light modifiers

Environmental Report #3

Comparing similar size light modifiers in light and dark environments

In a recent video I compared 7 modifiers in 9 configurations to show how they compare with each other and how much the environment affects the look of the modifiers. The modifiers in the comparison are the Photek 46-inch Softlighter II, the Interfit 48-inch folding octa, a Photoflex 45-inch reflective umbrella, a Westcott 43-inch white shoot-through umbrella, a 48-inch Parasail umbrella in both horizontal and vertical orientation, and an Interfit 32x48-inch folding softbox in both horizontal and vertical orientations.

The photos pass by quickly in the video, so I am including them in this blog post to make them easier to see.

Modifiers in a dark environment (click to enlarge)

Modifiers in a light environment (click to enlarge)

The dark environment has black v-flats on each side of the subject to reduce environmental bounce and make the shadows darker. The light environment is the same, but with white v-flats on each side to fill in and lighten the shadows. Note that the shadow edge quality is about the same in all the photos because the light sources are all about the same size. The shadow edge transition is controlled by the size of the light in relation to the subject and the contrast is controlled by how diffuse the light is and the tone of the environment.

You will also notice that all of these modifiers look pretty similar on the subject. The main difference will be in the shape of the catchlights in the eyes or on reflective objects in a still life.

Environmental Impact Analysis

Can you tell what modifier was used to make each of these photos?

This is a test, only a test. Below you will find 26 photographs of my favorite mannequin. Your assignment, should you choose to accept it, is to pair up the numbered photos with the lettered modifiers listed below.

In random order the modifiers:

environment-3-small.jpg

A. Optical spotlight
B. 24-inch square pop-up softbox
C. 1x3 strip box mounted horizontally
D. 11-inch deep zoom reflector with diffusion
E. 40-inch metallic silver umbrella
F. Snoot
G. 60-inch umbrella (Softlighter without diffusion)
H. 7-inch metal dish reflector open face
I. 11-inch deep zoom reflector with 10˚ grid
J. 42-inch white shoot-through umbrella
K. 45-inch Parasail mounted horizontally
L. 60-inch Photek Softlighter
M. 2x3 softbox mounted horizontally
N. 36-inch deep parabolic (16 rod) softbox
O. 11-inch deep zoom with 40˚ grid
P. 2x3 softbox mounted vertically
Q. 36-inch deep parabolic softbox both diffusers
R. 11-inch deep zoom reflector open face
S. 60-inch octabox
T. 45-inch Parasail mounted vertically
U. 36-inch umbrella
V. 46-inch umbrella
W. 1x3 strip box vertical
X. 36-inch deep octa with only inner diffuser
Y. 28-inch folding beauty dish
Z. 22-inch beauty dish

All of the photos were made in a black box so that the environment would not have an effect on the images (no environmental fill bouncing around the subject). Black v-flats on each side, black foamcore on the floor, and a black fabric draped across the top. The only opening was towards the light and camera. The light is in pretty much the same position and distance (4-feet) from the mannequin head. The beauty dishes were in at about 3-feet.

Click on each of the three images below to view a larger version (1097 pixels tall) or click on the links below for an even larger version (2632 pixels tall). White balance is as shot (Daylight) so you can see the color differences between the various modifiers. They vary quite a bit!

What does that modifier look like?

I had a few spare minutes yesterday (New Year’s Eve), so invited a friend and her daughter over to make some photographs with a variety of light modifiers. Here are the results of the 28 configurations we tested.

All photos lit with an Interfit Photographic Honey Badger strobe head. All photos metered to f/6.3. Subject seated about 2 feet in front of white seamless paper. All lit with the single light with no reflectors or fill light. Camera was set to “daylight” white balance (yes there is that big a difference in skin tone between them) and the only post-processing on the images was to crop them to a square.

Here is the list of modifiers used and some notes:

  • Interfit 48-inch deep parabolic softbox with both diffusers in place

  • Interfit 48-inch deep parabolic softbox with only the inner diffuser

  • Interfit 48-inch deep parabolic softbox with no diffusers (open face)

  • Interfit 48-inch deep parabolic softbox with 20-inch black foam-core disk blocking the middle of the light (looks like a ring light)*

  • Neewer 36-inch parabolic softbox with CheetahStand focusing rod with the flash head pulled all the way in to the softbox

  • Neewer 36-inch parabolic softbox with CheetahStand focusing rod with the flash extended to the opening of the softbox

  • Neewer 36-inch parabolic softbox with CheetahStand focusing rod with the flash extended to the opening of the softbox and a 20-inch black foamcore disk blocking out the middle of the light*

  • SPSystems 28-inch folding octabox with both diffusers in place Light boomed over camera on axis with lens

  • SPSystems 28-inch folding octabox with only the inner diffuser

  • 22-inch Speedotron beauty dish centered over the camera with diffusion sock

  • 22-inch Speedotron beauty dish without the sock

  • 20-inch metal dish reflector centered over the camera

  • 20-inch metal dish reflector with a diffusion sock on it

  • Interfit Deep Zoom reflector at camera left

  • Interfit Deep Zoom reflector with its diffusion sock

  • Interfit Deep Zoom reflector with 10-degree grid

  • Interfit Deep Zoom reflector with 10-degree grid and diffuser to show that the diffuser negates the effect of the grid

  • 7-inch metal dish reflector

  • 7-inch metal dish reflector with one sheet of #261 diffusion

  • 7-inch metal dish reflector with two sheets of #261 diffusion

  • 7-inch metal dish reflector with 10-degree grid

  • Interfit 2x3-foot softbox pointed directly at the subjects

  • Interfit 2x3-foot softbox feathered in front of the subjects

  • Interfit 2x2-foot collapsible softbox (which comes with the Honey Badger and has a recessed front panel)

  • 2x2 softbox with a flat front (old and apparently yellowed with age)

  • Interfit 65-inch** Silver Parabolic umbrella with the head pushed almost all the way into the umbrella

  • Interfit 65-inch** Silver Parabolic umbrella with the head pushed in (focused) and a 20-inch black foam-core disk blocking the center of the light

  • Interfit 65-inch** Silver Parabolic umbrella with the head mounted on a separate light stand about 5-feet in front of the umbrella

    * see the photo below
    **measured across the opening, other companies call this a 7-foot or an 84-inch as they measure around the back arc of the umbrella

The black foam-core disk was used in an attempt to make the lights act something like a defocused Broncolor Para. The sliding focusing arm in the 36-inch para was for the same reason. But looking at the photos, I think that I like the big 48-inch Interfit Parabolic Softbox in any of its configurations (2 diffusers, inner diffuser, no diffuser).

Some photos for clarification

Strobe head mounted on a separate stand 5 feet in front of the Interfit 65-inch Silver Parabolic Umbrella

Strobe head mounted on a separate stand 5 feet in front of the Interfit 65-inch Silver Parabolic Umbrella

Black foam-core disk blocking the center of the deep parabolic softbox

Black foam-core disk blocking the center of the deep parabolic softbox

Cheetah “Chopstick” lets you position the flash head inside the softbox, sliding it closer to or farther from the back of the softbox to focus the light

Cheetah “Chopstick” lets you position the flash head inside the softbox, sliding it closer to or farther from the back of the softbox to focus the light

What information lurks in the shadows?

Only the Shadow knows.

And he has something to say! Shadows are a very important piece of our photographs. Shadows help define our subject. They help set the mood of the photograph. They can hide things we don’t want to show. They can tell a story about how a scene was lit. And that’s what I am talking about today. What can we see in the shadows?

Here are my descriptions for the 14 images on the right (click on the image for a larger version):

  1. Standard 7-inch metal dish reflector
    Notice slight double-edge to the shadow due to the flash tube being slightly brighter than the surrounding reflector.

  2. Standard 7-inch metal dish reflector with one layer of diffusion material
    Contrast is lower from light bouncing around the room, shadow edge is more homogenized by the diffuser. The shadow edge is the same, no extra softening from the diffusion, just a brighter shadow.

  3. Standard 7-inch metal dish reflector with two layers of diffusion material
    Very similar to #2 but needing more flash power. Extra diffusion did warm up the color. Still has the same edge with no additional softening.

  4. Standard 7-inch metal dish reflector with 10-degree grid
    Narrow beam of light doesn’t hit walls, ceilings, etc. (environment), so more contrast. Still has the same shadow edge quality, just a darker shadow and restricted coverage on the background.

  5. Standard 7-inch metal dish reflector with 10-degree grid plus a layer of diffusion
    Brings us back to what we had in #1 or #2, but required 5 more stops of light power to maintain the same exposure. Don’t put diffusion in front of a grid! It negates the effect of the grid at the cost of a lot of your flash power.

  6. Deep Zoom 11-inch reflector
    Narrower light been from the deep reflector gives a darker shadow, somewhat similar to the grid in #4, but like #1 the shadow edge is doubled because of the difference in efficiency between the light direct from the flash tube and the light bounced off the walls of the reflector. Diffusion would help homogenize the shadow, but will also take away some of the contrast.

  7. Deep Zoom 11-inch reflector with 10-degree grid
    Even less environmental bounce producing a darker shadow.

  8. 1x3 strip box in vertical position
    Narrow modifier produces little shadow along its long dimension (up/down here) with much more shadow along its shorter dimension (left/right here).

  9. 1x3 strip box in horizontal position
    Rotating the narrow box moves the shadows. The left/right shadows are a little bit tighter while we now have up/down shadows. This is especially noticeable on the light stand holding the silhouette. In #8 it casts a wide shadow, while in #9 the wide pattern wraps around the narrow object and there is virtually no shadow.

  10. 2x2-foot square softbox in close at 3-feet
    This softbox has both an inner and outer diffusion panel. Shadow transition is soft

  11. 2x2-foot square softbox backed up to 6 feet
    The box gets smaller in relation to the subject when moved back.The shadow gets a harder and more defined edge. The background brightens up slightly (depth of light, inverse square law). More light bounces around the room picking up some warmth from the wooden floor.

  12. 2x2-foot square softbox at 6 feet with an extra layer of diffusion
    Shadow quality remains the same, but image picked up some warmth from either the wood floor bouncing in or from the diffusion material (or both). Requires more flash power.

  13. 46-inch Photek Softlighter umbrella WITHOUT the diffuser
    Large, round light. Even shadows all around. Background is brighter than #14 due to longer light path and depth. Although the umbrella is 36 inches from the subject, the light path is from the flash to the umbrella (24-inches) and from the umbrella to the wall (36-inches) so the distance of light is like having a forward facing light at 5-feet away instead of 3-feet, as you would get with the front diffuser (see #14).

  14. 46-inch Photek Softlighter umbrella with the diffuser
    Adding the diffusion cover has a slight effect on lightening the shadow density. Background is slightly darker as the light source (the diffusion panel) is closer to the subject. The closer the light is to your subject, the darker the background will be.

All the photos were metered to give the same exposure. In most cases the aperture remained the same (f/4.0) and the flash power was adjusted to maintain correct exposure. The exceptions are the exxamples with the Deep Zoom reflector, as it was very efficient and I could not lower the flash power enough so I had to stop down the lens to f/7.1. 

The main take-aways from this lesson is that the shape of your modifier determines the shape of the shadows and the size of the light as seen by the subject determines the size of the shadow width or the quality of light, that is hard or soft. Diffusion, along with the environment, controls the shadow density or contrast. Adding diffusion directly to a light, where it doesn’t make the light any larger, does not soften the light. It is a very subtle, but important concept. Diffusion does homogenize the light, making it more even across its field. And, depending on the environment, fills in the shadows making them less dark by bouncing off the walls, floor, ceiling, and other surroundings. Don’t confuse contrast with quality.

As I said, the difference can be subtle. Here we have three photos to compare. The first (A) was lit with a standard 7-inch diameter silver metal dish reflector. It casts a hard edged deep shadow. Next, I taped a sheet of diffusion material over the reflector (B) and you can see that the edge shape and transition (quality) has remained the same. What changed was the depth or darkness of the shadow (contrast). The diffusion spread the light around the studio and made the shadows lighter in tone, but the edge didn’t change because the light size didn’t change. For the third photo (C) I switched to a 20-inch diameter light modifier without diffusion and you can see here that the edge got softer and the transition got wider as the light was able to “wrap” around the subject for a softer light quality.

contrast-vs-quality.jpg

Now let’s look at what happens when we keep the same small 7-inch diameter reflector but add single and double diffusion. The first sheet of diffusion material makes the shadow brighter and also homogenizes the shadow edge so there is no longer a double-shadow (from the flash tube and the reflector not being equal in brightness). Adding the second layer of diffusion slightly lightens the shadow, but not appreciably. It does not in any way soften the light.

multi-diffusion.jpg
triple-diffusion

I can anticipate a comment and question. That’s all well and good for diffusing a small light. I am using a Photek Softlighter and want to double (or triple) the diffusion on that. What happens there? Let’s take a look! Here are four examples starting with the Softlighter umbrella on its own without the diffuser. Next is with the diffuser. Then for double diffusion I hung a roll of diffusion material in front of the Softlighter to double-diffuse it. Then I doubled that up to make it triple-diffused (see the photo on the right). Adding the diffusion panel to the bare umbrella actually limits the spread of the light and makes the shadow a bit darker. Adding additional layers of diffusion on top of that brighten the shadows ever so slightly and start to add some warmth to the color. But again, no change in the quality/softness of the light from extra diffusion. The size of the light remained the same.

This environmental bounce can also cause color casts if the room isn’t neutral in color. In a larger studio, or in a studio with black walls, ceiling, and floors, or in an open field the changes in contrast on the subject with or without diffusion and grids will be much less noticeable.

 

 

Well, this brings us to the close of another year. 2018 has been quite a year for me. The biggest event was the passing of my 98-year-old mom, Rose, in August. Thanks for everything you have done for me and for all the support for my taking my own direction in life. I could not have had a better mom. Rest in peace.

So, here is looking to a bright new year with new challenges and accomplishments. I wish you all a Happy New Year! Stay safe and be well.

Cheers!
John














Parabolic Umbrellas

Getting the most from your parabolic umbrella

It has been a few years now since Paul Buff (Alien Bees) introduced their 86-inch PLM (Parabolic Light Modifier) umbrella, which was quickly followed up by similar umbrellas from other companies. Some call them a 7-foot umbrella (measured across the arc of the back of the umbrella), some call then 65-inch umbrellas (measured across the opening of the umbrella). They come in a variety of styles—white reflective, dull silver, shiny silver, and translucent (shoot through). They have 16 ribs/panels (most photo umbrellas have 8, while the Photek GoodLighter and Softlighter have 10). The more ribs, the closer the shape comes to being round.

But it is not just about the shape (mostly noticed in the catchlights of people). Before all of these inexpensive parabolic umbrellas there were others at much greater price from companies like Broncolor and Briese. I believe it was all started by Briese, but their market is mostly in the film industry. More photographers around the world are familiar with the Broncolor Para modifiers that come in a variety sizes from their Para 88 (about 3-feet across the front) to the Para 330 (almost 11-feet across the front opening). Prices range from $3,000 to $7,000 or more just for the umbrella system.

These original parabolic reflectors provide a wide range of looks by having a mechanism to move the lamp head within the umbrella to focus or defocus the light. With the lamp placed deep into the umbrella you can find the focus spot that turns it into a gigantic spotlight that collimates the light rays emerging from it. But many people feel that the real beauty from the para comes when it is defocused. To do that bring the lamp head all the way out to the edge of the umbrella. With its 24 shiny silver panels the center of the umbrella goes dark and you wind up with 24 small bright spotlights around the edge, making it into a gigantic ring light.

It is this soft, yet hard, ring light quality that I have found to be lacking in the 7-foot class parabolic umbrellas. For most of the time that I have owned these big umbrellas I have basically used them as umbrellas for fill light or with a heavy diffusion fabric across the front turning them into big round softboxes. That is fine for the white reflective and the translucent umbrellas. But that silver umbrella. There had to be more to it.

For the photos in this article I will be using the shiny silver version of the Interfit Photographic 65-inch Parabolic Umbrella with their Honey Badger studio flash. You can slide your lamp all the way in on the shaft of these umbrellas to create a strong spotlight like effect. But drawing the head out to the end of the shaft doesn’t get to the ring light look. Take a look at the first two photos of the silver umbrella with the head all the way in making for a concentrated light and then with the head pulled out to the very end of the shaft. The center is still the hot spot in the umbrella. Where are those spotlights around the edge of the umbrella?

Flash head mounted far down the shaft of the umbrella

Flash head mounted far down the shaft of the umbrella

Flash head mounted as far out on the umbrella shaft as possible

Flash head mounted as far out on the umbrella shaft as possible

Flash head mounted on a separate stand 5-feet out from the umbrella

Flash head mounted on a separate stand 5-feet out from the umbrella

para-compare.jpg

For a while I’ve been thinking about ways to make these umbrellas act a bit more like the Para. I don’t expect to match it exactly, but I was sure that I could do better than what I’ve been getting. It finally dawned on me to take the lamp head off of the umbrella shaft and mount it on a separate light stand so I could pull it even further out of the umbrella. Take a look at the light pattern in the umbrella in the third photo where I have placed the lamp 5-feet (60-inches) from the center of the umbrella instead of at the 31-inches when mounted on the umbrella shaft. This is starting to look more like what I’ve been trying to achieve. The edge lights are not quite as small as I would like, but I think that comes from the overall shape of the umbrella. The true paras are deeper and more of a cone shape than the 7-footers.

What does all that translate to on the other side of the camera? Here are three self portraits made with the lamp head in the three positions. The modifier and camera remained stationary between these photos with the umbrella about 8-feet away from the subject and white seamless paper about 2-feet behind the subject.

Flash head mounted far up the umbrella shaft

Flash head mounted far up the umbrella shaft

Flash head pulled back to the end of the umbrella shaft

Flash head pulled back to the end of the umbrella shaft

Flash head mounted outside the umbrella

Flash head mounted outside the umbrella

head-outside4.jpg

The first image feels a bit harsh and contrasty for my taste. The second is a little nicer with a bit more of a feeling of the light wrapping. Third image is my choice for contrast and quality. Notice the color change in the third photo. In the first two images the light is pretty well contained within the modifier and doesn’t bounce all around the room (what I call environmental bounce). In the third image the flash head is well outside the modifier, as shown on the right, bouncing light around the room which has a golden colored wood floor, which becomes a secondary light source, which warms up the image considerably.

Here are closeups of the catchlights in each of the above. Some might find the ring light look in the third image distracting. Other people might not ever notice it.

With the lamp head way out in front of the modifier you need to be careful about the light striking the front of the lens causing flare. The lens hood might not be enough. You might need to set up a flag between the light and the lens depending on how close you are trying to get the light to your subject.

You can stop reading here if you like. But if you want to geek out a bit about parabolas, I’ve added the following section.

Going more into the geek…

Let’s look at what makes a parabola. First the standard definition: a symmetrical open plane curve formed by the intersection of a cone with a plane parallel to its side. 

WHAT???

parabola-focused.jpg
parabola-defocused.jpg

Basically, it is a U-shaped curve. You can read tons more on Wikipedia. Here we are concerned less with what a parabola is or how it is formed, but more about what it does to light. Within the parabola is a focus point on the axis of symmetry and outside is a line called the directix. The parabola is the shape defined when all the points on a line are equidistant from both the focus point and the directix. Visually, it goes something like this on the right.

When talking about light, a (theoretical) point source placed at the focus point is reflected into a parallel beam, leaving the parabola in parallel rays. In actual practice let’s just say that the light is deep (falls off slower than inverse square would predict) and contained or directional. Various factors prevent the light rays from being truly parallel. There is little environmental bounce, so the light is contrasty, but it is also large, so it fills in some shadows. You will need to experiment with having the light at different distances from the subject to find the look that you like.

If the lamp is moved further out of the parabola—defocused—the light rays are scattered (diffused) and exit in a diverging pattern, but the center goes dark and you get a ring of bright spotlight-like lights around the edge of the reflector. The overall exposure will be less as more of the light is spread out and bypassing the subject. Again, experiment with different light-to-subject distances, erring towards having the light closer in the smaller the parabolic umbrella you are using.


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

Color My World

So your light provides accurate color, what about your modifiers

I recently posted a self portrait I made while testing the new Interfit Studio Essentials LED monolight. I got some comments about how good the color looked and asking if I did much color correction on the image. I actually did very little color work on the image (shown here). I made one frame with an X-Rite Color Checker Passport and the second frame without. Using Adobe Lightroom Classic's white balance picker, I clicked on the middle gray swatch on the Color Checker and that made a small change, -100K and -5 tint. I thought the image was a bit too saturated, so I also pulled down the vibrance slider -11 points. That was it. 

Image straight out of camera with no color adjustment

Image straight out of camera with no color adjustment

Image straight out of camera, no color adjustments

Image straight out of camera, no color adjustments

Image with minor color corrections (temp -100, tint +5, vibrance -11)

Image with minor color corrections (temp -100, tint +5, vibrance -11)

Or was it????

That got me to thinking about the modifiers I have available. I see so much concern over the color accuracy of strobes, fluorescent lamps, and LEDs. But not so much talk about the modifiers. With so many types and brands of modifiers I figured there must be differences. And I was right. Sometimes big differences.

For the above photos I used two LED monolights on me each with an Interfit 1x3-foot strip box. The light on the background was a Honey Badger studio strobe at its lowest power setting. I was quite happy with the results. But what about my other modifiers.

I grabbed a few modifiers: 7-inch silver metal dish, 24-inch pop-up that comes with the LED monolights (and also with the Honey Badger), a 20-inch metal dish reflector, the same reflector with two different diffusion socks, a 22-inch white beauty dish, a Photoflex 42-inch umbrella, a Photek 46" umbrella (a Softlighter without the diffuser), a Westcott 40-inch shoot-through umbrella, a Westcott Apollo Orb, an Interfit 1x3-foot strip box, and a 32" Photoflex white translucent pop-up diffuser panel. I set the camera (this time a Canon EOS M5 mirrorless with the 70-200 f/4 IS lens. AV mode at f/4.5. 

The first set of images shows have no corrections, just as they came out of the camera. For the second set I used the White Balance eyedropper to balance on the middle gray patch. I also attempted to get the exposure evened out between all of the modifier images (click on each image for a larger version). Quite a variety of colors!!

Samples from each modifier straight out of camera with no color adjustments

Samples from each modifier with color and exposure corrections 

With the camera set to Daylight White Balance, Lightroom read it as 5000K and +9 tint. Here is a list of the color corrections for each modifier:

7-inch silver dish: 5050 (+50K) +1 (-8)
24-inch popup: 4900 (-50K) +13 (+4)
20" dish: 4800 (-150K) +15 (+6)
20-inch + speedotron diffuser: 4450 (-550K) +6 (-3)
20-inch = mola diffuser: 4250 (-750K) +14 (+5)
Beauty dish: 5200 (+200K) +10 (+1)
Photoflex umbrella: 4900 (-50K) +4 (-5)
Photek umbrella: 4820 (-180K) -1 (-11)
Shoot through umbrella: 4800 (-150K) +8 (-1)
Apollo Orb: 5000 (0) +14 (+5)
Interfit strip bank: 4900 (-100K) +14 (+5)
Photoflex disc: 4650 (-350K) +4 (-5)

For reference, a +K value added yellow, -K added blue and +tint added magenta and -tint added green.

Have you done a comparison of the effects your various modifiers have on your lights? 

I have.

Thanks for playing along...
John

 

 

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.

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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.