Continous Light wattage/lumens

[c71clark]

For traditional hot lights, about how many watt's are suggested for a 1 or 2 person full body portrait? I know some of it is personal preference, but I am looking for a rule of thumb. Now, could you also convert that into lumen's?

I am looking to try a small kit in a portrait setting, and am having a hard time trying to figure out the baseline needs if I were to use fluorescent lights. Their watt rating isn't any good since the use so much less power. They do usually list the lumen's though, so to begin with, I will have to work with that.

Thanks for any help!

[davidseaton]

http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00LpR2

[Wilt]

There is no conversion of watts to lumens...You will see, on ordinary light bulb packages on store shelves, that different models of same-wattage bulbs each have a different output of light!

Watt is the consumption of electricity...lumens is the output of light. Somewhere in the middle is the conversion efficiency and how much energy is lost as heat, and how much is converted to light.

[Wilt]

One claim about photo fluorescent...
ALZO 1512-55 85 WATT - COLOR TEMP 5500K
Super Bright - 4800 Lumins @ 1m.
Equivalent to 3 ALZO 1069, or 2 ALZO 1146, or 300 watts tungsten.

[PacAce]

One claim about photo fluorescent...
ALZO 1512-55 85 WATT - COLOR TEMP 5500K
Super Bright - 4800 Lumins @ 1m.
Equivalent to 3 ALZO 1069, or 2 ALZO 1146, or 300 watts tungsten.
That would just under EV 11 or 1/60 @ f/5.6 @ ISO 100 or 1/250 @ f/2.8 @ ISO 100.

[c71clark]

This incompatibility and confusion is why I figured I would go at it like I do mazes... backward. If I knew the rule-of-thumb for tungsten wattage for a 1 or 2 person portrait, I could look up the lumens for that light setup, then match that lumen output to whatever wattage I would need for a fluorescent setup.


A 30 watt fluorescent bulb I am looking at puts out 1500 lumens. A 4-bulb, 30 watt each fluorescent head would put out about 6000 lumens.

A 250 watt tungsten flood puts out 6500 lumens.

Would it be reasonable to say that the meter reading from each of those 2 lights would be roughly equivalent? Bear in mind that the tungsten is bare bulb, but the fluorescent lights have a built-in diffuser by virtue of the way they are built.

[PacAce]

This incompatibility and confusion is why I figured I would go at it like I do mazes... backward. If I knew the rule-of-thumb for tungsten wattage for a 1 or 2 person portrait, I could look up the lumens for that light setup, then match that lumen output to whatever wattage I would need for a fluorescent setup.


A 30 watt fluorescent bulb I am looking at puts out 1500 lumens. A 4-bulb, 30 watt each fluorescent head would put out about 6000 lumens.

A 250 watt tungsten flood puts out 6500 lumens.

Would it be reasonable to say that the meter reading from each of those 2 lights would be roughly equivalent? Bear in mind that the tungsten is bare bulb, but the fluorescent lights have a built-in diffuser by virtue of the way they are built.

If you used an efficient reflector so that both the flood light and the fluorescent bulbs both illuminated the same area, then I would think that both bulbs would be roughly equivalent.

[c71clark]

I had my first fluorescent shoot last week, actually, my first continuous light shoot in a studio also, and learned something. You need a LOT of light to get to a decent f/stop. Out of several hundred pictures, the exposure was generally in the area of 1/30 at f/2.5 or a little less. I don't mind the apeture so much, as I enjoy controlling dof, but the shutter speed sucks. I have another one today, and I hope to see better results.

But I must say, I am really pleased with the process. Being able to SEE the effect of the light before pulling the trigger is really nice.

[Wilt]

I had my first fluorescent shoot last week, actually, my first continuous light shoot in a studio also, and learned something. You need a LOT of light to get to a decent f/stop. ... Being able to SEE the effect of the light before pulling the trigger is really nice.

You have just expressed the real reason why learning lighting with studio lights, and NOT speedlights, is so very helpful to the education process! Modelling lights in studio strobes gives the ability to see in advance, without the disadvantage of the slow shutter speeds, avoided by the flash tube.

[christyjo2]

i use continuous lighting and i love it