photographic lighting

Indirect light in an Octa

Continuing experimenting with indirect options in large modifiers.

Most softboxes, octaboxes, deep parabolic boxes are used with the light in a “direct” position. That is the light is mounted at the back of the modifier facing forward. This is as opposed to reflective umbrellas where you face the light into the umbrella and have it bounce back at the subject—indirect light. What I have been looking for is a combination where I have a large silver octa or deep parabolic with the light pointing into the modifier instead of directly at the subject. I covered this with the big 7-foot umbrellas in a previous post. Today I am trying this with a 60-inch octa.

To accomplish the reversing of the light I am using a device from Cheetah called a Reflective Focus-able System. This unit is a yoke-mounted speedring for your modifier and a movable rod to hold your light head and allow you to change the distance between the light head and the modifier. Here you can see I have an Interfit Photographic (this is an affiliate link, I will be compensated if you purchase directly from Interfit using my “cornicello10” discount code at checkout) battery powered Badger Unleashed strobe head mounted on the Cheetah device in a 60-inch octa.

By moving the flash head in closer or farther away from the modifier you get control over the pattern of light coming out of the modifier. If you pull the head all the way into the modifier only a small center section of the modifier gets lit and you get strong directional light, almost like a spot light, that will give you hard edged shadows. As you pull the light out farther from the modifier the light fills more of the modifier making it more larger which softens the shadow edges. It is also more diffuse, so it can bounce around the environment and open up the shadows, making them lighter in tonality.

Here are three selfies with the 60-inch octa stationary, but with the flash head adjusted within the octa. At the top the head is pulled all the way into the octa with the flash tube about 9-inches from the surface. You can see a small concentrated catchlight in the eyes and a dark shadow on the side of the nose. In the middle image the octa is still in the same position, but the flash is now about 16-inches from the back of the octa. The catchight has become larger and the shadows a bit softer. In the third image the light is pulled out to 24-inches from the back of the octa and you can see the change in the catchlights, with each panel of the octa becoming its own light, almost like a ring light. The overall light source is larger, so the look is a bit more flat and the background is a bit more open with the light being less directional.

Below is a set of images showing various configurations for the octa, starting with the standard direct mount with inner and outer diffusion panels. Then just the inner diffuser, then no diffuser. Then it gets switched to indirect placement of the flash at various distances from the octa. In all cases the light and the subject are in the same position, only the configuration of the light in the octa has changed. Power levels on the flash were adjusted to maintain the same aperture (f/13) in each of the examples. Click on the image to enlarge.

A big thanks to everyone who stopped me to say “Hi” at WPPI last week. It is always a pleasure to meet people and talk about light. Please check out the updated version of my book “Anatomy of a Studio Portrait” which is now available as either a Kindle Edition or in print.

Cheers!
John


One more time. With Cubes!

Cue the Cubes!

diffusion-cubes.jpg

Again??? Well, yes. I do these blog posts for myself as much as for my readers. They are my public notebook of lighting tests and experiments.

Here we have three exciting and vibrant still life studies in gray. All three photos were made with the Interfit Deep Zoom Reflector on their Badger Unleashed strobe head. The image on the right was with the bare reflector. In the middle I added the included diffusion sock, and on the left I added an additional layer of diffusion (double-diffused as some might say). I have identified three places in the images to look at and compare.

At point one I want you to look at the primary shadow of the gray cube onto the white cube (scroll down to the bottom of the post for larger versions of the cube photos). With the open reflector there are actually multiple overlapping shadows. The open reflector is not even across. There are multiple light sources: the flash tube, the glass dome, the walls of the reflector. Each is slightly different in brightness and casts its own shadow. Adding a diffuser homogenizes the light into one large source and eliminates the hot spot. You can see this in these photos of the face of the reflector.

Bare reflector, single layer of diffusion, and double layer of diffusion

Bare reflector, single layer of diffusion, and double layer of diffusion

Looking closely at the cubes you should still be able to see that there is a primary hard edged shadow at point One and that doesn’t change between the three photos because the overall size of the light has not changed. Remember, for a light to be softer with more gradual shadows the light has to come in from many directions. Once you have added a diffuser it won’t matter how many extra layers you add, it will not make the light any softer. The diffusion will alter the contrast of the scene as it spreads the light out in a wider pattern allowing it to bounce off of items in the environment such as the floor, walls, ceiling, etc. filling in the shadows and making them less dense. Less dense = less contrast. But the shadow edge, the quality, does not change.

Point Two is similar. The open reflector shadow is deeper. Adding the diffusion evens out the light from the reflector and fills in some of the shadow. But again the primary shadow edge is about equal.

Point Three is the most dramatic difference where the diffuser made the light larger and able to wrap around the side of the black cube to provide more illumination so you can see the back of the table top.

What I really want to concentrate on are the differences between the images with single and double diffusion. Or is differences the wrong word as they are actually very similar, almost identical in appearance. The main difference being that I had to open up the aperture a stop to maintain the proper exposure.

I hope this helps show that adding more and more layers of diffusion will not soften the shadows in your photographs. That comes from making the light larger. Multiple layers of diffusion require more light output or allow you to cut down the amount of light if you cannot power it down or don’t want to change your f/stop.

Click on each of the photos below for a larger version.

Open Reflector

Single Diffuser

Single Diffuser

Double Diffuser

Double Diffuser

Continuing the Diffusion Discussion

Size still matters

In recent posts about diffusion I have been concentrating on small light sources such as speed lights or the "standard" 7-inch metal dish reflectors on studio strobes. But what about larger sources? I was recently gifted a Speedotron 20-inch metal dish reflector. As I am no longer using Speedotrons as my main lights I adapted the reflector to an S-mount for use with my Interfit Photographic lights. This post contains affiliate links and I will be compensated if you make a purchase after clicking on my links.

As I started testing this franken-reflector I noticed that the light was harder than I expected. A look inside the bowl gave some cues as to what was going on. Speedotron lamp heads have large protruding flash tubes and/or flash tube covers. This pushes the light source out in front of the mount on the reflector, allowing the light to completely fill the bowl. The bulbs on the Interfit, though they do protrude, are not quite as long as the Speedo tubes. So most of the light was coming straight out of the flash going forward and not spreading out quickly enough to fill the bowl. 

I did some cutting and drilling to change the position of the S-mount to try to push the flash tube a bit further into the bowl. That still wasn't enough. A quick experiment using a 12x12-inch sheet of diffusion gel in the shape of a dome over the flash tube confirmed what I needed. My first thought was to find a Tupperware bowl around the size of the pyrex flash tube cover, but a quick look through kitchen cabinets didn't turn one up. That got me to thinking that people used to call some speed light flash diffusers Tupperware. And I remembered that I had a very old one of those made of a hard plastic that was specific to a speed light I no longer had. I quickly found that diffuser and a hack saw and went to work.

After cutting off the bottom of the diffuser I was relieved to find it to be exactly the right size to fit in the S-mount. A bit of hot glue and clear caulk and it was fixed in place, ready for testing. And some disappointment. The light was still harder than I expected. Even with the diffuser in place, most of the light was concentrated in the middle and not filling the bowl. Then I remembered that there was a second piece to the diffuser, a dome that snaps onto it. I quickly located that and voila, the second test did show a noticeable change in the shadows and more light "wrapping" around to the side of the subject (notice the ear is brighter). Now the diffuser was doing its job--making the light spread wider to fill the bowl of the reflector. The diffuser itself didn't make the light softer, but it did make the light source larger which did soften the light. 

The next option was to add a diffusion sock over the entire reflector. This has the effect of spreading out the light across the full 20-inches of the bowl making the light source even larger and more even across the surface. Again the diffuser spread the light and evened it out. The last test was to try the sock with and without the dome inside the reflector. This showed a subtle change. With the dome the light source appeared a bit larger, as seen by more light reaching the ear. But the shadow transition was pretty much the same with and without the dome. It was just that with the dome more of the bowl was lit and the light wasn't as directional.

Let's look at the tests (click on the image for a larger version)...

Here are side views of the interior of the modified 20-inch bowl reflector with and without the dome on the diffuser. I made one more modification, not shown here. I drilled a series of small holes around the edge of the snap on dome to help the fans in the strobe head be more efficient.

180827-cornicello-0503.jpg
180827-cornicello-0502.jpg

Safety First
IMPORTANT: DO NOT TRY THIS WITH A STROBE THAT USES TUNGSTEN OR QUARTZ MODELING LAMPS!! I was able to do this with the Interfit strobes because they use relatively cool running LED modeling lamps. For comparison, the 60-watt LED in the Honey Badger is brighter than the 250-watt quartz-halogen modeling lamp in my older strobes. But the LED's temperature after being on for hours remains around 85-degrees F while the quartz bulbs reach temperatures over 300-degrees F in a matter of seconds.


So, you might ask, what is the point of all this today. It is all part of trying to dispel myths around diffusion. It is easy to look at the photos and decide that the various diffusers changed the quality of the light. But it still comes back to the fact that the quality of the light is determined by the size of the light. In these examples the diffusion spread the light to better fill the bowl of the reflector. Without any diffusion the 20-inch reflector is bright in the middle and darker around the edges, making it appear smaller than its actual size. As diffusion is added the light spreads out to fill the bowl, making it appear to be its full size.

 

 

Light Depth

Inverse what?

In our last exciting episode, I wrote about adding diffusion to your lights. In that article I made a few references to the depth of your light and why you want to have various size light modifiers instead of moving your lights closer or farther from your subject. I promised that I would write more about this in a follow-up article, so here we are.

As noted previously, the quality of light (hard or soft), is determined by the size of the light as seen by the subject. When first starting out, you might only have one light modifier, such as a 24x30 softbox. So the temptation there is to move the light in closer or move it back farther from your subject to control the size of the light, and thereby the quality of the light. This does work. However, it has a secondary effect on your image. Moving the light changes the depth of the light.

Depth is one of the four main things I think about when designing my lighting for a portrait. The others are the depth of field that I want (how much is in focus), the size of the light (the shadow edge quality), and the amount of power I need (to get the aperture I want for the depth of field I want).

The depth of the light is based on a law of physics called the Inverse Square Law. This law states that a specified intensity (in our case, light) is inversely proportional to the square of the distance from the source of that light. As an example, if you double the distance between the light and your subject the amount of light falling on the subject will be 1/4 (at twice the distance the light has to spread out to cover 4x the area, see the illustration below). If you move the light back to 3 times the distance, the amount of light will be 1/9th the power, and so on.  

inverse-square-1
inverse-square-simplified

Another part of this law, that seems to be often forgotten or ignored, is that it applies to a point source of light, something we rarely, if ever, actually use. As you put modifiers on your lights, such as softboxes, umbrellas, or add a lens, such as in a spot light, we start drifting away from the law. So don’t get hung up on the inverse square law or on measuring the distance between your light and subject. You only need to remember one simple rule: The closer your lights are to your subject, the darker the background will be.  

OK, sounds simple enough. But it is also very powerful knowledge. With this knowledge you can take a simple white seamless paper background and make it appear white, black, or any shade of gray between them. It also allows you to light your background separately from the subject to control the apparent depth of the scene. More on that later.

So, let’s look at some examples. In this series of images the subject is 65” in front of a white seamless paper background. The single light is a 24x30 softbox. The only changes between the images is the distance from the softbox to the subject and the power setting on the light to maintain the same f/4.0 exposure. As indicated in the images, the distances are 12”, 24”, 48”, and 96”. The first thing I think you will notice is how the tone of the backdrop changes. 

light-depth

You will also want to take a look at highlights on the subject. Look at the cheek. Specular highlights are mirror-like and at first seem to not follow the inverse square law. In actuality they do follow the law, but in a reverse way. Specular highlights maintain the same brightness, no matter what the light to subject distance is, but they change in size inversely proportional to the distance. As your light is moved farther from your subject that specular highlights get smaller and appear brighter because the rest of the image is getting darker while the highlight stays the same brightness.

specular-highlights

Now, about lighting your background separately from the subject. This involves adding more lights. In this case I added one light on my white background, a flash with a 7” silver dish reflector with a red gel. With the main light (the light on the subject) 96” away from the subject you can make out a pinkish glow on the background. But when I move the light in to 12” away from the subject the white background goes to a dark gray (as shown above) and the red gel on the background light can now be seen. If I had used a dark gray or a black background paper the red would be a richer tone than the pink that you see here. The background light was on its lowest setting. If I could have lowered the power more, it would have been more red, too.

background color

A practical application: Group Photos

So far, I’ve been talking about light falloff from subject to background. We can also think about group photos and fall off from subjects different distances from the light. By combining our knowledge of light falloff with a lighting technique called feathering we can learn to light a group of people. Feathering is when instead of pointing the light directly at our subject(s) we point it a bit off so that the light skims across our subjects. A fill card (white foamcore or a pop-up white disc) helps fill in the shadows from the right side.

group-lighting-1

As an example, if our light is on the left side of our camera we would point the softbox or umbrella at the person on the right side of the group. The main intensity of the light will now be aimed at the person farthest from the light and the lower intensities from the edges of the light will be lighting the person closer to the light, helping to even out the light across the group. If the light is still too uneven, we use our knowledge of inverse square to tell us to move the light back, farther away from the group to even out the illumination across the group.

group-lighting-2

Here is a group photo of my friends at CreativeLive posing for me. This image was lit with one studio flash in a 60" Photek Softlighter on camera left and a fill card on the right. The Softlighter was backed up a bit to help even out the exposure across the four individuals.

softlighter-group-photo

That's all for today. Thank you for following along.


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Thank you for following along! If there is a photo topic you would like to see covered here please let me know in the comments section.

Cheers!
John Cornicello

 

 

Budget background projections (part 4)

Speedlights for the win!

Uh-oh! I am usually the "anti-speedlight" guy. I want my big boy strobes whenever I can. But in this episode of budget lighting solutions, I have to give props to the speedlight. In this case, my trusty old Canon 430EX II**. This is the fourth article in a short series about budget light modifiers. Here are links to the three previous posts:
Barn Doors
Spotlight effect 1
Spotlight effect 2

Today's post is about something I learned from my friend, Rick Sammon, a few years ago when I worked with him on a class here in Seattle. RIck was in town today for a presentation and he stopped by to take part in my Chair Project, so I decided to use his technique for his photograph in the series. If you get a chance, check out Rick's latest book Creative Visualization for Photographers**. 

It is such a simple and inexpensive technique that involves a speedlight, a color gel, and a piece of corrugated cardboard. Carefully cut out a pattern in the cardboard, mount the cardboard on a stand between your speedlight and the background. Light your subject so that no light falls on the background. I used my Einstein strobe head with a 36" octa for Rick's photo and I used a Westcott 12x50 strip bank for these mannequin examples. I then added my do-it-yourself foamcore barn doors from part 1 of this series) to keep the light from hitting the background (gray seamless paper).

For Rick's photo I placed a speedlight and gobo on each side of the set behind Rick and pointing at the background. I had a blue gel on one and an amber gel on the other (see the lighting diagram below). For the second photo, with Rick holding his Canon 5Ds I added a layer of textured bokeh to the image in Photoshop to give it a little different look.

This is another place that you can use Cinefoil in place of the cardboard, and can probably create more intricate patterns. But it will take more trial and error attempts to get something to look good. The first image below shows the mannequin lit by just the strip box, using the barn door to prevent the light from spilling onto the white seamless paper backdrop. Next I have set up the cardboard gobo and the speedlight with a red gel on it. In the third image I replaced the cardboard with a piece of Cinefoil in which I made some random cuts with a utility knife and changed to a blue gel on the speedlight. For these effects it appears that the closer the speedlight is to the gobo, the harder the edges of the light. If you try this out, be sure to experiment with placing the gobo various distances from the background and the speedlight various distances from the gobo. You may also need to block any light from the speedlight from hitting your subject. See the lighting diagram at the bottom of this post. 

Diagram for the photos of Rick Sammon

Diagram for the photos of Rick Sammon

Home-made cardboard gobo to create the projection on the background via the speedlight. In the photos of Rick Sammon I had one of these on each side of the set.

Home-made cardboard gobo to create the projection on the background via the speedlight. In the photos of Rick Sammon I had one of these on each side of the set.

Main light and fill card only

Main light and fill card only

Adding a projection to the background created by a speedlight, a cardboard gobo, and a red gel

Adding a projection to the background created by a speedlight, a cardboard gobo, and a red gel

Replaced the cardboard gobo with a piece of Cinefoil with holes cut in it and replaced the red gel with a blue gel

Replaced the cardboard gobo with a piece of Cinefoil with holes cut in it and replaced the red gel with a blue gel

I tried to get this to work with a strobe head, but had no luck at all. I tried an open 7" reflector and I also tried adding various grids (10-degree and 30-degree), but couldn't get the crsip look that I got from the small speedlight. Below are photos of the cardboard and Cinefoil gobos used to create the background in the photographs above. In addition to the gobos, you will need to add extra flags around them to block extraneous light from contaminating and diluting the background.

Cardboard gobo 9"x12"

Cardboard gobo 9"x12"

Cinefoil gobo 12"x13"

Cinefoil gobo 12"x13"

**This post contains affiliate links and I will be compensated if you make a purchase after clicking on my links.

Spotlight Effects on a Budget (part 3)

It's all done with mirrors

My last two posts have shown how to make home-made barndoors for your lights and how to use a sheet of foamcore to create a spotlight effect on a budget. Part three shows a technique I learned from Matthew Jordan Smith when we worked together on CreativeLive** a few years ago and it uses the same strobe head with a 7" hard dish reflector. This time we move the light around back behind the subject and use a small mirror to create the spotlight effect. This has the added benefit of providing a kicker or rim light to hightlight the hair and help separate the subject from the background. Two lights for the price of one. (**This post contains affiliate links and I will be compensated if you make a purchase after clicking on my links.)

The first image off to the side shows what the scene looks like using just the one light. Not the most flattering light for our subject. But take a small hand-held mirror and place it in front of the subject to camera left and we get the spotlight look shown in the second photograph. For these images I simply held the mirror in one hand and pressed the shutter button with the other. It would be easier to have an assistant on hand to hold and aim the mirror while you look through the viewfinder and take the photograph.

Experiment with different size mirrors. For the first photo I held up a 3x4" mirror.  For the next image I used a 5x7" mirror to light a larger area of the face. And then I moved the mirror off to camera right position to give a broad light effect. Finally, back to camera left, I covered the small mirror with black tape to just have about a 2x2" surface showing to highlight one eye.  As with the previous spotlight effect, you can add a gel over the lamp head to add color. 

At the bottom of the post is the lighting diagram for the images with the alternate (camera right) position shown in gray)

Links to previous posts in this series:
Part 1, Barn Doors
Part 2, Budget Spotlight

3"x4" mirror casts a spotlight type of effect onto the subject's eyes

3"x4" mirror casts a spotlight type of effect onto the subject's eyes

5x7" mirror

5x7" mirror

Smaller mirror to highlight one eye

Smaller mirror to highlight one eye

Mirror on camera right as a broad light

Mirror on camera right as a broad light

Adding a red gel to the strobe head

Adding a red gel to the strobe head

Examples of mirrors used for these photographs

Examples of mirrors used for these photographs

A Quick Addendum

What about silver?

This has to be one of my fastest follow ups. After a few Facebook comments, I decided to try a similar test with a silver 7' parabolic. Here is a link to the initial blog post.

Again, I used a speed light at 105mm, 24mm, and with the built-in diffuser. As the silver is somewhat "focusable," I also tried with the flash at two different distances down the umbrella shaft from the umbrella, 32" and 21". Then I followed up with the bare bulb Speedotron head at three distances, 32" 22" and 14". I didn't bother trying the 7" reflector, as I don't think I would use that in a parabolic. Here is what the light patterns looked like.

silver-parabolic-speedlight.jpg

The next test would be with a shoot-through, but I don't have a shoot-through umbrella. So I'll leave that one up to someone else.

Again, I encourage you to go and test your own equipment to make sure it is doing what you think it is doing.

Thanks!
John