1 - Position (i.e. Not Backgrounds)

Thank you for continuing to follow my progress through the Lighting Boot Camp (LBC) and the Lighting 102 (L102) courses from strobist.com.

Last weeks headshot assignment from LBC focused on creating a finished product.  I was very happy with the end results of the assignment, but I couldn’t really break down why it turned out so well.  To be honest, I pretty much blindly plodded my way through the two-light setup.  Stick a light here, stick a light there, fiddle with them a bit and voila – a finished product.  The L102 course, in contrast, is “a comprehensive course that starts from square one”.  As David Hobby (the author of strobist.com) put it, the Boot Camp skipped right to desserts while in the Lighting 102 course we have to eat our veggies first.   After progressing a bit more into L102, I realized that what I was learning could really impact how I attack the next LBC assignment.  As a result, I decided to pull back on the reins a bit in regard to the LBC assignments and focus on the L102 course.

In the last post I also shared with you some of my tricks that I’ve picked up along the way before getting in to this off-camera flash work.  From this point forward I’ll be venturing into areas that are well outside my comfort zone.  I may not have as many tips to share but, by focusing my posts on the L102 course I hope you’ll be able to learn with me as I progress.

L102 teaches us that there are seven ways to control light.  In this post I’ll detail my work through the first two, position and apparent light size.  Both of these controls are broken down into two pieces for easy digestion.   Position is broken down into Angles and Distance while Apparent Light Size is broken down into a section on Apparent Light Size and then Specular Highlight Control.   Wait, specular what?!  Yeah…now you understand my reaction to pull back on the proverbial reins.

One nice thing about these controls is that all four played roles in my Headshots assignment…I just didn’t know at the time.  Similar to the first time you learned about the Scientific Method.  Daunting at first but then you realize you’ve been doing it your whole life.  Question: What happens if I hit A. a matchbox car, with B. a hammer, Hypothesis: I think it’ll be cool…bam, Result: it was cool, experiment successful.  When I was a kid I doubt I could even say hypothesis but I was forming them.  The same type of thing happened during the headshot assignment.  I was dealing with angles, distance, light size and highlight control without really knowing it.  As we work through these sections try to think about how these controls affected the headshot shoot and how we can use them to change the end result.

We’ll begin with angles, which is a pretty intuitive concept.  Changing the angles between the light source, subject and camera will make the subject look different.  Think of someone standing outside on a sunny day.  As they rotate, or you move around them the sun lights different parts of their body and casts different shadows.  Now think of your flash as the sun being moved around a subject.  Luckily I have a buddy named Snowball that was happy to get out of storage to illustrate this for us.

In this example the light source is being moved from the left side of Snowball to around 45 degrees as you look across the rows in the collage, and from a higher angle to a lower angle as you down the columns.  As you can see the light reflects off Snowball’s face as you would expect.  Those of you with a keen eye might ask why I used Snowball and not Spooky (it is late October).  Unfortunately Spooky doesn’t have a nose and Snowball’s schnoz casts a helpful shadow.

The second part of position is distance.  The first part of distance is again pretty intuitive.  The closer your light source is to the subject the more powerful it is.  This phenomenon is called, or explained by the Inverse Square Law. If that isn’t clicking with you think of a group gathered around a campfire.  The ones closer to the campfire are brighter than the ones farther away.  There is a whole lot more to the law but for this exercise this is all you really need to know.

What I found incredibly interesting about distance was that flash, similar to a camera lens, has a depth of field.  With enough lighting power you can make a black background look white and with enough distance you can make a white background look black.  This is one of those, “this will be on the test” moments, reread the last sentence, it’s important.  We know that the distance between a light source and a subject has a major impact on the relative power of the light thanks to the Inverse Square Law.  Equally important is the relative distance to the light source of multiple objects.  Take a look at this next set of photos of Snowball and see if you can tell what’s happening and more importantly why it’s happening.

These three photos were taken with the exact same camera to Snowball distance and the same Snowball to background distance.   The background was around 4 feet from Snowball.  The flash used for these shots was on manual firing at a constant power.  The only thing that was modified was the distance between the flash and the subject (Snowball).  I used the aperture to control the flash exposure but all other factors were the same (ISO, shutter). What you’re seeing is that “flash depth of field”.  The flash is being moved yes, but more importantly is the ratio between flash-subject and flash-background is greatly changing.  

Helpful Hint: Shutter speed and aperture affect the ambient light exposure but only the aperture affects the flash exposure.  This is because flash is pretty instantaneous.  If your flash is too bright crank down your aperture, lower the flash’s power or move it further away from the subject.  See Lighting 101 (L101) for more on balancing ambient and flash exposures. 

Let’s break these photos down.  The first photo was taken with the flash about 4 feet away from Snowball and Snowball is about 4 feet away from the background so the background is twice as far away from the flash (the ratio is 2:1).  In the second shot I move the flash way in close, about a foot away from Snowball.  Now the background is about four times as far away (4:1 ratio).  Think of the first photo’s background as being twice as dark as Snowball and in the second photo the background is four times as dark.  In the third photo I moved the flash way back, say about 8 feet.  Why did the background get lighter?  Because the ratio between flash-subject and flash-background is getting smaller, now our ratio is only about 3:2.  Below is a sketch of the setup for these photos to help with the visual.

Pretty cool!  Varying this ratio gives someone so much more control over the exposure of the background than I had ever realized.  Kinda makes sense now why I postponed the LBC Backgrounds assignment right? 

I said at the beginning that I was going to get into Apparent Light Size but while writing this I’ve changed my mind.  I’m going to try and err on more frequent shorter posts than less frequent longer posts, at least hear at the beginning.

Regardless if this is making sense to you or not, it’s important to try these exercises yourself so you become familiar and comfortable with them.  If you are limited by an on-camera flash you can still do the distance exercise.  In this case, the maximum flash distance will be limited by your largest zoom capability but the premise will be the same.  If you have a newer Canon or Nikon speedlite you should be able to use the flash off-camera without any additional equipment.  This may require you to read some of the manuals that came with the camera and flash to do so but it will be worth it.

As always, please ask questions if you have them.  I would also love to see your own results from these exercises so please share.  Thank you again for following.  In the next post I will get to my progress through Apparent Light Size and Secular Highlight Control.

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