Wednesday, December 29, 2010
BALANCE.........it's not just a test the police use........
Holy cow. Two blog posts in one week............................yeah..................I'm the man.
At the end of my previous blog post I wrote: "It all comes down to knowing what you want to happen, and then being able to find that balance between your different light sources to achieve it." I'm going to try to expand on the meaning of that sentence today. Follow the jump for more...
First off, though, I need to give credit where credit is due. I owe pretty much every ounce of my knowledge (all 2 and a half ounces of it) on this subject to a Mr. David Hobby (aka THE Strobist). You can find his blog here. For those of you who are not familiar with Mr. Hobby, he is kind of like the godfather to noobs like me. His blog is chock full of goodies and informational nuggets complete with examples images, lighting setups, diagrams, pretty much everything you could ask for and more. Plus it's all free content. If you manage to get any usefull info at all from my blog, I can almost guarantee you that you will recieve it ten fold from his. In other words.............look at his blog............it's really freaking good.
Now...........................ON WITH THE SHOW
My example images today are meant to demonstrate balance between ambient twighlight and off camera flash. Ambient light can be thought of as any available light that is not produced by a flash. In this case, our ambient light is daylight from the setting sun. If you were inside, your ambient light could be light from a lamp in the room, as well as light coming in a window.
Above you see an image of Carly. I was fortunate enough to take her senior pictures this past fall. It's pretty obvious that I couldn't have asked for a more beautiful model. Add in an awesome sunset and I came out of this shoot thinking pretty dang high of myself (I'm really a very humble person, just ask my wife......on second thought....). In all reality, though, the pieces were laid out perfectly for me. All I had to do was find my base exposure for the ambient light (the sunset), determine my flash power, and after that, it was off to the races. In my opinion, there is no better way to build self esteem for a photographer, than to learn how simple it is to balance an off camera flash with a setting sun.
For the image above, I found my base exposure to be f-4 @ 1/160th of a second. Shooting in manual mode at this exposure would expose the sky and setting sun just the way you see it every time. Now that I had my ambient light exposed how I wanted, all I had to do was find my flash power. The majority of my outdoor shoots are done with only one light that is held on a monopod by the most beautiful assistant EVER (no not Vanna White.....my wife). Having someone to hold my off camera flash is awesome for mobility, as well as piece of mind knowing that the wind isn't going to knock over my lightstand. I can't be for sure, but I would be willing to bet that I had my flash set to 1/4 power or so. I was also using a westcott 43" shoot through umbrella. Using the umbrella gives you nice soft light, which is perfect for a young woman.
Here's the lighting set up diagram:
Once again, I apologize if the text is too small to read, but you should be able to click on the image to see it bigger. So, basically you see the off camera flash coming in high and camera right. I actually had my assistant (beautiful smoking hot wife) holding the flash as close to Carly as possible without entering the frame. Having a diffused light source so close to your subject gives you softer light, as opposed to placing it farther away(more details on why coming in future posts). Now that I know my base exposure (f4 @ 1/160th), and flash power (1/4 powerish), every pic I take for the next few minutes before the sun sets further should be exposed exactly the same, provided the distance between my lightsource and subject remains constant (you know, that whole inverse square thing). Piece O' cake right? Trust me, it is. Any fellow strobist reading this right now knows what I'm talking about is probably trying to stay awake.
On to the next image (that's right there's more, now quitcher bellyachin!)
This image was taken approx. 10 minutes after the first image. The sun had gone completely down at this point, but we still had plenty of ambient light and a beautiful backdrop of a sky to work with. Since we were losing our light fairly rapidly, I had to adjust my shutter speed to compensate. Instead of 1/160th of a second, I reduced my shutter speed to 1/60th to keep everything besides Carly from going too dark(Carly's exposure is mostly coming from the flash). That's roughly a stop and a half. Now, your shutter speed has no effect whatsoever on your flash exposure. I'll say that again because it took me a while to really understand even though it's pretty simple. "Your shutter speed has no effect whatsoever on your flash exposure." Why? A flash fires all of it's light within several thousandths of a second, so, as long as your aperature doesn't change, you will see the same amount of exposure from your flash regarless of wether your shutter speed is 1/60th or 1/500th of a second. I also opened my aperature from f/4 to f/3.5 to brighten up the sky just a little more. Now, when you bring aperature (or f-stop) into the picture, that's when you have to start adjusting your flash power. Your aperature physically controls how much light can reach the sensor, so since we opened our aperature to let more ambient light in, I reduced the power on my flash to 1/8 to keep from overexposing Carly. Anybody know what else I could have done to keep the flash exposure constant without adjusting the power?............................................................that's right (your wicked smart), I could have increased the distance between the flash and Carly. But I didn't want to do that becuase I wanted as soft a light source as possible. If your reading all this and wondering what the crap i'm rambling on about and would like to have it explained in great detail, I advise reading lighting101 on the aforementioned Strobist web page. I can't say enough about how good the content is.
The image above was taken approximately 5 minutes later than the second image. If you compare the two, it's obvious the sky is much more underexposed in this image than the second. I did this intentionally for a couple reasons. In order to get a good frozen image of Carly jumping, I wanted to set a shutter speed faster than 1/60th. The second reason was that I wanted Carly to really "pop" against the background. The exposure for this image was f 3.2 @ 1/100th of a second. I knew that I could reasonably freeze her jump with the 1/100 shutter speed, and we had just enough light left to keep some detail in the sky and background. I could have opened up my aperature to f 2.8 to lighten the background a bit, but I preferred the heavily underexposed background in this case. In order to light Carly, I brought in another speedlight and "crosslit" her from far camera right and far camer left. Diagram below:
This diagram shows two bare speedlights lighting Carly from both sides. You can see spill from these flashes on the ground below Carly. I can't remember exactly what power the flashes were set to, but I would guess around 1/4 power or so.
So there you have it. Knowing how to balance your ambient light with your artificial light is one of the most useful tools in your camera bag and when you get the hang of it (it's really not hard, I can do it for goodness sake, and I'm not smart like Keanu Reeves or anything), you will be amazed at the images you can create with relatively little effort.
Next week, my goal is to give a rundown on some of my equipment choices such as lenses, flashes, triggers and whatnot. Thanks for reading and feel free to leave me any questions or observations in the comments section. Have a safe and happy new year.