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500W incandescent equivalency to CFL

Gustavo Duenas , Apr 05, 2013; 05:00 p.m.

Hello there. I have this question that has been rounding my mind recently.
I have a set of lights for portraits and due the high prizes of electricity I'm really thinking about to change to energy saver bulbs but how can I look for an accurate equivalency between my actual lights 500W GE photobulb 3250K to the CFLs that are in the market for photography lighting. I've seen this 85W studio CFL lights of 5500K I've noted that on the paper these are very good but in the practice are they?
If someone can hand me some answers about if they are a good replacement or at least point me to a good replacement for my energy devouring incandescent photobulbs.

Thanks.

Gustavo Duenas
[Website Deleted]

Responses

Rodeo Joe , Apr 05, 2013; 05:56 p.m.

CFL lamps are about 4 times more efficient than incandescent filament bulbs. So an 85W CFL will give out around the same amount of light as a 350W tungsten lamp. But, that doesn't take into account the higher colour temperature of the CFL, and because it's a closer match to daylight it'll give a higher effective exposure to daylight-balanced film or a digital sensor. You'll probably find there's little difference in the actual exposure settings needed between an 85W CFL and a 500W/3200K tugsten lamp. Your studio will certainly be cooler and your portrait sitters feel more comfortable with CFLs.

Another (lower cost) alternative might be to swap to Tungsten-Halogen lamps. These are about 30% more efficient than standard tungsten bulbs, so a 350W T-H would give an almost identical output to a 500W "conventional" lightbulb. Some types now have a double glass envelope that overcomes the drawback of being sensitive to handling and finger grease.

Personally, though, I had my fill of hot lights many years ago and re-equipped with studio flash as soon as I could afford it. Never looked back.

William W , Apr 05, 2013; 09:12 p.m.

As already mentioned, I’d calculate about 3.5 to 4 times the effective output.

So the 85 CFL is around ‘equivalent of’ a 300~340wTungsten Light. If you do replace the bulbs I would use “x3 times the output” as your guide for purchase, as that is a conservative approach and will give you a buffer of more light, rather than you falling short and not having enough light.

Also, as mentioned, the difference in Colour Temperature equates to ‘about’ ⅓ Stop for Portraiture of a mildly sun-toned Caucasian Subject. That’s not much and for practical consideration, in a studio you’d be using a light meter for the exposures anyway: but the exposure difference is usually measurable - if you really want to do some A/B testing.

***

In response to your question:

“ . . . point me to a good replacement for my energy devouring incandescent photobulbs.”

I suggest you use Flash.

As your website indicates that you are essentially a Portrait Photographer AND also you have a clientele compromising children, Flash certainly has advantages over continuous lighting; not the least of which is more easily attaining a desirable shutter speed and or flash exposure time to arrest Subject Motion, whilst maintaining enough power for an adequate DoF at slower Film speeds or lower digital ISO.

Also, there is less (almost zero) Colour Temperature variance between Flash Heads, than continuous Lighting Bulbs, especially as they wear older.

WW
(For your future reference: Linking to you Business Website as part of your sign-off, is not allowed.)

Gustavo Duenas , Apr 05, 2013; 09:36 p.m.

Thanks William and Joe for your responses, yes I will definitely dig into the 85W Cfls, with probably one or two more lights . The flashes and probably the strobe flashes too looks like something to try too. Also about the link, I didn't know....sorry my bad...

[Website Deleted]

William W , Apr 05, 2013; 10:43 p.m.

. . . sorry - that was my bad, for not being specific enough to cover all possibilities:
I should have written "Signing-off with your website (or business name, etc), is not allowed"
You can list your business name, etc, at your Bio Page, (which you have already done).

WW

Craig Shearman , Apr 08, 2013; 12:33 p.m.

"due the high prizes of electricity"
If saving money on your electricity bill is your main motivation, I would reconsider.
Even at 500 watts, light bulbs simply don't account for that much of the household electric bill. Your bill gets driven up by things like central air, electric heat, electric stoves and ovens, portable heaters, a well (if you're not on municipal water), etc. I've swapped almost every light bulb in my house (regular bulbs, not photographic) to CFL and haven't noticed a penny of savings. Photographic bulbs are much higher wattage than household bulbs, but they are only on long enough for a photo session, not all day, day after day.

Craig Shearman , Apr 08, 2013; 01:15 p.m.

deleting accidental double post

Gareth Watkins , Apr 09, 2013; 06:20 a.m.

Craig makes a valid point on the small savings on the electricity bill. Also CFL lamps vary considerably in the quality of light they produce. You will pay a premium for good ones suitable for photography.

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