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.

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Headshots Review

My previous two posts described my progress through Lighting 102 lessons on Strobist.com two ways to control a light source, position and apparent light size.  These controls had a major impact on the end result of the Lighting Boot Camp assignment on Headshots.

In an earlier post, I admitted to you that I was blindly plodding my way through the Headshots assignment.  Now that I understand position and apparent light size better I wanted to go back to this shoot and explain in more detail how this shot was created and how these controls affected the end result.

I’ll begin with apparent light size.  In the last lesson I learned that the apparent size of our light source affects how large the transition is between highlight and shadow. To produce soft light an apparently large light source is required.  Soft light extends the transition between highlight and shadow.  In contrast, apparently small light sources produce hard light and reduce the transition between highlight and shadow.

In my headshot shoot I used a combination of hard and soft light sources.  I wanted my main light to be soft so I used a shoot-through umbrella positioned slightly higher than the model’s head on the camera left side.  This position creates shadows under the model’s nose and chin.  These shadows add dimension to the model’s face but by utilizing an apparently large light these shadows are softened.  

I envisioned my second light source being natural light coming through a nearby widow camera right.  It was partly cloudy the day of the shoot, so my light source kept going in and out.  Instead of dealing with nature I set up a second speedlite in front of the window.   I left this speedlite bare, making its apparent size small.  This produced hard light and you can see the transition between highlight and shadow on the left side of the models face is really small.  

By modifying the apparent size of either of the light sources the transition between the shadows and highlight can be changed.

Distance also affects the apparent size of a light source.  This shot was taken in a relatively small room.  Adding or removing an umbrella was more effective in modifying the size of the light source than altering the distance between the subject and the light source.  However, the distance of the light source did have a major effect on the exposure of the background.  If I wanted to darken the background without repainting the wall I could have moved the umbrella light closer to the model and taken advantage of the flash’s depth of field. 

Don’t forget about the Specular Highlight.  A specular highlight is light reflecting directly off an object into your camera.  Even though it seems that the human face is not a reflective surface, it is, and specular highlight does come into play.  The 3-dimensional attributes of light toned objects are defined by shadows and dark toned objects are 3-dimensionally defined by specular highlight.  This has a major impact when dealing with subjects with different skin tones.  In this shot, the models skin tone is fairly light so the shadows are giving the photo a 3-dimensional look.   

Regardless of the model’s skin tone specular highlights also show up in the models eyes.  These specular highlights in the eyes are called catch lights.  Catch lights make a photo look more natural.  You can typically tell the shape of the light source by looking at the shape of the catch light in the subject eye.  The shoot-through umbrella used in this shot creates the round catch light.  If a rectangular softbox was used the catch light would be rectangular instead of round.

As a general rule of thumb (insert Boondock Saints opening scene), the shape of a catch light should mimic a natural catch light.  For instance, for an indoor photo the light source creating a catch light could be a window creating a rectangular catch light so creating one with a rectangular softbox would be appropriate.  For an outdoor photo creating a rectangular catch light wouldn’t match a natural round catch light caused by the sun.  I’m not saying that softboxes shouldn’t be used in outdoor photography; professional photographers used softboxes outdoors all the time.  I just want you to be aware of the shape of the catch lights that you create.  This might not seem like a big deal, but gaining an understanding of this can help you determine if the shape of the specular highlight is important in your own photography. 

Another neat thing that I learned from Strobist.com is that you can further alter your light modifier by blacking out a portion of it.  A logo, design or even wording can be added to a light modifier and it will show up in the specular highlight.  I haven’t personally tried this yet but when my new softbox comes in I might.  I’ll let you know how it turns out in a future post.

The subject of my next post will be the L102 Cooking Light assignment.  When I was working on the cooking light shoot I thought back to how these controls affected my headshots assignment.  It was important and helpful for me to relate my newfound knowledge to my previous work and I wanted to share it with you.  I hope that this helps you further understand the position and apparent light size controls.

For more on specular highlights and working with skin tones check out Lighting 102: Unit 2.2: http://strobist.blogspot.com/2007/07/lighting-102-unit-22-specular-highlight.html

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