Using compact flourescent lamps for lighting

I've noticed a picture of some studio lighting using compact flourescent
lamps. I've seen US websites selling lamps stating they are ideal for
digital photography. I'vealso seen 6500K daylight balanced lamps
advertised in the UK, but no comment on photography.

Are any of these any use with film?

Pete

 

Yes. The daylight-balanced CF bulbs work well with regular print film
and even with slide film. Perhaps they don't work quite as well as
the expensive photography-ready continuous-spectrum fluorescent bulbs,
but they certainly are a lot cheaper!

The "soft white" CF bulbs appear somewhat yellow, as you would expect,
but not ugly green like old-style long-bulb fluorescents.

 

For the most part all fluorescent lamps are problems for really good
color. Not just for film or digital, but also for your own eyes. That is
why most meat displays in markets don't use them. However they are getting
better and the best ones are not too bad. Film and digital will react
somewhat different, but not necessary better or worse.

I suggest you give the ones of your choice a try and see if it works for
what you want.

 

It is becoming a serious lighting option for small _digital_ studios. Much
easier to work with than strobes, can be ganged up cheaply (I saw one product
with 9 flourescents in a gang behind a softbox...). As they are somewhat cooler
than incandescent you don't get nearly as much heat. The color temp is well up
into the fabled daylight range ...but even if not, most digital cameras have a
color temp setting.

Another lighting option is bright LED's which come in at over 5500K and are also
ganged up... probably great for a variety of situations ... (no idea on cost,
etc.) http://www.led-shop24.de/assets/own/5mm_white.pdf and can be ganged up
into standard socket fixtures. (Can't find the link right now).

The big caveat with all the above is that even with a lot of lighting you'll be
working with fairly slow shutter speeds which might not meet some needs.

Cheers,
Alan.



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[SNIP]

Yes but...

They aren't a continuous spectrum source (even Kino-Flo aren't), unlike
Tungsten, flash, or, of course, daylight. Thus they don't, in the true
sense, even have a colour temperature: rather they produce an 'overall
effect' that is equivalent to a given colour temperature by having a series
of emission lines that mix to produce a good approximation of 'daylight
white'. This would be fine, except that both colour film and digital
sensors don't have a continuous response either: they have dye layers, or
sensor sites, sensitive to different 'colours' and the mixing gives us the
end result - this means that you can get interaction between the spikes in
the emission of the lamps and the colour sensitivities of the film/sensor.

Overall, this means that good fluorescent sources can be used effectively
for photography, if you can cope with the relatively low power, but that
they will give slightly different results on every different film (or
sensor) and will sometimes do strange things to particular materials
(coloured fabrics that produce their colour by mixing a number of different
shades - such as some silks - are the famous example of such problems.)

Lots of photographers use flourescents for their particular qualities, but
you need to test the results against your particular film - and be prepared
for occasional surprises.



Peter

 

What's the variation of brightness in a CF over an AC cycle? Probably
2 stops at least. 100/120 hertz. With shutter speeds less than 1/60th
you stand a good chance of hitting a dark spot, or a bright spot in the
light's output and your exposure being off noticably.

Frankly, I think they're a bad idea. Go with incandecent or LED.

============================================================
Gardner Buchanan <>
Ottawa, ON FreeBSD: Where you want to go. Today.

 

I recommend the ones labeled, "warm white".......

 

Good point.

LED? Are these commercially available - bright enough to do this?

....beware, most LED driver circuits pulse the power to the LEDs, (so
it can run brighter than spec, but not burn out, and to save power) so
it would have to be built specifically for this job, otherwise you'd
get the same problem.

I actually bought a 100 white LEDs on ebay (really cheap) last year
and never considered making a soft-box. It would be lightweight (could
even make it out of styrofoam board, just punch the LEDs right through
it), fairly thin and run cool too.

How to measure the color temp of this box though? I guess a digital
camera in it's 'set white level' mode would tell me.

I've also got about 80 UV LEDs. Never been sure what to do with these.

I might as well mount them all in the same box, with some reds, greens
and blues so I can modify the color output for special effects. Couple
of variable pots, and bingo!

 

Even your eyes don't

Very good and complete response.

 

Yes, however,

I was referring mainly to their (flourescent or LED) use with digital cameras
which are a lot easier to setup for various kinds of lighting, and of course can
be verified on the spot. For film, most studio work, esp. color critical,
strobe is clearly preferred.

Cheers,
Alan


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The slower shutter speed the better, yes. With flourescent and a decent DOF you
will be shooting pretty slow in most cases. Personally I prefer strobe, but the
fact that CF ganged lights are out there and aimed at the studio digital shooter
is hardly ignorable nor necessarilly a bad idea.

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ESD possibility?

If you look at the link I provided, you will see the color temp specification.

LED brighness is typically controlled with a pulse train and changing the pulse
width (duty cycle if you will) to change brightness.


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Aren't these too blue? The white LEDs in my flashlight and headlamp
seem extremely blue. Maybe they are mixed with a few yellow and red LEDs?

 

'white' LEDs are blue LEDs with a fluorescent material.

B>

 

They do have a strong component at 6500 - 10,000K which is something like
northern exposure / open shade. But this is also combined with warmer light at
the same time from the same LED's (If I'm interpretting the spec sheet right).
Again, as these products are best suited for digital they can be adjusted in
most cameras and verified ... or throw on an 81A/B to get there.

Cheers,
Alan



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Another way to interpret the spec sheet, is that the LED's are available in
"bins" A .. D with progressively higher color temp. I can't find the part
number format, so it's a bit unclear...




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I see no link...

?

Indeed, but we don't want that them to flash because it'll limit the
choice of shutter speed. (Try taking a 100th/sec photo of an clock
which uses 7-segment LED display)

Of course, if I flash em fast enough it won't matter. I can do this
with a 555-timer and a pot. One 555 can run 20 LED's. So 5 banks for
the white and a bank each for red, green, blue and UV.

Not sure about UV's behind a white diffuser, probably wouldn't work
that well.

 

Sorry Alan, I missed your post the first time.

To give you an idea on price, a pack of 60 super-bright whites can be
"Buy Now'd" on Ebay for $0.10 + $15 shipping.

...or another one was 50 of em for $0.50 + $10 shipping.

 

Actually, the latest types are based on a UV led, not blue.

 

Yes, digital makes it easier, and the on-the-spot verification (insofar as
the little LCD screen tells you anything!) is a help.

However, while a digital can adjust how it blends the signals from its three
colour channels to address more or less any colour temperature, it still
can't completely deal with a 'spiky' source. An extreme example would be a
mercury vapour discharge lamp: whatever you do you won't get perfect colour
balance with that, because it isn't a black-body (continuous spectrum)
source, but has very specific, narrow, emission lines.

Photographic fluorescents (and LEDs) have much smoother emissions than
mercury or sodium vapour lamps, with many more, and less pronounced, peaks
and troughs so the overall effect comes closer to a continuous spectrum
source. This means you can come closer to correcting them in camera, with
digital, and can _usually_ get full correction (if you relly need it) if
you work hard after that in PS. And, as I said, for many subjects the
results will look absolutely fine right from the start anyway.

But both film and digital 'see' in terms of mixing three (or, for some
films, more than three) colours, and so both _can_ have trouble with
fluorescent sources and for exactly the same reasons. It's just that with
digital you can adjust how those colours are mixed, so having the effect (in
this respect anyway) of giving you a whole range of films to choose from.


Peter