Pros and cons of flash vs constant lighting and more ?

[unpopular]

and this energy can be measured in watt/time.

I know you know this - it's watts times time, not watts divided by time.

yeah. I just didn't want to say watt/second because I didn't want to limit what I was saying to one second. When we're talking about exposure end of the equation, time is the variable and the wattage is the constant.

The "/" represents "per" not "divided by".

 

[fjrabon]

and this energy can be measured in watt/time.

I know you know this - it's watts times time, not watts divided by time.

yeah. I just didn't want to say watt/second because I didn't want to limit what I was saying to one second. When we're talking about exposure end of the equation, time is the variable and the wattage is the constant.

The "/" represents "per" not "divided by".

per means divided by.

 

[unpopular]

piss, you're right. now i am confused. Should it be time per watt then?

 

[Helen B]

No, it should be watts (symbol W) times seconds (symbol s), or watt·seconds or W·s also known as joules (symbol J).

 

[unpopular]

but wouldn't seconds per watt be the same as watts * second?

 

[Helen B]

'Fraid not. If you are having difficulty seeing it, think of it in joules (watt = joules/second).

seconds per watt = s/W = s/(J/s) = s²/J or seconds squared per joule (a unit of weirdness or insanity)

watt·seconds = W·s = (J/s)· s = J (joules ie energy, not to be confused with the Jools-Holland, which is a cute unit of pure music)

 

[unpopular]

(a unit of weirdness or insanity)

LOL. Helen, you win every time!

 

[tomso]

From an engineering/physics standpoint, Watts are simply a measure of the power required to reach a desired light output. If light x had a light output of 1000 lumens and a watt measurement of 50 W, it means that it required 50 Joules per second to power light x to the theoretical full 1000 lumens. If light y had a light output of 500 lumens and a watt measurement of 100 W, it means that it required 100 Joules per second to power light y to the theoretical full 500 lumens, which is still only half as bright as light x. Upping the power input to either light would likely blow the resistor (which is what causes the illumination).

A camera's sensor varies the amount of light recorded because of the time it takes the light to reach the sensor through the lens (this is where you get the inverse square law from). A more intense light source means there will be more photons traveling from the light source through your lens and thus you have don't have to have the shutter open as long. A light twice as bright? Leave the shutter open 1/4 of the time required for the standard light at the same distance. Watts are, unfortunately, a terrible way to measure light output. Unless you make the silly assumption that all lights have the same lumen output, in which case wattage may be an accurate estimate.

 

[Helen B]

A camera's sensor varies the amount of light recorded because of the time it takes the light to reach the sensor through the lens (this is where you get the inverse square law from).

Is it really?

A more intense light source means there will be more photons traveling from the light source through your lens and thus you have don't have to have the shutter open as long. A light twice as bright? Leave the shutter open 1/4 of the time required for the standard light at the same distance.

Twice as bright: half the shutter speed, not a quarter.

 

[fjrabon]

A camera's sensor varies the amount of light recorded because of the time it takes the light to reach the sensor through the lens (this is where you get the inverse square law from).

Is it really?

A more intense light source means there will be more photons traveling from the light source through your lens and thus you have don't have to have the shutter open as long. A light twice as bright? Leave the shutter open 1/4 of the time required for the standard light at the same distance.

Twice as bright: half the shutter speed, not a quarter.

Yeah, the inverse square law has to do with distance of the light source, not time.

 

[tomso]

A camera's sensor varies the amount of light recorded because of the time it takes the light to reach the sensor through the lens (this is where you get the inverse square law from).

Is it really?

A more intense light source means there will be more photons traveling from the light source through your lens and thus you have don't have to have the shutter open as long. A light twice as bright? Leave the shutter open 1/4 of the time required for the standard light at the same distance.

Twice as bright: half the shutter speed, not a quarter.

Yeah, the inverse square law has to do with distance of the light source, not time.

My mistake. I was thinking along the lines of speed of light being constant, so distance and time are proportional in a 1:1 ratio, so that must mean they can both be described using the inverse square law (really though that one through...). Electromagnetism was never one of my strong points.

 

[Derrel]

Hey--I JUST got back from voting and the grocery store afterwards: I bought a whole, baked chicken from a hot case that was lighted by three, 150-Watt heat lamps inside a five foot-long enclosure....so my questions are simple ones.

1) How hot is my chicken supposed to be?

2) How long do I have to eat the chicken until it becomes cold ?

3) Should I cut the chicken into pieces, or like is mentioned on The Big Bang Theory,should I eat the chicken with my bare hands while leaning over the kitchen sink??

Oh...I also bought some freaking coffee while at the grocery store!!!!

 

[unpopular]

it really depends on the quantum yield of the chicken. Higher quantum yield is typically better for the in-the-hand-hand method.