Help me understand CFL watts

vigilante · Mar 5, 2015

I'm just curious, when looking at continuous lighting kits, they will usually come with CFL bulbs listed as 30 or 45 or 85 watts. But then the "entire" kit is listed at maybe 850 watts. Seems to me that two 85 watts bulbs equal 170 watts, not 850.

See here: Amazon.com StudioPRO 850W Photography Portrait Studio Continuous Lighting 7 6 Light Stand Two Light Black on White Umbrella Kit with Two 85W CFL Bulbs Photographic Lighting Umbrellas Camera Photo

Two 85 watt bulbs, equals 850 watts of light? What am I missing?

qleak · Mar 5, 2015

I think they may be listing the equivalent incandescent bulbs.

Each bulb has 5600 LM divide by 13 (typical LM/WATT for incandescent) and you get 430 W.

How to convert watts to lumens lm

edited to make come out closer to the supplier indicated

480sparky · Mar 5, 2015

The problem is a watt is a measurement of energy consumption, not light output.

How much light does your 1,200-watt hair dryer put out? Or you 1,000-watt microwave? Or a 1,500-watt toaster oven?

Derrel · Mar 5, 2015

The biggest problem with these new compact fluorescent light bulb + umbrella kits is that they are designed to get people to buy a very inferior solution, based upon good ad copy, and deception. I looked at the listing; it's two, 85-Watt CFL bulbs in holders, with umbrellas, and a couple cheap light stands, with the implication that this offers "850 Watt-equivalence"...but...equivalent to what? I do not see it stated that this is equivalent in output..it's implied.

But the lies....that CFL setups like this one are ideal for products and for people....uhhhh, NO, that's not true at all. Low-powered continuous light setups are in no way ideal for people.

Seriously, there is an entire sub-industry now that we have the internet; this sub-industry id devoted to ripping off people who have no idea of what they need, by using deceptive ad copy, and tricking people into believing what is being offered is legitimately good for actual uses. Save the money, and buy cheap FLASH setups if you want to do still photos, or photograph people.

vigilante · Mar 5, 2015

I had no intention of buying the kit

I just know that when I look at a lighting of any kind, it's almost impossible to compare them.
How much light does a full power flash produce? How does that compare to other bulbs? I would like to know the answer to a question like this:
"I have two XYZ flashes set to 1/64, if I use two 85watt CFLs instead, this is M times less light in the scene..."

What does "more light" and "less light" even mean?

I don't have a meter to run tests, but I figured there must be some kind of way to compare manufacture specs in a reasonable way.

480sparky · Mar 5, 2015

Speedlights ('flashes') are rated in guide numbers.

I'm not even sure it's possible to convert that to CFL watts, or even lumens.

KmH · Mar 5, 2015

Yep. There is no direct conversion factor fro a flash unit guide number to watts or any other unit of energy consumption or production.
There isn't any consistency with GN either because GN can be stated relative to different flash zoom head focal length settings and ambient temperature values.

A person just has to do a lot of research and get some experience before they start to get a feel for what the numbers are actually saying.

qleak · Mar 5, 2015

vigilante said:
"I have two XYZ flashes set to 1/64, if I use two 85watt CFLs instead, this is M times less light in the scene..."

I can't see myself mixing a flash with a continuous light source unless it was ambient. So i don't think this comparison is that important.

Mater of fact, i wouldn't buy a continuous light source specifically for still photography.

vigilante · Mar 5, 2015

Regardless, plenty of people do still photography (objects, products) with continuous light. It's probably the most common type of how-to video I've seen on Youtube for example.
As long as one can slow the shutter a pinch or maybe even use a lightbox, their results are great.

I personally am using flashes, I have two flashes now but am still working out how to use them properly and at what angles to place them and how to bounce the light around with cards etc etc.
Flashes do require some extra work, planning, setup, and some trial and error, that is no joke!

qleak · Mar 5, 2015

vigilante said:
Regardless, plenty of people do still photography (objects, products) with continuous light. It's probably the most common type of how-to video I've seen on Youtube for example.

The key word in that is video. You need continuous light for video.

I doubt many people try to slow the shutter with continuous light. i think you mean speed up the shutter.

To help with placement studio strobes have modeling lights, some with proportional power.

astroNikon · Mar 5, 2015

vigilante said:
Regardless, plenty of people do still photography (objects, products) with continuous light. It's probably the most common type of how-to video I've seen on Youtube for example.
As long as one can slow the shutter a pinch or maybe even use a lightbox, their results are great.

I personally am using flashes, I have two flashes now but am still working out how to use them properly and at what angles to place them and how to bounce the light around with cards etc etc.
Flashes do require some extra work, planning, setup, and some trial and error, that is no joke!

save yourself alot of time and figuring things out. Buy this book ==> Light Science and Magic An Introduction to Photographic Lighting Fil Hunter Steven Biver Paul Fuqua 9780240812250 Amazon.com Books

It will save you alot of time.

astroNikon · Mar 5, 2015

Continuous lighting is fine, especially if you do video too (except for people photography or anything that moves). Can't use flash with video.
But rather than CFL, why don't you look at those snazzy LED lights instead. They're used in video too. ==> LED Buy or Learn at Adorama

But if you get into people photography, flash/ strobes is the way to go.
With a good strobe it has a modeling light, so you can get a good idea of the angles and shadows and stuff before you take a shot.

malibushooter · Mar 5, 2015

If you are serious about video lighting for people and or products : check out the one system that 90% of HOLLYWOOD USES. KINOFLO

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malibushooter · Mar 5, 2015

The other 10% uses hmi

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vigilante · Mar 6, 2015

It just brings me back to the same question. How does a LED light kit measure in light output to an 85 "watt" CFL? How is one supposed to know what is what?

Assuming that we're still talking product photography, I happen to have 3 85 watt CFL lamps already, but they don't product enough light for product shots without me having to slow the shutter and use the tripod. In some cases I've had to place the lamp just a few inches away from the product.
With my flashes though, even on low power, I can shoot at 1/200th with ISO100 and not even need a tripod.

The main difference I've seen between the two is that the flashes produce much more natural lighting, but I have to be very careful about shadows and hot spots when using flashes. Sometimes they create much more dramatic lighting issues across the product compared to using lamps. That is even when using soft boxes on the flashes.