4 things you need to know about light

[rosserx]

This is a really good article. I want to pass it along. Enjoy! The 4 Things You NEED to Know About Light | Your Photo Tips

[sk66]

One significant "error" (maybe "ambiguity" would be better)

"The closer your light source the softer it becomes"
In most senses, this is *wrong*.
If you move a constant power light source closer it does NOT become softer...The light has much less time to spread and becomes harder/harsher.
If you reduce the light output proportionally as you move it closer it does become "softer", but in fact, the result will not be "softer". The light will not wrap as far or spread as wide. What get is *the same* soft light but of a smaller area.

[nickbedford]

Actually it's more right than wrong. For the most part. Or something.

A given light source area will appear "larger" the closer it gets to the subject as the angle from each side will be larger. To achieve the same area from far away you need a larger light source. With that being said, the intensity will increase the closer you get but that's separate from diffusion as intensity can be controlled by the camera settings and power to the light.

The orange is the light source area:

[dalmorloson]

Originally Posted by sk66

One significant "error" (maybe "ambiguity" would be better)

"The closer your light source the softer it becomes"
In most senses, this is *wrong*.
If you move a constant power light source it does NOT become softer...The light has much less time to spread and becomes harder/harsher.
If you reduce the light output proportionally as you move it closer it does become "softer", but in fact, the result will not be "softer". The light will not wrap as far or spread as wide. What get is *the same* soft light but of a smaller area.

As a newbie I'm confused. Everything I read says that a large light source is softer the closer it is to the subject. It seems strange that that is the case and now you dispute it. So now I'm confused. I just started taking pics and want to invest in some lighting so I have to get this straightened out.

[sk66]

Originally Posted by nickbedford

Actually it's more right than wrong. For the most part. Or something.

A given light source area will appear "larger" the closer it gets to the subject as the angle from each side will be larger. To achieve the same area from far away you need a larger light source. With that being said, the intensity will increase the closer you get but that's separate from diffusion as intensity can be controlled by the camera settings and power to the light.

The orange is the light source area:

Your drawing is goofy....
How is the light source narrower from further? That can only happen if you zoom/snoot the source.
Yes, the source will "appear" larger, and more intense (for a constant source) but it will not wrap as far.
In your drawing use only the wide lines (given light spread for a given source which doesn't change)

[sk66]

Originally Posted by dalmorloson

As a newbie I'm confused. Everything I read says that a large light source is softer the closer it is to the subject.

This is true *IF* you decrease the intensity to achieve the same exposure, but it will not spread/wrap as far.

[zona5101]

I defer to Light: Science and Magic which states the larger the light source the softer it appears... some might draw the conclusion that moving it closer would increase its size and therefore make it softer?

[SusanH1970]

Originally Posted by zona5101

I defer to Light: Science and Magic which states the larger the light source the softer it appears... some might draw the conclusion that moving it closer would increase its size and therefore make it softer?

Agreed. When I want very soft light when using my AB, I bring it in as close as possible; often I have to clone out the softbox in post.

[OsmosisStudios]

Originally Posted by zona5101

I defer to Light: Science and Magic which states the larger the light source the softer it appears... some might draw the conclusion that moving it closer would increase its size and therefore make it softer?

Sorry sk66, but this is general knowledge. The sun is a massive light source, but it's so far away that it "appears" small. Put a 60 watt bulb a few inches from a subject and it's HUGE in relation.

[nickbedford]

I've revised my diagram as to why this is the case. Assume this is the face of the softbox that Susan is using.



Notice how it wraps around more? Not only that, but the angle of light is actually more prevalent than the amount it wraps around the subject.

When far away the light is predominantly hitting it from an almost parallel direction (from the right), whereas when the source is close to the subject, light is hitting it from not only the right, but towards the top and bottom.