continuous vs strobe for product photography

Started Oct 31, 2013 | Discussions thread
Duncan C Veteran Member • Posts: 7,674
Re: Make sure you use high CRI lights, whatever you choose.
2

A couple of people have mentioned CRI, but nobody has explained it, so I will.

Daylight is "full spectrum", meaning that it has light at all wavelengths. The mixture of different wavelengths looks white to us.

Flash (xenon light) matches the spectrum of daylight quite closely, so it looks very natural.

Both flash and tungsten lights emit what's known as "back body" radiation, which is the kind of light when you heat a substance to the point where it glows. The hotter you heat it, the bluer the light you get. The temperature you use is known as the "color temperature." Cameras can adjust for different color temperatures using white balance adjustment, and the results will be very good.

Other light sources like LED or florescent tend to be quite weak in certain wavelengths (or even completely missing) and too hot in other wavelengths. When a wavelength is totally missing, certain colors in your subject won't look right, and no amount of color correction can add back wavelengths that are too weak or completely missing.

There is a measurement called CRI, which stands for Color Rendering Index. It is a measure of how close the light source is to a "true" black body light-source. 100 is perfect. Anything less than about 92 is bad for photography, and 96 is better still.

Ordinary fluorescents and LEDs tend to have a low CRI, and cause color problems that are pretty much impossible to completely correct. If you're going to use one of these light sources, you need to spend more money and get high CRI lights. If no CRI information is available, you can be sure they are not high CRI bulbs, and they should be avoided. (High CRI bulbs are more expensive to make, and so manufacturers that make high CRI bulbs will brag about it.)

Mastov wrote:

I do web design for my company but recently fell into the role of also taking product photos. I am not a photographer, so I have zero experience using lights. I've begun reading "Light Science and Magic" but I still have questions.

1)

Most people seem to recommend "strobe" lights over "continuous lights". I can understand using strobe lights for portraits of people so as to not blind them or cause heat discomfort, but strobes seems impractical for product photography. I've tethered my camera to the computer to see the view finder on the screen using a program called "Capture One". This allows me to see lighting adjustments in real time before I take the photo. So with "Continuous" lighting I can tweak the light as I'm watching the screen. But with "Strobe" lighting it seem's I cannot adjust the light in real time and get immediate feedback.

2)

This is related to (1). When I visit a place like BH Photo or Adoram, I see the break down between "strobe" and "continuous lights". Then within "strobe" and "continuous lights" there are a lot more options. I see the following break down:

"continuous" = LED, Tungsten, Fluorescent, HMI

"Strobe" = Monolight

If my understanding is correct "Tungsten" and "Monolight" are the two most common lights. "Tungsten" for "continuous" and "Monolight" for strobe. Most people prefer "Monolight" since it's not "hot".

LED is mostly used for film? The current consensus is that it's expensive and build quality is unpredictable. If LED technology is improved this would be favored over Tungsten.

HMI is used on big hollywood sets. There aren't any complaints, except that it's expensive so most photographers don't use it. Like LED most people would prefer this if they could afford it.

Fluorescent is cooler and uses less energy, but it doesn't give much light. For continuous lighting "Tungsten" is preferred over "Fluorescent".

Is my understanding correct? Or am I off base?

3)

Since I will only be shooting non-animate objects is continuous lighting from a Tungsten set the best way to go?

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Duncan C
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