speedlight

Diffusing on-camera flash

What does diffusion on a speed light do?

I keep seeing photographers talk about diffusing their on-camera flash. Whether it be with a handkerchief, a Stofen diffuser, the built-in pop-out diffuser panel, or some other form of diffusion taped over the light, I am not quite sure what they are trying to accomplish. These various diffusers are used to spread out the light coming out of the flash, basically to allow the flash to be used with a wider angle (shorter) lens. The light spreads out to cover more of the scene at the cost of loss of power. 

Quality or character of light?
Some that I talk to say that they use the diffusion to soften the light--to make it look better. I question this. We are talking about diffusion methods that pretty much keep the flash the same size as it is without the diffuser. We should all know that to make a light softer you have to make it larger in relation to the subject it is lighting. A larger light source provides light from more angles allowing it to become its own fill light to soften the edges of shadows. There are devices like the Gary Fong diffusers or the Roque Flash Benders that do make the light larger. I am not talking about those here. Just diffusers like those shown here...

Straight flash, diffusion material taped over flash, and Stofen Diffuser on flash

Straight flash, diffusion material taped over flash, and Stofen Diffuser on flash

Here are two photos of my favorite mannequin (models are hard to come by in the middle of the night when I get inspired to write these blog posts). One photo was made with the straight flash and the other was made with the 1-stop diffusion material taped over the light. Can you easily tell which is which? All of the photos were made in TTL mode at +/- 0 stops with no post-processin except for white balance. 

Two more examples, with a longer lens...

I am not seeing it
My argument is that diffusion right on the speed light, which doesn't make the light source significantly larger, does not soften the light. The only slight exception might be if the wider distribution of the light allows it to bounce off a low ceiling or close by light color walls. But even that will be extremely subtle. To me, these methods of diffusion only do a few things, none of them beneficial. They make the flash have to work harder, putting out twice as much light (1 stop), while increasing recycle time and draining battery power. 

Look closely at the shadows in each of the photos. A softer light creates a softer, more gradual transition from the true value of the subject to the underexposed shadow areas. In these photos the shadow edges look the same. There is no softening of the light. 

What is your experience with diffusion and speed lights? In the above examples, photos labeled B (on the left) have the diffusion in place. Photos labeled A (on the right) are straight flash. Is there enough difference between A and B to justify the loss of light power and the extra drain on batteries? 

Index card diffuser

Index card diffuser

But, but, but...
OK, you say. These are close in portraits. What about something more like at an event or reception. Here are six photos taken with an on-camera flash with a 28mm lens about 11 feet from camera to the subject (me!). Straight on flash, diffusion material over the flash, the built-in diffusion panel, a Stofen pointed straight ahead, the Stofen with the flash pointed up at the ceiling, and with a white index card taped to the pointing up flash. This time I did not correct the white balance, these are all "out of camera." All TTL exposures at ISO 400 and f/5.0.

This post is not anti-speed light. I think you can get some very nice light from speed lights--even when mounted on the camera's hot shoe. The following photos were all made using an on-camera flash that was pointed off to the left to bounce off a wall, effectively making the light much larger and thereby softer. 

bounced-flash-1
bounced-flash-2

American Speedlight Corporation (ASCOR)

We've come a long way, my friends

Many, many years ago I worked as a photo assistant in New York City. In 1979 I started at a catalog studio on West 23rd Street between 10th and 11th Avenues. Yes, that is where the New York High Line is now. Back then it was an abandoned elevated train track full of weeds and dead birds. In that studio we primarily used Mole Richardson hot lights to photograph things like ceiling fans and large room sets for Montgomery Ward and other similar retailers' catalogs.

Hot Lights!

These were 750- to 2000-watt hot lights. Within the first few days on the job you quickly learned to have a pair of leather gloves hanging from your belt along with some wooden clothespins to use when adjusting the lights. Ouch! And the lights were often mounted on large boom stands that had big maroon color counterweights on one end of the boom arm. Somehow, one of those counterweights, at about forehead level, often managed to find its way to a spot between the elevator and the light switch. Ouch! 

There was a fashion studio on one of the floors, though, that used electronic flash. Balcar was the brand. I don't recall if they were 1200 or 2400 watt second packs. But I do remember the small rectangular plugs that had a habit of arcing. One day the photographer I was working with, who was a bit ditzy, decided to change a head by himself. Unfortunately, I was standing next to him and he unplugged the light as I was yelling at him to turn the power off first. BANG! Lost my hearing for an hour or two. Luckily he didn't electrocute himself.

And that brings me to the subject of this post. My buddy Tony left this studio to go work as a photographer at another studio over on 7th Ave between 25th and 26th street. Shortly after that he brought me over there as a still life product photographer, too. This place was more modern and we used Speedotron 2400 watt-second packs and heads. (As an aside, I still have a Speedotron 2401A pack and one or two model 105 heads that still perform great. I even have a Dyna-lite D804II that is probably 40 years old and still going strong. See the photo below of these units alongside a modern Interfit strobe.) 

Speedotron 2401A and Dyna-lite D804ii pack & head systems, along side an Interfit S1 (self contained, including battery, no A/C power required, but optional).

Speedotron 2401A and Dyna-lite D804ii pack & head systems, along side an Interfit S1 (self contained, including battery, no A/C power required, but optional).

This studio also had a fashion studio, but it had these monster ASCOR Series 800 Sunlight strobes (which ASCOR called speedlights, noting in the instruction manual that strobe was a misnomer, as strobe implies repetitive flashing).

The ASCOR Sunlight

I have to assume that most of my readers might not have any idea what these Sunlight units were like. So, I will quote some things from the instruction manual for these monsters. Before that, I just want to add that almost everyone I talk to who was familiar with these speedlights mentions needing to keep a wooden broomstick nearby just in case they had to pry someone away from the unit in the case something went wrong.

So, from the user manual, dated around 1955...

"ASCOR has long stood for the best in electronic flash. The company (starting as Parker & Young and the trademark Fotolux in 1946, changing to American Speedlight Corporation in 1948) has, from the beginning, specialized in building the most advanced types of speedlights for exacting professionals."

"The tremendous number of speedlights in all shapes, sizes, and prices exhibited at recent photo shows leaves even the electronic flash engineer confused. With all the claims, counter-claims and partial information, it is no wonder that the dealer is wary...think of the poor customer...it is amazing that so many have the courage to buy. What is sorely needed are a few simple facts that can be used as a basis of comparison."

Not much has changed

Wow, not much has changed since the 40s and 50s. The manual then goes on to talk about guide numbers, and the "serious faults" in using guide numbers. 1. high guide numbers can be achieved by concentrating the available light in a narrow beam from the reflector, which results in uneven coverage or hot spots. 2. a guide number can honestly be chosen over a wide range, depending on how the film is developed, the latitude of the films, etc. 

They next talk about watt-seconds, "For too long most people have rated speedlights in watt-seconds. Just what is a watt-second? If you really know, you are one of the unusual photographers. Then again, what photographer really cares? Watt-seconds is not a rating of light output of speedlight equipment. The use of watt-seconds, microfarads, and other terms has so confused the photographer that many are thoroughly baffled about electronic flash."

How do you compare lights?

So, what are the points of comparison between various studio strobes? "Speedlight is just light." Photographic effectiveness comes down to...

  1. Strength of the light

  2. Color of the light

  3. Coverage of the reflector

  4. Speed of the flash or exposure

  5. Recharge or recycling time of the equipment

"The ASCOR Speedlight (ASCORLIGHT) is an electronic device for converting electrical energy from a relatively small power source into a high-speed, high intensity flash of light. Essentially, the energy is drawn slowly from the power line or battery, converted into hight voltage, and stored in a capacitor (an electrical storage tank). Then at the moment the flash of light is desired, the energy is dumped instantaneously out of the capacitors through the flashtube (watt-seconds) which converts the electrical energy into light."

Enough of the boring stuff. What I really wanted to point out was the size of the units and the simplicity of operation. The manual then lists 23 important features of the ASCORLIGHT SERIES 800. Things such as "from 800 to 40,000 watt-Seconds" and "Economical (average power drawn is less than drawn by a 200-watt light bulb." But the one that really stands out to me is #22: "Designed for One Man Operation and Portability." Keep the word portability in mind as it then lists the specifications.

Portability!?!?

ASCOR A801 power supply with 4 800w-s conders

There were two power supplies available. The power supply is the control unit and does nothing on its own until you add condenser (capacitor) units to it. The Sunlight Maste Power Supply A801 weighed 85 lbs. The Super Master Model A805 weighed in at a svelte 355 lbs! The A801 dimensions were 9-38"H x 12-1/8"W x 21-3/8"L. The A805 was 42"H x 22"W x 17"D. Remember, designed to be "portable." And this is just the power supply.

In addition to the power supply, you need condensers. Each condenser stores 800 watt-seconds of power and each weighs in at 60lbs. These are metal boxes filled with oil as the dielectric element. Slightly smaller than the A801 power supply, each condenser was 9-3/8"H x 8-5/8"W x 21-3/8"L. Remember, "portable." And we still haven't added a flash head and the required cables. The manual doesn't list the weight of the heads, but they were pretty substantial. If I remember correctly, the flash tube was around 9" long. The standard head reflector was 14" across and other reflectors were available from 9" to 24" across. And we still haven't added the light stands, which could range from 10 to over 100 lbs each. The model 503 flash head could handle up to 3200 watt-seconds of energy. The model 623 head used a model FT623 flash tube, and could handle up to 45,000 watt-seconds and could be attached to forty-eight (48!!) condenser units. 48 metal boxes, weighing 60 lbs each. That is almost 1-1/2 tons of lighting gear for one flash head!

Guessing that there are about 20 condensers ganged up here for 16,000 watt-seconds of power. Each condenser is oil-filled and weighs 60 lbs.

You are advised to "Stack the model A802 condenser units on the Type 3200 Dolly (M251) which is designed to hold six condenser units. Place the Platform Adapter M261 on top of the condenser units, this Platform Adapter will fit down over two condenser units placed side by side. If the model A801 Power Supply is to be used, it is placed on the Platform Adapter." At least the dolly has wheels (portable!). Then you took these very thick 3-foot and 6-foot cables and plugged them in between the power supply and condenser and then between each additional condenser and then plug the 25-foot cable to the flash head into the end of the chain. Then use dummy plugs to seal any condenser or power supply connectors not being used.

"Next, connect the Power Cord AC, D102, to the power supply outlet and plug it directly into any 117 volt 60 cycle AC source, "NOTE: MAKE A SOLID CONNECTION OF AC CORD: If a flimsy connection of the AC cord is made this condition can cause trouble. A momentary interruption of the power will cause the discharge relays to make contact. If the power is then applied before the capacitors are allowed to discharge, and arc can be started, which can damage the relays and the discharge resistors. The third wired should be attached to a ground." In total, there are 15 steps (each a paragraph) involved in turning on the unit. Step 15 is to plug your camera sync cord into the end of the sync cord which is connected to the power supply. Flash the unit by tripping your camera." Whew! Portable and fast operation. 

They then talk about strobing or repetitive flashing. That is done by "firing several speedlights successively with the ASCOR Strober, each unit powering its own set of lights. The operator can vary the speed of flashing and ONE POWER UNIT IS REQUIRE FOR EACH IMAGE DESIRED ON THE FILM." Emphasis mine. You want 10 images of the swing of a tennis racket? That means 10 power supplies and at least 10 condenser units. At least you could attach two lights to each condenser unit. A spider box was available if you wanted to use three heads. 

Many of you might have heard of sync voltage of older flash equipment and the damage it could do to digital cameras as the current goes through the shutter contacts. Well, ASCOR took care of that way back when. "ASCORLIGHT units use an electronic tube in the triggering circuit or sync circuit which directs the current through the flash tube--not into the shutter contacts. NOTE: Here we have incorporated ANOTHER SAFETY FEATURE to prevent electrical damage to the shutter contacts and to personnel."

For my friends such as Tony Corbell and Matthew Jordan Smith who live by the light meter, I should mention flash meters here. Take a look at this page from the ASCOR manual that pictures the M333 General Radio Light Meter in use. Might be why Joel Grimes says he doesn't want to know what a flash meter is. It is bigger than my cameras.

So, how much light did these monsters put out? The manual claims that using one condenser (800 watt-seconds) at 6-feet using the standard reflector would give you F/22. They don't list an ASA or ISO number, but earlier refer to daylight Ektachrome. I don't know the ASA rating for 1950s Ektachrome. However, they do provide a nomograph that says at ASA (ISO) 100 the guide number for one condenser would be about 400. So that is F/40 at 10 feet. 

The Interfit S1 has 500 watt-seconds of power and weighs in at a little over 6 lbs.

A modern flash, like the Interfit S1 that is 500 watt-seconds gives me f/18 at 10 feet with the standard 7" reflector. That is 2-1/3 stops more light with the ASCOR (which was rated at 800 w-s), and which has a brighter, more focused reflector. It is also with the ASCOR weighing in at close to 160 lbs plus a heavy-duty light stand, while the S1 weighs in at 6.3 lbs and is battery operated. We have a very different view of "portability" now. 

I am sorry, but I don't know who to credit the photos of the ASCOR equipment to. If these are your photos, may I please ask for permission to keep them in this blog post?

If you used these ASCOR lights and have any stories about them please share them in the comments here. We've come a long way since these units from the 40s. Let's keep some memory of them alive.

Thanks!
John

 

 

 

Hummingbirds in Sequim

Let's try something new!

competing hummingbirds

As previously mentioned, I was out in Sequim, WA last week to teach a lighting workshop. I stayed overnight at a friend’s place and about 15 minutes before we had to drive over to the workshop I decided to try to make a photo of some hummingbirds flying around the deck. I grabbed one of my Interfit Photographic S1 battery operated strobes out of its case along with its standard 7” reflector and a light stand. I set it up about 3 feet from the bird feeder and then popped a Canon EOS M5 camera onto a tripod with the 70-200mm f/4 IS L lens and a cable release. In just a few of minutes I captured some photos and then had to quickly pack up and head to the workshop (more on the workshop coming soon). For these the flash was in manual mode with the power dialed down to its lowest setting (2.0). The S1 uses IGBT technology* to control the flash, so dialing down gives the shortest flash duration to help avoid motion blur. The camera was also in manual mode and the settings were ISO 100, Shutter speed 1/160, and aperture f/6.3

No, these aren’t the best hummingbird photos. If I were to do this again I would give myself more than 15 minutes and would use at least 2, possibly three, lights for more dimensionality. I would also set up a backdrop behind the birds (where the third light might be used). Here the backdrop was a stand of dark trees about 60 yards away that went completely black. For this morning I was mostly interested in seeing if the flash could capture the wings of the hummingbirds and I think they did well. 

In lieu of the mediocre photograph, let’s make this a learning experience.

High Speed Sync?
Some might ask why I used normal sync at 1/160 shutter speed instead of putting the flash into High Speed Sync (HSS) mode. In my experience, HSS is great for matching the flash to the ambient light to photograph at larger apertures (f/4 to f/1.2) to get limited depth of field in an outdoor flash photograph (I didn't need that here, I actually wanted a smaller aperture for more depth of field). But it doesn’t help with freezing motion. Here is a series of photos made with a Canon 430EX II speedlite in normal and HSS modes where you can see what happens to the motion using HSS to photograph a spinning fan.

Notice that at normal sync speeds, even as slow as 1/15 second, the flash duration is fast enough to freeze the motion of the spinning fan blades. As long as the room is dark enough, the ambient light won't affect the photo and the short flash duration becomes your effective "shutter speed" even if the shutter is open for a full second or more. When you get into the HSS zone there is a lot of blur, even though the shutter speeds are faster.

How Flash and Shutter Speed Sync

If you are not familiar with High Speed Sync, what it does is pulses the flash rapidly during the exposure to enable it to synchronize with the moving blades of your camera’s shutter. In normal sync mode you press the shutter button, the first curtain of the shutter opens, the flash fires, then the second (rear) curtain closes. When you go above your camera sync speed (which could be anywhere from 1/60 to 1/250 second) the first curtain opens, the second curtain starts to close, then the flash fires.

With the shutter speed set at or below the sync speed

Shutter speed is set higher than the sync speed

flash sync black band

If you are just a step or two above your sync speed you get a dark band across one edge of your photo. At higher speeds the flash doesn’t register at all, as the second curtain starts closing as soon and fast as the first curtain opens. 

High Speed Sync fires a series of lower powered flashes in perfect synchronization with the moving curtains so that the image looks like it was made with one flash.

How flash and shutter speed sync with each other. Click on the image to view it larger.

Downsides to High Speed Sync

The series of flashes, while being great for letting you photograph at wide open apertures, does have some downsides. The most noticeable is the reduction in power output. Normally the strobe fires and needs a second or two for the capacitors to recycle and be ready to fire again. In HSS the flash doesn’t have any time for recycling, so it puts out a series of very low powered flashes. The light usually has to be close to your subject. You will lose a stop of power every time you double the shutter speed above the sync speed. The second downside is that it doesn’t help much with freezing action. Third is that it goes through batteries quicker. And fourth is that over time the rapid flashing can lead to a lower life expectancy of the flash tube. A note on that, though, is that I have some studio flash units here that are close to or even more than 40 years old and the flash tubes are still working on them (but they’ve never been used for HSS, which didn’t exist 40 years ago). 

*IGBT = Insulated Gate Bipolar Transistor
Different flash technologies go about controlling power output and flash duration differently. Large studio pack and head systems usually control power by switching banks of capacitors on or off (capacitor switching). Lowering the power on the pack will shorten the flash duration.
Until recently, most monoblock strobes would vary the voltage of the capacitors (voltage lowering) to control power. In these lowering the power leads to longer flash duration with some change in the color temperature of the light.
IGBT units have constant voltage, but have the ability to shut off the flash tube (tail trimming) when the desired amount of light has been emitted. Here flash duration gets faster as the power is decreased. Color temperature should be a little more consistent at different power levels and by cutting off the tail of the flash the ability to freeze motion is increased. When using IGBT flashes, going to half power or lower gives the faster flash durations. 

DISCLOSURE: I am part of the Interfit CreativePros Team

 

Understanding High Speed Sync

It isn't about stopping motion

A few days ago I was having a conversation with another photographer and they brought up the idea of using high speed sync flash to stop motion. If I remember correctly, it was in regards to photographing liquid pouring out of a bottle into a glass. That got me thinking that the concept of hight speed sync (HSS) sounds like it might help, but that really isn't true.

Let's start with what HSS is. It allows you to sync your flash with shutter speeds above your normal sync speed so that you can use larger apertures for shallower depth of field or so that you can control the exposure on your background when working outdoors in full sunlight. A big minus is that HSS eats a lot of power and lowers the output of the flash and it eats through batteries (not an issue if you have an a/c powered flash).

What HSS does not do it help freeze motion. The two things that can help freeze motion are a fast shutter speed and/or a flash with a very short flash duration. High speed sync does let you use a faster shutter speed. But you no longer have a single fast flash burst. Instead, when your flash is in HSS mode it fires a number of times in rapid succession in sync with your camera’s shutter. The flashes are too close together for your eye to register them separately, so to your eye it looks like one flash, but it is actually strobing. At full power your speed light might take 1 to 3 or more seconds to recycle between flashes. In order to flash that many times in the short timespan of your shutter speed the flashes are relatively weak to allow the immediate recycling of the flash. 

To show this, I’ve set up a couple of very basic experiments with a speed light and a Paul C. Buff Einstein studio flash (which offers an “action” mode with a very fast flash duration). Nothing very fancy, it is just an ordinary personal size desk fan, a camera, and a light. As a control, the first image is taken without any flash. It is lit by window light with the ISO cranked way up (256,000) to allow for a shutter speed of 1/4000 second. You can clearly see that 1/4000 of a second was not fast enough to freeze the blades on the fan.

Next is a series of images lit by a Canon 430 EXII speed light, off camera, connected by a remote cable. The first two images are taken at 1/5 of a second and 1/200 of a second (normal sync mode) and you can see that the flash did a fairly decent job of freezing the blades of the fan, but not quite good enough to make the label on one of the blades readable. 

The next image is at 1/400 second, putting the flash into high speed sync mode. As you can see, it did a much worse job at freezing the blades of the fan. The next image moves the shutter speed up to 1/1250 of a second in HSS mode, and still a big blur. Even at 1/4000 of a second in HSS mode the label is a blur.

Compare the images at 1/4000 of a second with and without flash.

Very little difference in stopping action with or without a flash at 1/4000 of a second.

Very little difference in stopping action with or without a flash at 1/4000 of a second.

Now switch to the Einstein flash. The first two images have the Einstein in “color” mode which is intended to provide consistent color between flashes at the expense of a longer flash duration. You can see that at 1/2 second and at 1/160 of a second the label on the fan blade is not readily readable. 

Changing the Einstein to “Action” mode to provide a shorter flash duration gives us the last two images, made at 1/2 and 1/160 second. Even these have a blurred label, but much sharper than the images made with high speed sync at 1/4000 of a second. 

Now, I’m sure that most of us don’t have much occasion to photograph spinning fans. But we do sometimes get called on to photograph a liquid being poured. Does HSS help in this situation? I hope that you have already guessed the answer based on what you have read here so far. But let’s look at some images.

This time I will start with two using the Einstein. Each of these is at 1/2 second in “color” mode and in “action” mode. Both do a decent job of freezing the action of the pour and the bubbles.

Compare the above to the following images made with a speed light. The first one is at 1/60th second (normal sync) with good motion stopping. Next is at 1/500th second and we see that it is underexposed by a stop or two. Even with the flash being about 18-inches from the glass, it doesn’t have enough power to give me f/11. So, for the next image I bumped the ISO up from 100 to 400 to get a better exposure. Note that the action stopping is pretty much the same as at 1/60th of a second, at the cost of more noise due to the higher ISO (or you could give up depth of field and use a wider aperture—another tradeoff). Next I go to 1/2000 of a second, losing more power, but not gaining much, if anything, in the ability to stop action. 

Here are two pour photos side by side. One is lit with a speed light in high speed sync mode at a shutter speed of 1/2000th of a second. The other is lit by an Einstein flash in normal sync mode at 1/60th of a second. Can you see much difference in them? Can you tell which one is at 1/2000th of a second?

One of these pours is lit with a flash in normal sync at 1/60 of a second. The other is lit with a flash in High Speed Sync mode at 1/2000 of a second. Can you tell which is which?

One of these pours is lit with a flash in normal sync at 1/60 of a second. The other is lit with a flash in High Speed Sync mode at 1/2000 of a second. Can you tell which is which?

So, there you have it. High Speed Sync is not helping you freeze motion. It is mainly used for outdoor photos where you want fill flash at wide open apertures for limited depth of field and/or to control the ambient exposure. For example, let's say your are making a portrait outdoors and you want to use an aperture of f/2.8 and on that particular day the shutter speed would need to be 1/2000. Without HSS or the use of neutral density filters you can't use your flash to fill in shadows. You would have to lower your shutter speed to 1/200 to sync, and that would need an aperture of f/9 (3-1/3 stops difference). Using HSS would allow you to photograph at 1/2000 @ f/2.8 and use your flash (in pretty close to the subject, as it won't be a very powerful flash). It will also allow you to go to 1/4000 @ f/2.8 to darken the ambient exposure while still giving the subject the correct flash exposure.

What about HSS in the studio. Is HSS valuable in a studio situation? That depends on the lights you are using. Personally, I can’t think of a reason to use HSS indoors with speed lights. In ETTL mode you can set the aperture you want and a low ISO to be able to take photos at wide open apertures. With more powerful studio flash units it will depend on how low you can set the power on the flashes. If you find yourself with your flash at minimum power and it is still giving you a smaller aperture than you want, then you can  go into HSS mode and set your shutter speed above 1/250 and this will lower the power of the flash. Again, this is to control exposure, not to stop motion.

I hope this helps clarify things a bit. And, by the way, in the last image, A is 1/2000th of a second, B is 1/60th of a second.


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John Cornicello

 

 

 

More shutter speed and speed lights

Speed lights

Thanks for all the feedback on yesterday's shutter speed post here and on social media. Some folks wondered about the action stopping capabilities of the speed light. I only have one speed light to test with, a Canon 430 EXii. So here are some more photos of the fan.

First, I will start out with this series of photos taken with no flash. Here only the shutter speed of the camera is affecting the amount of motion blur in the fan blades. Shutter speeds range from 1/8 second to 1/1000 second using window light.

No flash, just window light at the indicated shutter speeds

No flash, just window light at the indicated shutter speeds

The next series was taken with the flash on Manual power control and the camera shutter set to 1/15th second. The first image is without flash to show the ambient light at 1/15 second at f/8. The images then progress from 1/64 power to full power. The f/stop was adjusted for each frame to give the same exposure.

flash-15th-second

This next series is the same as the above, except that the shutter speed was increased to 1/125 second. I want you to notice that most of the images look exactly the same, despite the three step difference in shutter speed. Where you will see a difference is in the low powered shots where the aperture had to be opened up to compensate for the low power flash, causing more ambient light to be recorded at 1/15th than at 1/125th. But the edges of the blades are still about the same, despite the ghosting.

flash-125-second

Here are close-ups of the fan blades at 1/4 power on the flash. On the left is 1/15 second at f/11 and on the right is 1/125 second at f/11. The motion blur is the same. The flash duration is the effective shutter speed in the studio. The flash doesn't care how long the shutter is open, and the flash isn't affected by how long the shutter is open (as long as the shutter speed is at or below the sync speed). If the room was completely dark the camera shutter could be set to 30 seconds or more and the exposure would still be the same as at 1/125. The only light hitting the fan is the brief flash from the speed light.

15-vs-125.jpg

One more series of photo and then I hope we're done with the fan and can get back to more creative endeavors. This time the flash is in eTTL mode at a range of shutter speeds. The aperture is the same (f/5.6) in the 6 flash lit shots, the output of the speed light is controlled by the eTTL circuitry. The seventh image is the fan at 1/2000 second with no flash for comparison.

ettl-flash

One of the things to notice in this series is that at 1/15 and 1/125 (the first two images) the flash is in normal mode and the speed of the flash freezes the blades. Above 1/200 second the flash is in high-speed sync mode where the flash fires a series of flashes (too quick in succession for the eye to see) as the shutter curtains move across the sensor. Because of the rapid movement of the fan blades, they are in different positions for each of the flashes and the fan blades show more motion at the faster shutter speeds (1/250, 1/500, 1/1000 second). At 1/2000 second the shutter speed alone stops the blades, as you can see by comparing the last two images, both taken at 1/2000 second. One is with the and one is without the flash.

As pointed out by Paul in the comments on yesterday's post, most subjects probably won't be moving as fast as the fan is, so you might not get a lot of subject motion blur using high-speed sync. I am exaggerating the effect here to make the point that high-speed sync is a tool used to help balance outdoor exposures between flash and sunlight while maintaining large apertures for shallow depth of field. It isn't meant to help stop subject motion, and, as can be seen here, may actually show more motion in extreme conditions.

Comparing Light Modifiers

Comparing Light Modifiers

Click through to the full post comparing various photographic light modifiers and how they work with studio strobes and speed lights. Comparing 7' parabolic umbrellas, shoot-through umbrellas, soft boxes, and more. What is your go-to light modifier for portraits?

Read More

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

 

It Is More Than Just Size

More than just the size, it is what you put into it

A big rage the past couple of years has been a proliferation of low cost 7' "parabolic" umbrellas from various manufacturers. I'm not going to get into the arguments of who created the first one, or who stole who's design. My concern is more with how they are being used.

By now we should all know that the size of the light relative to the subject determines the quality of the light. Large lights give a softer, less-shadowed look. Smaller lights give a harder, more contrasty look. So, the immediate thought about a 7' umbrella would logically be that it is a very soft light. And it is. Or at least it can be. But it also to depend on what light source you use with the big umbrella.

I see a few kits offered with the 7' umbrella and a  bracket to use your speed light/lite with it. Speed lights are normally a small and hard light source. So, if you bounce it into a gigantic umbrella it should become a big and soft light. Makes sense, no? 

Maybe not!

Below is a set of images of such an umbrella with a speed light attached and bounced into the umbrella. The flash is a Canon 430EX II in manual mode. The three images across the top row were taken with this combo. In the first one, the flash was set to the 105mm zoom position. There is hardly filled any of the umbrella. Yes, the light will be larger and softer than direct flash. But probably not what you were expecting. So, for the second image the flash was zoomed out to the 24mm position. Uh-oh! That isn't all that much wider than the 105mm position when the umbrella is so close to the flash head. Additionally, we see that the flash bracket doesn't come close to pointing the flash into the center of the umbrella. What to do?

The third image was taken with the flash head's built in diffuser panel popped out and over the flash. It does a much better job of filling the umbrella, but I had to open up 3+ stops to get enough light into the umbrella. And it still doesn't quite fill the umbrella evenly, note how dark the bottom portion of the umbrella is.

I imagine that a bracket to hold 3 or 4 speed lights with the umbrella shaft centered around them would be a big help, but also a big expense. Unfortunately, I only have one speed light and a single bracket, so can't test that one out.

Just as a way of comparison, I took two more shots using a studio flash head, a Speedotron 202VF. The first of these images has the standard 7" umbrella reflector. Even with this combination, the umbrella isn't quite filled by light, but overall it is much more efficient. To get the umbrella to fill with light, for the last image I took the reflector off the strobe head. With the bare tube the umbrella is finally filled. It is not quite as bright. And you need to be a lot more careful if using the umbrella rig off to the side that direct light from the bare tube doesn't hit your subject causing very distracting shadows.

parabolic-speedlight.jpg

Take from this what you may. I just wanted to make sure you understand that just having a super large light modifier doesn't mean that you have a super large light source. I encourage you to do a similar test with your own lighting equipment to see what it is really doing.

Thanks!
John

PS: I also tested out a silver 7' parabolic. You can see those results in this post.

PPS: I then pulled out all the modifiers I could find around the studio and compared them all in action in a new post.