Fluoro Light is more intense than North window. True / False

[Garry H (Cut Nut)]

Sergey asked this question last week.

Which is more intense and brighter when you look at it directly - the light from a Fluorescent celing light (1, 2 or 4 lamps is the same ''intensity''), or cloudy day daylight from a North facing window (or South in the Southern hemisphere)?

 

[asblackrock]

No doubt about this one Garry - window wins, as long as you are not talking about late dusk.

 

[diagem]

Garry, I would imagine that ceiling would be brighter that cloudy North light....

I think I would trust flouro light on my judgement before northern light on a cloudy day. that assumption is based on my sole experience only.

What is the right answer??

 

[strmrdr]

Date: 7/24/2005 5:13:20 AM
Author:Garry H (Cut Nut)
Sergey asked this question last week.


Which is more intense and brighter when you look at it directly - the light from a Fluorescent ceiling light (1, 2 or 4 lamps is the same 'intensity'), or cloudy day daylight from a North facing window (or South in the Southern hemisphere)?

Too many variables undefined does not compute :}
How high is the ceiling and how tall is the person.
Latitude? cloud thickness? time of year? time of day? solar storms? which cycle is the sun in?
1/R2 makes a huge difference over relatively small changes in distance.
Also looking directly at it is not a good measure of brightness or intensity because its relative based on contrast.
A Fluorescent ceiling light on a black ceiling would look brighter than the same light on a white one.

 

[Garry H (Cut Nut)]

Say the light is 2m (6ft) above the diamond viewing position or a desk / table.
Say it is between 9am and 3am one a 12 hour sun day (at solstice spring or fall).

Fopr this experiment contrast is irrelevant

 

[strmrdr]

I would have to say probably true just from thinking back from what I have observed.
There are so many variables I dont know if a definitive answer is possible.

The angle of the window to the sky and the angle of the person/diamond to the window the wattage of the tubes are other variables.
The more I think about it the more variables come into play.

 

[Garry H (Cut Nut)]

C''mon Storm
play
the penalty 4 loosing is not Siberia

 

[strmrdr]

true

 

[Garry H (Cut Nut)]

Clue
Use a spoon

 

[belle]

i have discovered that my absolute favorite diamond viewing condition is filtered cloudy daylight, so i will go with the cloudy daylight for my answer.

 

[Garry H (Cut Nut)]

I would prefer you compare the window light in the middle of the room to a fluoro light directly above the diamond Belle

Like this:

 

[EZ]

There do seem to be a list of variables. Are the windows glazed or otherwise treated? I am guessing that an unglazed window will look more "intense." My mind experiment consists of imagining looking at each for 20 to 30 seconds and then looking at a dark wall. I think the after image of the window would appear stronger than the light.

 

[belle]

it''s sunshine for most of the year where i live so i don''t have much experience with cloudy days, however your picture reminded me of just how intense cloudy sunlight can be.

i am sticking with the window for my answer.

 

[Capitol Bill]

Garry,
Sounds like another one of your sticky wickets. Just look at the sly grins on the faces of that group (diamond dealers no doubt)

. One can't help but notice the idealscope and ASET-scope on the desk. If I were to guess, I'd say this little spoon experiment has something to do with which light is preferred as a backlight for such handheld devices. Am I close?

Without performing the spoon experiment for myself (no spoons in my desk at the moment), I'll take a gander and say [correction inserted hereafter] the north-facing light is more uniform, but the fluoros are more intense. If I'm right will you send me a prize?
Bill

 

[Hest88]

In my experience, the fluorescent light is more concentrated, thus more intense if I"m looking at it directly. Cloudy light is more diffuse so it''s not as bright.

 

[asblackrock]

Answer is easy to verify:

Try a light meter on the desk with the fluorescents on AT NIGHT (not even vague ight from closed blinds allowed), then try the on the desk on a cloudy day without the fluorescents on.

I am assuming the desk is next to the window and that the window is the average size usually used in a room and that blinds are open and that the window is clear glass and unobscured outside ie nothing "tricky" in the question.

You will be surprised just how much difference there is, even with full cloud cover.

 

[Garry H (Cut Nut)]

Well here is a close up of the spoon on the desk in Janak Mistry''s Surat office.
It clearlly shows in the reflection that the light from the window is much brighter.
I have jsut done the same on an overcast day here in wintery Melbourne at 11.00am - the fluoro light is duller, but a 60watt ordinary naked suspended Tungsten bulb is more intense than the light from a window - albeit that the tungsten globe appears even more yellow that the flouro light in the spoon refelction.

The quest raised by this issue concerns the idea that lighting intensity is sourced predominatley from the ceiling area. Princess and many other fancy cuys brightness may be as dependant on window light as on ceiling lights for example.

 

[strmrdr]

ah but the light reflected from the spoon would be affected by the wattage and number of bulbs which you said not to consider.
It cant be eliminated.

You also said which is brighter when you look at it which is different than which would reflect more light off a spoon.

 

[Garry H (Cut Nut)]

The globe is more intense (brighter) but has less light output.