Like a CANDLE in the wind...

Archiver

I have a question pertaining to light. I have some photocells from Radio Shack
that I'm using to sense light. Specifically, the BS1 takes a "snapshot" of the
light surrounding it and saves the data as "normal light condition", then, if
any change occurs in the light, alarm! Now, my question is this: You display
temperature in F and C, but what about light? I know there is a unit called the
"candle", but I don't know how it is measured. I need to turn the resistance
into the candle unit, but I know nothing about it. How do I figure candles?
Someone please help!!!


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Archiver

Hi!
The candle is an unit for brightness of a light source. One of the units
used for illumination (what you get with a photocell) is "Lux". .Also,
foot-candles is used in the imperial systems of units. Candles and
foot-candles (and Luxes) are related by the distance from the light source.
If you need to calibrate your system, the best way (short of buying one),
is to ask a a friend to lend you a mesuring device. They are used in
professional or serious amateur photography and cinema.

Hope this helps, Regards, Jose Luis

At 23:40 11/10/2001 -0500, you wrote:
>I have a question pertaining to light. I have some photocells from Radio
>Shack that I'm using to sense light. Specifically, the BS1 takes a
>"snapshot" of the light surrounding it and saves the data as "normal light
>condition", then, if any change occurs in the light, alarm! Now, my
>question is this: You display temperature in F and C, but what about
>light? I know there is a unit called the "candle", but I don't know how it
>is measured. I need to turn the resistance into the candle unit, but I
>know nothing about it. How do I figure candles? Someone please help!!!
>
>
>[noparse][[/noparse]Non-text portions of this message have been removed]
>
>
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[noparse][[/noparse]Non-text portions of this message have been removed]

Archiver

Hi

Try downloading the earth measurements experiment #4
Dr. Allen does a great job of explaining light
measurements. The experiment also give a formula for
calculating lux !

Pat


--- Astro Fizzix <astro_fizzix@y...> wrote:
> I have a question pertaining to light. I have some
> photocells from Radio Shack that I'm using to sense
> light. Specifically, the BS1 takes a "snapshot" of
> the light surrounding it and saves the data as
> "normal light condition", then, if any change occurs
> in the light, alarm! Now, my question is this: You
> display temperature in F and C, but what about
> light? I know there is a unit called the "candle",
> but I don't know how it is measured. I need to turn
> the resistance into the candle unit, but I know
> nothing about it. How do I figure candles? Someone
> please help!!!
>
>
> [noparse][[/noparse]Non-text portions of this message have been
> removed]
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
> from the same email address that you subscribed.
> Text in the Subject and Body of the message will be
> ignored.
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>


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