So after posting my latest SooC52 image, a few questions from my fellow togs popped up. I thought I'd make a brief "How I Did It" post to answer a few of them, including how to make these nifty light domes !
I'll keep it fairly simple so that if you aren't to comfortable in manual mode with your camera it's not too heavy going.
Ok, So lets start at the beginning. The way a camera works in it's basic form is that the shutter opens and allows light to hit the sensor. To have an image that looks right and is not too dark (Underexposed) or to light/white (Overexposed) the shutter must be open for a set length of time. With night time photography, the shutter needs to be open for a long time to let enough light in to make a "proper" image. With the settings I needed for my image the shutter needed to be open for 7 minutes.
A side effect of doing this at night in nearly pitch black conditions means that moving object,s that aren't still for long enough for the camera to "see" are not recorded by the sensor. this includes people.
In this image the camera is on a Tripod so it can't move, and the shutter was open 7 mins. I walked in front of the camera twice during this time, but because I wasn't still enough for the light bouncing off me to be recorded by the camera I'm invisible.
The painting bit works because BRIGHT light sources register much much quicker on the sensor, so anything brightly illuminated will show up nearly instantly at that point in the exposure. You can see this on the image below. I was testing that the aperture was dark enough for me not to show up in the glow of my "Dome tools" so the aperture is the same as the 7 minute shot, but the exposure is only 30 seconds becuase I'm not interested in the background.
So because not enough light from the background hits the sensor in 30 seconds, it's too dark (underexposed) so its just a big black expanse.
This bright light source method also applies to flash (strobe) lighting, so below is a test for flash power with my model Rob. Again, I'm not interested in the background yet, so this time the shutter is only open 15 seconds, which gives me enough time to fire the flash by hand twice. Once from the front and once from the back. It's easy to see in this shot that only things hit by the light are visible to the camera. I walked in front of the camera again in this shot but because there is no light hitting me and reflecting into the camera, it cant see me.
So now all I do is add it all together. I set the shutter to be open for 7 minutes, and then once it's open I walk into the frame and begin to "Paint" the domes. I move quickly so that the camera can only see the bright light sources and not me. If I sat still for a minute or two I'd be clearly visible in the frame. Once the domes are done, Rob walks into the scene and I fire the flash at him twice illuminate him in the image. We are both invisible to the camera until we reflect enough light for the sensor to pick up.
Once Rob has been lit, I walk up and use a torch to paint the "Water" coming off the watering can. We both then walk out of the frame and let the exposure finish.
The image below is an out take, all the elements that I mentioned above are there but it went wrong because A) I didn't hit Rob with enough flash for the camera to "see" him properly (To be fair, after the amount of times I fired a flash in his face it's a wonder he hasn't got a tan) B) I wasn't paying attention and painted a dome directly behind where he was going to be stood. Because I did the dome before he was even stood there(About 3 minutes before) it appears over him because it's already burnt into the image.
So that's how I created the image. It sounds a lot more complicated than it is, just think about haw many times you've taken a shot with some lights in it and had a wobble, it leaves lines on your image. This is exactly the same but done deliberately.
Oh yeah, the domes. Easy peasy. Its just a bicycle wheel with some cheap battery LED's taped to it. You need to add an axle that is the same length as the radius of the wheel so it sits at a 45 degree angle. Then just spin it around resting on the axle, like in the image below.
Why can you see my hand and the wheel ?? Because Left the lighting on in the garden so you could see the wheel, this also means that I reflected enough light for the camera to see me moving about.
I hope you're not all too baffled with this, and that you give it a bash because it's good fun :-)