Question about lighting...

[splproductions]

What is the difference between using a Speedlite shot through an umbrella or softbox, and just putting some type of daylight-temperature bulb in the umbrella or softbox? I.e., a constant "ambient" type light versus the quick burst of light?

Are there situations where I'd want to mix it up - one Speedlite and one constant light?

 

[BuS_RiDeR]

Usually... the power of the light source.

 

[MLeeK]

The speedlight puts out MUCH more power than the bulb. You'd have to have about 25 bulbs to equal to one low power speedlight. If you are mixing the two it won't make a whit of difference because the speedlight will overpower the bulb.

 

[o hey tyler]

What speedlights can do is freeze motion. You can shoot on 1/200s at f/8 ISO100, and you'll be only exposing for your flash (indoors, in a studio lets say). With hot lights, you'll need to have a much longer shutter speed, because to equate the same exposure as the flash, you'll need to let the sensor see more light at f/8.

Hot lights are great for things that don't move. Like product photography. Because you can actually see how the light will wrap through the modifiers. But for shooting people, I'd suggest flash(es).

I personally wouldn't mix it up, unless I was using the modeling light on my monolight... Even then, it turns off when the flash fires.

 

[o hey tyler]

....because the speedlight will overpower the bulb.

Depending on what your shutter speed is. ;-)

 

[splproductions]

The speedlight puts out MUCH more power than the bulb. You'd have to have about 25 bulbs to equal to one low power speedlight. If you are mixing the two it won't make a whit of difference because the speedlight will overpower the bulb.

Oh... wow! Good to know. I feel pretty stupid right now, because I was thinking the exact opposite - that I'd need to get several Speedlites in there (which would cost a lot) to equal the power of several bulbs (which would cost far less).

I'm looking at some of the setups in Syl Arena's "Speedliter's Handbook"... and some of his setups have 8+ speedlites in them. I'm just hoping that for my family-portrait type work that two 580's will be plenty.

 

[o hey tyler]

I'm just hoping that for my family-portrait type work that two 580's will be plenty.

Yes, they should. Unless you're shooting Octo-Mom's family. You might need some more light for that.

 

[Trever1t]

a 500 watt constant light is 500 watt hours or .138 watt seconds...doesn't sound so bright does it?

My math right?

 

[splproductions]

a 500 watt constant light is 500 watt hours or .138 watt seconds...doesn't sound so bright does it?

My math right?

I guess I should have reasoned my way through that. I took a year of physics... this was the one time it would have done me some good!

 

[KmH]

a 500 watt constant light is 500 watt hours or .138 watt seconds...doesn't sound so bright does it?

My math right?

Sort of, but it's not hours - it's seconds. One watt = 1 joule per second. So 500 watts is 500 joules per second.

Where the math comes in is when one uses a shutter speed shorter than 1 second. At 1/100 for the shutter speed, that 500 watt light effectively becomes a 5 watt light. At 1/200 it's effectively 25 watts.

Many product shooters use constant lights because they can use a 1 second or longer shutter speed. 1/100 is about the slowest shutter speed we want to use to shoot people, because people tend to move a bit.

As mentioned, constant light is effectively ambient light, whereas strobed light (flash) has a short duration and can be effectively used in lieu of the shutter speed to stop motion.

A Nikon SB-600 set to full power produces a flash of light with a duration of about 1/900 of a second. Set to 1/4 power, the flash duration is even shorter, about 1/3400 of a second, and at 1/64 power is about 1/25,000 of a second.