bull****ting?

On Thursday, 22 August 2019 20:36:01 UTC+1, wrote:
On Thursday, 22 August 2019 11:16:11 UTC+1, whisky-dave wrote:
On Thursday, 22 August 2019 06:42:03 UTC+1, The Natural Philosopher wrote:
On 21/08/2019 20:15, Fredxx wrote:
Even high frequency drivers tend to have limited smoothing and give
discontinuous light in keeping with the mains cycle.

Why not build a 230VDC power supply then?

It;s all about power factors adn in tensities and cooling.
As LEDs are very suseptable to heat and run more efficintly at their brightest it;s better to just flash them off and on rathe rthan try to maintain a high brightness. This principle was used in the first radar systems to bleep and allow the valves to not burn out.

Do you ever stop bull****ting?

It's not BS look it up get an education.

On Friday, 23 August 2019 11:28:13 UTC+1, whisky-dave wrote:
On Thursday, 22 August 2019 20:36:01 UTC+1, tabby wrote:
On Thursday, 22 August 2019 11:16:11 UTC+1, whisky-dave wrote:
On Thursday, 22 August 2019 06:42:03 UTC+1, The Natural Philosopher wrote:
On 21/08/2019 20:15, Fredxx wrote:
Even high frequency drivers tend to have limited smoothing and give
discontinuous light in keeping with the mains cycle.

Why not build a 230VDC power supply then?

It;s all about power factors adn in tensities and cooling.
As LEDs are very suseptable to heat and run more efficintly at their brightest it;s better to just flash them off and on rathe rthan try to maintain a high brightness. This principle was used in the first radar systems to bleep and allow the valves to not burn out.

Do you ever stop bull****ting?

It's not BS look it up get an education.

lol