Lighting technique question...

Hi all,

I have a quick question:

I was wondering how you get that "star" effect when you have a strobe pointing toward the camera and firing from behind a subject? Same idea as how the sun can look when you're outside and shoot in the range of f16 etc...I was just trying a 'rock star' look with one of my boxers. Here was the setup:

Black background
One strobe to camera left, pointing toward camera. This was an elinchrom 300RX, with just the reflector
The boxer was about a foot in front and to the right of strobe
One 300RX strobe with softbox (100cm x 100cm) to camera right feathering as a main light .

The end result was that the back light was just shy of blowing out - was an OK look but not close to what I wanted.

Should that light in the back be stopped WAY down? Is this an effect that only works when I'm not too close to that light in the back? I thought by bringing the aperture down, that would work but it didn't

I only had 10-15 minutes to mess with this, but he had his fill

I was hoping for a suggestion or two so when I try again on Saturday, I have a starting point.

Thanks!

Thunderbird33 wrote in post #10968968
Hi all,

I have a quick question:

I was wondering how you get that "star" effect when you have a strobe pointing toward the camera and firing from behind a subject? Same idea as how the sun can look when you're outside and shoot in the range of f16 etc...I was just trying a 'rock star' look with one of my boxers. Here was the setup:

Black background
One strobe to camera left, pointing toward camera. This was an elinchrom 300RX, with just the reflector
The boxer was about a foot in front and to the right of strobe
One 300RX strobe with softbox (100cm x 100cm) to camera right feathering as a main light .

The end result was that the back light was just shy of blowing out - was an OK look but not close to what I wanted.

Should that light in the back be stopped WAY down? Is this an effect that only works when I'm not too close to that light in the back? I thought by bringing the aperture down, that would work but it didn't

I only had 10-15 minutes to mess with this, but he had his fill

I was hoping for a suggestion or two so when I try again on Saturday, I have a starting point.

Thanks!

You've already answered your own question....use a very small aperture.

Or, you could use a "star-effect" filter over the lens.

PacAce wrote in post #10969116
You've already answered your own question....use a very small aperture.

Or, you could use a "star-effect" filter over the lens.

Interesting....I had actually went all the way down to f22 but it was still way too hot and there was little flare, but my hunch now is that the light itself was just too bright then for my distance to it even though I dialed it back some. Good idea on the filter too.

Thanks!

The "star" shape is a natural effect of your aperture and exposure value. There isn't a magic aperture where this will happen, but it is easier to get it to happen at smaller apertures; but you HAVE to be stopped down somewhat to get this effect. The exposure value on the point light source has to be within a reasonable range to get a good star effect. So depending on your ISO or shutter speed, you can generate a star at F/8 and NOT get one at f/16. But it definitely is easier to produce the star effect at small apertures. Just don't overexpose the light sources too much.

A lens with an EVEN number of aperture blades will generate a star with the same number of points as blades. A lens with an ODD number of aperture blades will generate TWO points on the star for each blade.

In reality, both even and odd aperture bladed lenses generate TWO points for each blade, but the even bladed lenses have two stars that are superimposed on top of each other so it only looks like it has one point per blade.

The star points are actually diffraction spikes due to the non-circular shape of the aperture. That's why you cannot create this when wide open. The more you stop down, generally, the less circular the aperture is, which is why it's easier to generate this at smaller apertures. This is also the reason why this effect shows up at wider apertures in lenses that have less blades due to the fact that it is less rounded right from the start.

picturecrazy wrote in post #10970361
The "star" shape is a natural effect of your aperture and exposure value. There isn't a magic aperture where this will happen, but it is easier to get it to happen at smaller apertures; but you HAVE to be stopped down somewhat to get this effect. The exposure value on the point light source has to be within a reasonable range to get a good star effect. So depending on your ISO or shutter speed, you can generate a star at F/8 and NOT get one at f/16. But it definitely is easier to produce the star effect at small apertures. Just don't overexpose the light sources too much.

A lens with an EVEN number of aperture blades will generate a star with the same number of points as blades. A lens with an ODD number of aperture blades will generate TWO points on the star for each blade.

In reality, both even and odd aperture bladed lenses generate TWO points for each blade, but the even bladed lenses have two stars that are superimposed on top of each other so it only looks like it has one point per blade.

The star points are actually diffraction spikes due to the non-circular shape of the aperture. That's why you cannot create this when wide open. The more you stop down, generally, the less circular the aperture is, which is why it's easier to generate this at smaller apertures. This is also the reason why this effect shows up at wider apertures in lenses that have less blades due to the fact that it is less rounded right from the start.

Very interesting and informative. Thanks.

That's some great info! Thanks for taking the time to add that.