Softbox size and wattage

maarten_smeenk

maarten_smeenk

Active member
Hi,

I just bought a second hand Hedler c10 head with a 50x50cm (20 by 20inch) softbox. It came with a 300 watt bulb but i replaced it with a 1000 watt bulb, i prefered the softer diffuse light that the 300 watt gave but i need the power at times.

Will a 1 1/3 ND gel filter in front of the softbox with the 1000 watt bulb give the same result as when i used a 300 watt bulb? Do you recommend that (seems like heat will rise when the gel is in front of the fabric).
 
You're not from around here are you?

If the replacement 1K lamp is the same size as the 300 watt lamp, then the level of diffusion will be exactly the same that you have with the 300 watt lamp.

One stop (.3) of ND gel will lessen the output by one stop, or half as much.

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well no exactly Chris. Although the "logical" level of diffusion will be the same because you bring up the intensity of light the shadows on the unlit side will get deeper thus createing an apparent higher contrast (thus less diffused image).
 
Nope.

The only determining factor with respect to the quality of light coming from a fixture as affected by the source is SIZE of the source. If exposure it changed to compensate for the difference in output, the quality of light would be exactly the same as long as spill doesn't come into play. It doesn't matter if you have a 25 watt lamp in a fixture or a 25K lamp in the fixture. If the lamp is the same size/configuration, the light coming from the fixture will be identical with either.

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well you are using mathematics (which i agree with too) but the change in the light intensity will affect our perception of it. and even though the light is of the same size it will "appear" sharper.
 
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