4.1 - Restricting Light

I’ve made it through the first three ways to control light: Position, Apparent Light Size, and Balancing.  Here’s a quick review of what we’ve discussed about these three controls.  Position will affect what is lit and what is in shadow and changing positing (or distance) will affect the power of the light.  The apparent size of the light source affects the length of the transition between highlight and shadow or in other words how hard or soft the light is.  Then the course got into how to use aperture and shutter speeds to balance between ambient light and flash. 

The next lighting control in the Lighting 102 course is restricting light.  This is a fairly simple concept to grasp, but it has some strange terminology.  David Hobby (author of the L102 course) separates restriction methods into four classifications: gobos, snoots, grid spots, and cookies.  These seem to be fairly standard terms they do vary a bit depending on the source.

Gobos

The term “gobo” is short for “goes between optics” and is anything that shields a lights source.  Typically gobos are used to either shield the flash from spilling on to something in the photo’s frame or to avoid lens flare by shielding a the flash from the camera lens.  The Lighting 102 example of a gobo was a piece of cardboard, or something similar, attached to one side of the flash.

Figure 1: My gobo with the supplies I used to make it.

To the right are the tools and supplies I needed to build my own little gobo; a cereal box, hockey tape, scissors, and Velcro strips to attach it to the speedlite body.

Figures 2 and 3 below demonstrate how a gobo can be used.   The photos were taken with a flash set up to the left of the subject.  Figure 2 was taken without the gobo and Figure 3 was taken with the gobo attached. 

To help visualize what is happening in these two shots I took a step back and took photos of the whole set up.

Figure 2: Flash camera right with gobo attached.	Figure 4: Flash with gobo.
Figure 3: Flash camera right without gobo attached.	Figure 5: Bare flash.

By attaching the gobo to the side of the flash, it acts as a shield and prevents the light from spilling onto the wall behind Mr. Lego man.  This is just one example of how a gobo can be used; they can be made in any size or shape and are used to prevent light from spilling into unwanted areas.

Snoots

Figure 6: My snoot with the supplies I used to make it.

Gobos are used to shield a light in one direction but if you want to shield the light source in all four directions you can use a snoot.  Snoots are basically four-sided gobos that fits over the front of a flash.  A snoot restricts the light in all four directions effectively narrowing the beam of light.   

I made a snoot from the same materials that I used to make my gobo.  Using gaffers tape would have been a lot easier than the hockey tape but, I utilized the materials I had at the time. 

The length of a snoot will determine the narrowness of the light beam.  You can buy them, or make them, in any length you need.  If you make your own snoot, make sure it fits snug on your flash so it doesn’t falls off easily. 

This photo was taken with a bare speedlite zoomed into 105mm aimed at a wall.

Figure 7: Bare flash, no attachments.

This is the same lighting set up with the snoot attached.

Figure 8: Flash with snoot attached.

A snoot doesn’t have to have square or rectangular sides.  Snoots, like gobos, can be made into any size or shape to restrict the light in the desired way.

Grid Spots

Grid spots are like fancy snoots and as you may have been able to guess, they offer even more control over light.  For the sake of being consistent, I decided to make my own grid spot as well and used Rui M. Leal’s tutorial here for help.

Figure 9: A look through my grid spot.

For this build I had to buy some supplies.  I needed black straws and I finally picked up some gaffers tape to make my life easier.  Gaffers tape is a bit more expensive than other types of tape but it is much easier to work with.  Gaffers tape is used extensively in any type of stage work because it can be removed cleanly without leaving a residue (unlike duct tape).  It’s also strong but easy to tear making it great to use with expensive camera gear.  Together with some glue (I used silicone but any glue would work) and the same basic supplies from the gobo and snoot, I had everything I needed.  This is what my grid spot ended up looking like.  The structural shape is similar to the snoot but straws are added to create the grid spot.

Here’s another look at it.

Figure 10: Photo showing my grid spot's shadow.

So how is the grid spot different than a snoot?  To find out, I first constructed a similar light setup to the one I used to test out the snoot.   I then took a series of photos starting with a bare flash, moving to the snoot, and ending with the grid spot to show the progression of light restriction.

Figure 11: Bare speedlite zoomed to 105mm aimed at a wall.

Figure 12: Same light setup with my snoot attached.

Figure 13: Same light setup with my grid spot attached.

Surprised by the shape of it?  I sure was!  You can see from the previous photos that the grid spot is rectangular, so why is the light pattern round?  Obviously it has something to do with the straws but beyond that I’m fairly clueless as to the physics behind this.  If you can explain this little phenomenon, please add it to the comments at the end of this post.  This was a result that I was definitely not expecting.

Cookies

Cookies are anything that you put in front of the flash to create a pattern.  Sometimes cookies are also referred to as gobos that you shoot the flash through.  Cookies are used to produce a particular pattern of light and can be bought or made by using every day objects.

Here are a couple photos of a background that I took using improvised cookies. 

Figure 14: Pattern created with cookie #1.

Figure 15: Pattern created with cookie #2.

Cookies are useful for livening up a background.  Now, I said that these cookies were improvised and I truly mean that.  I didn’t have a leafy plant (a quick natural cookie) to use around house but while I was walking through my kitchen I did find a couple things that I could use.  I repurposed a pancake spatula and a fish flipper as cookies.  To prove it I took two more photos showing these improvised cookies.

Figure 16: Pancake spatula cookie.

Figure 17: Fish flipper cookie.

It is interesting what you can create with a few household items.  Typically I work out of my camera bag for my photography, but with this shoot it seems I was working mostly out of my kitchen!

I’m going to continue to experiment with my new gobo, snoot, and grid spot a lot more to get a good feel for how I can use them to enhance my photography.  Luckily, I get just that chance in the very next assignment.  Thanks again for following and please ask any questions you may have.

previous - next

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.

previous - next