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Archive 2013 · Canon flashes
  
 
Gochugogi
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p.2 #1 · p.2 #1 · Canon flashes


jerrykur wrote:
My suggestion would be to put the flash in manual and live with that for a while. The Strobist blog is a great help.
Also check out Chuck Gardner's posts when you want to go with ETTL. Chuck knows more than almost anyone about how to managed Canon ETTL to get what you want.



The 420EX only does E-TTL auto mode (& TTL on old film EOS). No manual mode unless you short the contacts and have it fire full power only! However, you can control FEC from most any EOS DSLR and use it as an E-TTL slave with a master unit. The 420EX is not compatible with flash menus controls of newer cameras. As I recall, the 420EX worked with the flash menu of my 10D/5D but not with my 5D2 or 7D.



Jan 31, 2013 at 10:26 PM
mikegrados
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p.2 #2 · p.2 #2 · Canon flashes


Cactus V5, Lumopro 160 (or equivalent), and your wallet will thank me. Using Canon speedlites is good for ETTL/Auto/on-camera. If you're going to put a flash off your camera, all you need is something simple to manually set up.

I see you were into'd to strobist. Great! Read it, experiment, read it again, and keep progressing. Start w/ one flash - you can do a lot with only one light and a modifier.



Feb 01, 2013 at 01:33 AM
cgardner
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p.2 #3 · p.2 #3 · Canon flashes


Someone mentioned my Canon tutorials. They are at http://photo.nova.org if you haven't found them already.

I started with flash a long time ago shooting weddings with one over the camera with a bracket and another off camera. If you've not done lighting with flash it may not be obvious that the "big picture" goal technically is to match what's in the flashes reach to the sensor range EXACTLY and why that configuration is ideal for that task.

If you started in a dark room with manual flash you'd:
1) Set camera f/stop for DOF
2) Add fill power until you see detail in the shadows
3) Then add OCF over fill until highlights are just under clipping.

Do those three steps and you get detail everywhere. You change scene range with fill and key to match the sensor range.

With one flash outdoors you need to shoot into the shadows. Don't fight the sun with flash, you'll lose. Take the sun out of play by keeping it off the front of the subject, expose for the sun, then add flash to the front to match. It can be done with one flash IF you don't create a lot of shadows on the front with the flash.

Here's a typical "worst case" single flash situation. Bride and groom in backlight of the sun. Extreme black <> white tonal range and you MUST have detail in both.

1) Set camera manually to "Sunny 16" to expose the sunny parts of dress on back/sides. Faces / front of dress 3 stops underexposed because skylight is Shady 5.6.

2) Get faces up into the skylight. If eyes are shaded before adding flash they will still be darker after adding it because flash hits cheeks and eyes equally. What you are doing here is posing faces to brightest part of sky so it's centered on nose casting shadow down. Nice flattering modeling but just too dark at "Sunny 16" needed to hold highlight detail on dress in sun.

At this point of you add flash from on camera at eye level it will cancel that natural modeling and look like any flash on camera shot: unnaturally 2D. 3D modeling is controlled by ANGLE OF LIGHT TO FACE and flash is too low. That's why you need a bracket or some other means to raise the flash used near the lens up above the face.

With bracket mimicking the natural downward modeling already in the face it's not fill it is a second "key" light. That defies conventional wisdom but in terms of cause and effect if a flash creates 3D shadow clues it's role is "key" not fill. Here the fill comes from the skylight hitting from all directions.

3) Raise power of flash until the front side of white dress is slightly darker than the sunny parts (which still have detail). That can be done in ETTL mode by letting the camera take a guess at FEC =0 then correcting FEC or starting with the M power that normally works at the 8ft shooting distance and adjust power. It's the same dial on the flash for both. Both are as simple.

Here's what it looks like:





Skylight models front side first (because subject looks up to get light in eyes). Set ambient on white jacket 1-click 1/3 stop below the clipping warning in M mode. Add flash power until front side is triggering clipping warning, then back off 2-clicks (2/3 stop) putting front side of white jacket 1/3 stop below back.

The lighting isn't flat / 2D because flash comes from natural downward angle. There's detail almost everywhere because flash hits just about everything the camera sees as "key" light and the few shadows "filled" by the skylight are not noticed much.

You can get those with any one EX flash if you raise the flash off camera. What a 580ex, 580exII or 600ex-RT will allow is greater range. You don't need fill because raising the flash on the bracket hides all those nasty dark unflattering shadows on the nose you see in the hot shoe.

When a flash is moved off axis it creates shadows. Those shadows will need fill from some other direction. It can come from a second flash, ambient, and by the "spill fill" off the walls indoors:












That's a dual flash scenario I've used forever. Placing the OCF 45 degrees from the nose and 45 degrees above the eye line creates very natural looking flattering modeling. The camera angle there is oblique, but walk around to profile and it's beautifully lit and the same is true full face. Unlike daylight where the face is moved to the light here I walked the light around until I saw the face obliquely. What is seen from behind the stand is what winds up highlighted on the face. Really no brainer simple if you look at it that way; your eyes are the "modeling lights".

What makes the shadows light/dark and seem soft/light in the key-over-fill scenario is the amount of fill. In ETTL ratio mode you just dial it in. I didn't use Canon flash for those shots but its how A:B=1:2 looks. That's A Master fill on the bracket and B off camera. Exposure is as simple as one flash, just adjust FEC on the dial of master (more convenient for me than camera) until the highlights are just under clipping in the playback. Same position strategy below but with 1:1 ratio (Fill = Master).







The thing to understand here about the gear is that when using two flashes for key and fill you'll want them both to be the same power for a shot like above with light open shadows and the slave 2x brighter for the darker "normal" room light look in the other shot.

As while your 7D can fire a slave and provide enough fill in many situations it's low power will be limiting in others. There's another reason having a 580ex Master flash on the bracket is good idea...












When the subject isn't holding a pose so I can PRECISELY place my OCF on the face for a flattering pattern I roll it behind and use it as "rim" lighting to create the illusion of 3D space and light the space more evenly. That means the flash in front must be powerful and RAISED to make the angle flattering. That's why I bought a pair of 580ex and keep one on the bracket and the other on the stand and use variations on those two scenarios for about 90% of my flash shots.

If in your place with an old 420EX I'd keep it a slave flash for ETTL shooting and buy:

600EX-RT (best long term investment)
Stroboframe Camera flip bracket with quick release (under $50 and does the job)
Canon or third party TTL cord (2 foot)

That will allow you to handle outdoors scenarios as shown above and just about any indoor scenario with one flash with flattering lighting on people.

The 600EX-RT as master is backward compatible with the 420EX optically so you can use the 420EX as slave that way but long term when budget allows replace it with a second 600EX-RT and you'll will have greater range and more reliable signaling.

At that point you will not be able to use the 420EX (unless keeping the 600's in optical mode) but by then you probably won't want to use it.

There lots of other great ways to use flash, but I can only recommend personally what has worked quite well for me. Getting the bracket solved the direction problem critical to natural looking flash lighting without needing to drag a stand around. With dual flash there's only one to drag around.






Feb 01, 2013 at 03:47 AM
Gyroscope
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p.2 #4 · p.2 #4 · Canon flashes


Thanks for the great post cgardner!


Feb 01, 2013 at 07:46 AM
Michael White
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p.2 #5 · p.2 #5 · Canon flashes


With so many likening the 550 now I know why I can't find them for sale they work great with the pocket wizard mini and flex no rf interference the only master iirc.


Feb 01, 2013 at 12:24 PM
Mike Bons
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p.2 #6 · p.2 #6 · Canon flashes


I use the 7D built in flash often to control multiple off camera flashes which works great for my needs. However one caveat to this setup is that the built in flash is not capable of high speed synch, so you will be limited to a max synch speed of 1/250 which may or may not matter to you.

Mike



Feb 01, 2013 at 01:58 PM
cgardner
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p.2 #7 · p.2 #7 · Canon flashes


Mike Bons wrote:
I use the 7D built in flash often to control multiple off camera flashes which works great for my needs. However one caveat to this setup is that the built in flash is not capable of high speed synch, so you will be limited to a max synch speed of 1/250 which may or may not matter to you.

Mike


HHS is the main reason I dumped my trusty Vivitars for the Canon 580ex. Before abandoning film SLRs entirely I shot with a Minolta D7Hi with an EVF and no sync limit. I got very spoiled shooting outdoors at any shutter speed.












When I got my 20D and used the Vivitars it was no different indoors but outdoors shooting at f/11 @ 1/250th was like someone slapping on creative handcuffs.

Yes the practical range is limited in HHS mode with even direct flash to 7ft with one and 10ft with two (I know because I tested range at full 1/1 power) but that range works for most people shots outdoors in direct sun and the ability to blur the distracting background makes a huge difference in the visual impact of the foreground subject.











Direct flash also works for people in that backlight strategy if you first pose the face up to the skylight, center the fill on bracket and place the "key" slave flash as the same angle as the sky key vector as explained previously. Below is not the best example... I pulled the in-house model out of the garden to take it in the middle of a discussion on outdoor modifier size. It was taken with direct flash on bracket for fill with slave to the right and above. Note the smooth transitions on the front of the face. That's the diffuse skylight doing most of the work. Also note the absence of a "nuclear" halo around the hair. That's the result of starting with all highlights the ambient sun hits below clipping with shutter speed / aperture.









Feb 01, 2013 at 03:07 PM
BrianO
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p.2 #8 · p.2 #8 · Canon flashes


cgardner wrote:
...the practical range is limited in HHS mode with even direct flash to 7ft with one and 10ft with two...


That would depend on the aperture and the ISO setting.



Feb 01, 2013 at 08:21 PM
cgardner
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p.2 #9 · p.2 #9 · Canon flashes


BrianO wrote:
That would depend on the aperture and the ISO setting.


In HSS mode camera sees the pulsing flash as a continuous source (similar to fluorescent). That's why the change in aperture from 5.6 @ 1/500th to 2.8 @ 1/2000th at 10ft didn't change the net exposure as a change in aperture with single pulse regular flash would. A 2.0 lens would require 1/4000th wide open and 1.4 lens would max. out shutter at 1/8000 on my camera but the net exposure for ambient and flash wouldn't change. Lucky I don't own the 50mm f/1 because I'd run out of shutter and blow the sunny highlights at ISO 100. I'd also need to move the flash back or reduce power with f/1 lens for same reason. Send me one and I'll tell you what distance

Changing ISO to 200 @ 2.8 would require changing shutter to 1/4000th to compensate and avoid the sun clipping the highlights it hits. ISO 400 would max. out the shutter on my camera at 1/8000.

But since the camera is also seeing the light of the flash as continuous and the net exposure remains the same because shutter compensates for the ISO increase any increase in flash distance at the 1/1 max. power setting would seem to result in an overexposed foreground. The sun has set here so I can't confirm with actual test at the moment.

Granted the limiting factor here is the decision to keeping the sunny highlights under clipping because my goal is recording a full range of detail with no blown highlights. Your goals and flash range may vary from mine but it would seem the foreground would become underexposed if distance of flash were increased in that test if sunny parts were kept below clipping.

FWIW - using HHS in ETTL mode can get confusing because you never know when the flash is outputting at full capacity and additional + FEC will not compensate for changes in distance. That confused me at first until I did HSS tests in M mode at 1/1 power and found the max. range by walking backwards until clipping disappeared on flash lit objects.

Since ambient skylight is under the flash on the shaded side that's also a variable. On sidewalk or a beach with sun blasting fill up into the shadows off the ground the range would be greater.




Feb 01, 2013 at 11:25 PM
BrianO
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p.2 #10 · p.2 #10 · Canon flashes


cgardner wrote:
...the practical range is limited in HHS mode with even direct flash to 7ft with one and 10ft with two...


BrianO wrote:
That would depend on the aperture and the ISO setting.


cgardner wrote:
In HSS mode camera sees the pulsing flash as a continuous source (similar to fluorescent). That's why the change in aperture from 5.6 @ 1/500th to 2.8 @ 1/2000th at 10ft didn't change the net exposure... A 2.0 lens would require 1/4000th wide open and 1.4 lens would max. out shutter at 1/8000 on my camera but the net exposure for ambient and flash wouldn't change.


So many assumptions here. You're giving equivalent exposures, so of course there wouldn't be a change, but not everyone would be using those equivalents.

Lest anyone be confused by Chuck's statement, he's seemingly operating under the assumption that everyone reading this would be facing the same ambient exposure. If he had said "the practical range is limited to 7 feet when using HSS under full noonday sun in the mid latitudes..." I might not have posted, but since he didn't I feel it important to again state that the range of a Speedlite in High Speed Sync mode will vary depending on the aperture and the ISO setting, and those parameters are dependent on the intensity of the ambient light and the ambient-to-flash balance one is trying to acheive.



Feb 02, 2013 at 04:07 AM
 

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BrianO
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p.2 #11 · p.2 #11 · Canon flashes


BrianO wrote:
...Canon's optical wireless system can handle three "Groups" of flashes. The Master -- whether a built-in flash or a hot-shoe/cable-mounted Speedlite -- is always Group A, and Slave flashes can be assigned to Group A, Group B, or Group C.


I stand corrected. I was out playing with my 7D today and discovered that the Flash Control Menu had seperate settings for flash power for A, B, C, and pop-up flashes. I had always been under the impression that the Master was always Group A, but that seems to be the case only when the Master is an attached Speedlite.

Using the pop-up as a fourth "group" has some interesting possibilities, especially if used with a deflector like the Lightscoop.

http://www.lightscoop.com/

I'll be playing with this feature over the next few weeks for sure.



Feb 02, 2013 at 04:41 AM
cgardner
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p.2 #12 · p.2 #12 · Canon flashes


BrianO wrote:
Lest anyone be confused by Chuck's statement, he's seemingly operating under the assumption that everyone reading this would be facing the same ambient exposure. If he had said "the practical range is limited to 7 feet when using HSS under full noonday sun in the mid latitudes..." I might not have posted, but since he didn't I feel it important to again state that the range of a Speedlite in High Speed Sync mode will vary depending on the aperture and the ISO setting, and those parameters are dependent on the intensity of the ambient light and the ambient-to-flash balance
...Show more

I'm quite good at putting words in my own mouth... and the example used was noon day sun. Brian's original statement that Aperture and ISO change flash distance is not correct in that context or for any ambient level. On a overcast day? Yes the range would be greater, but then changing Aperture or ISO wouldn't affect that range as it didn't on a sunny day.

What changes the flash range outdoors is the INTENSITY of the ambient light the flash must try to match when the ambient highlights are kept under clipping with ISO/Aperture/Shutter. That's greater on a sunny day than an overcast day, or if shooting on sunny day in open shade where there is not direct sun hitting the subject or background one needed to avoid blowing out in the highlights. There's also no rule saying that highlights can't be blown out either. Blowing highlight mean the shaded parts also get lighter and less flash power is needed for correct exposure on the shaded side / greater max. range.

But again, practically speaking, in open shade or overcast days I usually don't even use HHS because I can keep the shutter at or below the 1/250 sync limit and get the aperture desired and reap the benefit of the greater power in regular flash mode which makes the use of modifiers (which cut output by 1-2 stops) possible.

My first exoposure "meter" starting in photography in the late 60's was not electronic, it was the little chart inside the yellow Kodak box with icons of a person standing in sun and shade.

While BrianO loves splitting hairs about how lattitude and sun angle it afffect might affect ambient exposure and flash range in the shadow Kodak seemed to think "Sunny 16" and "Shady 5.6" predicted results in those two situations close enough, practically speaking.

Practically speaking means that IN SUNLIGHT I could set my camera to 1/100th @ f/16 with ISO 100 film and be assured faces in sunlight would be correctly exposed when I got my prints back from the lab. When I moved into the shadows the chart and remembering "Shady 5.6" reminded me to adjust on or more of the exposure variables. I could change aperture from f/16 to f/5.6, a three stop difference, or lengthen the shutter time to 1/25th second to arrive at the same "Shady 5.6".

Last time I checked the sun was still working pretty much the same as it was in 1968, which is why I get the same predictable results and still use the same "Sunny 16" / "Shady 5.6" rule of thumb. What has changed since the days of film in that paradigm is the ability to change ISO at will and to see the results of the exposure immediately.

As in 1968 don't use a camera meter outdoors in a situation like that test shot because I know the sunny side will be "Sunny 16". So I set the camera to the Sunny 16 equivalent, take a test shot and look at the results WITH THE CLIPPING WARNING ON. If I see clipping in highlights I adjust whichever variable I'm not using at the "creative constant".

"Creative Constant" may be a term you are not familar with. No surprise there because I just made it up. I really annoy Brian when I invent new terms. ... so let me define it:

There are three exposure variables: ISO, aperture, shutter. When the primary goal is shallow DOF to create visual separation APERTURE becomes the "creative constant" the other variables are adjusted around. When the primary goal is either freezing motion or a creative blur effect of subject or background (with panning) the creative constant is the shutter speed and aperture / ISO are adjusted as needed for the desired exposure, which for me is detail on the solid white non-specular highlights, with few exceptions.

ISO is almost never a creative constant. It is usually the thing that is adjusted last in a creative situation after making the decisions on DOF and stopping motion to arrive at the technically correct "Sunny 16" or "Shady 5.6" exposure. I qualified that with "almost" because a varible that results from ISO speed is amplification noise in an image.

For example in Av mode at ISO 100 indoors in a dark room the shutter will "drag" forever until there's enough light captured in the white highlights. At ISO 3200 the metering closes the shutter faster because it knows the A/D converter will amplify the smaller number of photons it managed to capture in the highlights while the shutter was open a shorter time. There is more noise in the shadows because more dark values in the scene fall below were the sensor site records a signal over the residual noise.

The sensor sites are "dumped" of charge like water in a bucket and the noise is what's left over from the last exposure. Part of the A/D process when noise reductions is used is to to subtract a "black frame" map of just the noise (i.e. like a long exposure with the lens cap on) from the scene image. But in high ISO shots so much image content hovers around the noise threshold it can cause a loss of shadow detail vs. a shot where there is adequate light in the shadows. That's why regardless of ISO used it's better to err on the side of overfilling shadows with flash at capture. They might be recorded incorrectly perceptually and technically as gray SOOC instead of black but the higher S/N ratio will make them less noisy when darkened back to their normal black value in PP.

The appearance of the results change in the photo because at ISO 3200 the camera's analog/digital converter amplifies the signal more. That amplification affects what is called the "Signal/Noise" ratio. Without getting too technical it's like the drops of water that cling to the sides and bottom of the bucket when it is dumped. If there are 18 milion buckets the amount of water remaining will vary. On the sensor it residual voltages in the "empty buckets" (shadows areas not recording a signal) which create that random rainbow pattern of "noise" the shadows.

High ISO "noise" is similar in appearance to the courser grain structure of high ISO film emulsions and it the goal is to create the look of ISO 400 Tri-X or Kodachrome shot above its rated speed and "push" processed then a digital photographer might set the ISO higher than 100 outdoors in sunlight first as the creative variable, then adjust aperture narrower and shutter duration shorter to get to the "Sunny 16" technically nominal expoure.

My Decision Tree

In a backlit sunny portrait situation my first creative constant decision is aperture to control DOF. I rarely shoot action like race cars or airshows so my secondary creative constant decision about shutter is just whether or not it will be fast enough to prevent blur.

The DOF decision is affected by my choice of flash mode and shutter sync limit. When I need maximum range for the flash in the foreground I will temper my desire for insanely great Bokeh (why I bought those expensive 2.8 L lenses) for the sake of flash range and start the exposure process by setting shutter to 1/250th, ISO to 100, and aperture to f/11 to take the first shot. That's "Sunny 16" adjusted for the change in shutter.

You'll notice that "Sunny 16" should actually be 1/200th @ f/11 at ISO100. But what I discovered by exposing per the clipping warning is that the ISO indicator on the camera isn't accuracte. The actual speed of the sensor is about 1/3 stop faster. So 1/250th while not "theoretically" correct is in fact the shutter speed needed to retain detail on the sunny highlights. Any variation in lattitude, etc. is taken into account by adjusting from that starting baseline when I look at the first shot's clipping warning and right side of the histogram. I want to see no blacked out areas and no big flat gap on the right side of the histogram (an indication of underexposure).

I just didn't fall off the back of the truck holding a camera and as I mentioned in the follow up environmental variables will affect both the amout of light and the color temp of the shadow side. "Average" conditions are the "Shady 5.6" baseline Kodak recommends. Shadows will be lighter if more sun than average is bounced into the shaded side buy the ground, white wall, brick wall (which will also ad a nasty red cast), etc.

That's exactly why in most situations I put my flash in ETTL mode at FEC=0 and take a test shot. I didn't in that test because I was testing full power range. But here's a test I did earlier with Av / ETTL mode with the objective of seeing how well the metering "guessed" at EC=0 for Av and FEC=0 for ETTL:

The test was done at 11AM at 34 north lattitude. I started with a baseline shot faceing west using only ambient lighting, setting exposure as described from the Sunny 16 baseline with adjustment per the clipping warning on the white towel:







The caption says "Flat Light" but that's not correct it's directional but most of the content in the foreground is "key" lit by the sun over my left shoulder as I took it. The "fill" controlling how dark the shadows on the gray card the towel casts is coming from the "Shady 5.6" skylight. Not many areas without detail because the sensor (a 20D) as a range long enough to cover a scene which is mosting in the "key" light.

Here is the same light conditions seen facing East:





EC=0 in Av mode blew out the white towel because the cameras evaluative metering was trying to make the center of the frame look "normal". Above I dialed in - 2 EC to get the white towel under clipping.

Next, I reached up and turned on the flash over the camera on my bracket in ETTL mode at FEC=0 and got this result:





This shows the histogram on just the card in the foreground which has a full tonal range:






The histogram indicates near perfect exposure and in the RAW SOOC neither the sunny or flash lit parts of the white towel are clipping. Perceptually it looks a bit overexposed, in part because the flash overpowered and canceled the modeling of the skylight seen (but underexposed) in the ambient only shot. That's the cause and effect I mentioned earlier and why I use two flashes outdoors.

If using two for that shot I'd put the slave at the same angle as the skylight's "key" modeling vector, set the A:B ratio to 1:2 and take a shot at FEC=0 and get similar results. That's exactly what I did in the dual flash test shot of the in-house model in the dual flash obilque pose:







Being a technician and technical manager in printing for a living made me very process control oriented. When testing I make one factor constant, such exposure of highlights under clipping. Which allows me to see the effect of the other variables.

In the first ambient shots facing West and East the fact I exposed for highlight detail (not what the meter said was correct at EC=0) allowed me to see how my 20D sensor range handed the contrast of "flat" (mostly highlghted) and backlit (mostly shaded) scenes.

Once I dailed in the "Sunny 16" expsoure with - 2 EC in Av mode to keep detail in the highlights of the backlit scene that became the constant for comparing how well the flash metering determined how much power to output in HSS mode to nominally expose the card in the center of the test shot and similar toned face of the in-house model.

What that test showed me is that if you first EXPOSE HIGHLIGHTS IN AMBIENT BELOW CLIPPING PER THE WARNING, the flash metering at FEC=0 nails the exposure on the front side nearly perfectly. It's damn near a perfect match to the sunny side technically (same eye dropper reading in the RAW) with just a slightly higher reading on the sunny parts. But to be PERCEPTUALLY normal I would expect the shadows to look darker that the sunny parts and if the goal was the match the chart more normal (not test ETTL flash metering in HHS mode) I would have dialed it -1/3 to -2/3 FEC to cut back the flash a bit.

If using manual flash in that situation?

I'd start at 1/2 power, take a shot, look at the results...
if under exposed in front change flash to 1/1
If over exposed and clipping change to 1/4
Take second test shot
-- adjust as above
Take third shot and evaluate... I will usually be perfect

In computer programing parlance that's called a binary search. Starting in the middle reduces the steps needed to find the target value.

That's how I roll whenever using M flash mode. Even when using ETTL ratios I have the flash pre-set so A and B flashes are set to 1/1 power. Why 1/1 instead of 1/2 in the example above?

As mentioned previously in ETTL mode you really never know what % of power was used in the last shot. For example I might be shooting at FEC=0 from 15ft. with HHS and the results are underexposed. I dial in FEC= 1 but nothing happens. Why? Because at FEC=0 the flashes were already firing at or near 100% capacity.

When that happens I press the mode button from ETTL to M and fire off a quick test shot at 1/1 on both fill and key. Looking at the results of that full power shot tells me which flash is out of range at 100% power.

For the OP, that's something you might want to do if using a 580ex Master and 430ex slave which is weaker. It can't be done with a 580ex / 420ex combo because the 420ex is ETTL only can can't be switched to M mode from the Master.

I did the HSS range test at 1/1 to find the range limit. Now I know that if shooting much beyond 8 ft. I shouldn't use HSS. I'll switch to M mode at that point, set shutter to 1/250th then adjust aperture for correct highlight exposure in the ambient lit highlights then in the shadows adjust flash power manually or in ETTL with FEC until it "looks right" for the context of what I'm shooting and how I want to depict it creatively.

WIth single flash I usually use M for flash adjustments if shooting in one spot to eliminate the frame-to-frame metering variable. I'll do the same with dual flash in static situations controlling the ratio and scene-sensor match on what the flash hits with the relative distance of the fill and key set at the same power.

Some might not have grasped that in the two flash 1/1 test the fact the "key" is at 6ft vs the "fill" at 10ft is what is controlling the lighting ratio on the flash lit target.

In the test I moved my camera position with fill over the camera until I saw shadow detail in the playback. I wasn't going for an exact eyedropper reading on the black patch of the color chart because I had no way to measure that. I just looked for detail on black objects like the border of the chart and tape holding it and the black A clamps and stant locks. Then I moved the key light in until the highlights it created over the skylight and flash fill were below clipping. That's why it wound up at 6ft, not 7 or 5.

It is because there are so many variables involved I have come to make all my critical exposure and tonal range / ratio decisions with my eyes and brain based on the technical and creative goals for each shot using the new methods digital allows for process control:

Playback of the results (visual evaluation of detail on white / black objects, scene and test targets)

Clipping warning (highlight exposure decisions)

Histogram:

Right side gap = underexposure
Left side running off = scene exceeds sensor range (when highlights exposed nominally)
Left side gap = scene shorter than sensor range (e.g. overcast / foggy conditions / open shade)

Middle part of histogram: overall distribution tells me if scene is lighter/darker than average. Not really a factor in my exposure decisions.

I always expose for highlight detail and use flash for full range in foreground when possible. When not possible I compose shots with sun behind me so all important content fits sensor as in the "facing West" test shot at 11AM.

Because of my situational awareness of light if shooting a soccer game I will stand on the side of the field where sun is over my shoulder for the action shots so black and white uniforms fit the range of sensor better, but for a close up of a player put sun to their back and use dual flash in front to record a full range of detail:







Flash configuration for shot above:










Edited on Feb 03, 2013 at 01:00 PM · View previous versions



Feb 02, 2013 at 12:52 PM
BrianO
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p.2 #13 · p.2 #13 · Canon flashes


cgardner wrote:
...While BrianO loves splitting hairs about how lattitude and sun angle it afffect might affect ambient exposure and flash range in the shadow Kodak seemed to think "Sunny 16" and "Shady 5.6" predicted results in those two situations close enough, practically speaking.


Right! In those two situations! In other situations one would need to extrapolate to determine the correct exposure.

But you didn't do that; you flat out said there was only one maximum range for a 580EX in High Speed Sync: "7 feet." This isn't a matter of "splitting hairs." It's fundamentally wrong; one size doesn't fit all. You can try to cover yourself by posting another of your long-winded and barely relevant posts, but it doesn't change the facts.



Feb 02, 2013 at 03:11 PM
cgardner
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p.2 #14 · p.2 #14 · Canon flashes


There is only one max range at full power for any flash determined by its guide number. GN varies on a zooming flash head but below I use 50mm which is in the middle of the range and what I used for my test.

At ISO100 @ 1/250 @ f/11 (for correctly exposed ambient highlights) @ 50mm flash zoom range of 580ex at 1/1 shows 15 ft as distance for correct exposure per the indicator on the back of flash which I've found to be accurate in M mode.

Changing to 1/500 @ f/8 @ ISO 100 is the same net ambient exposure but flash shifts into HSS automatically and range drops to 7 ft. as expected because HHS uses more current for the same net exposure vs. single burst mode. If shooting with flash you'd need to move from 15ft to 7ft when HSS kicked in to avoid underexposure.

Change settings 1/1000th @ f/5.6 @ ISO100? Same net ambient exposure. Same 7ft indicated HSS range.

Now change ISO to 200:

Shutter / Aperture (net) must also change - 1 stop to avoid ambient over exposure

1/1000 @ f/8 @ ISO 200 Same indicated 7ft HHS range
or
1/2000 @ 5.6 @ ISO 200 Same indicated 7ft HHS range

Increase ISO? Same compensation is needed to keep ambient exposure the same.
1/4000 @ 5.6 @ ISO 400 Same indicated 7ft HHS range
1/8000 @ 5.6 @ ISO 800 Same indicated 7ft HHS range

Again the behavior in HSS mode differs from single burst because the camera sees the pulsing flash as a continuous source. That's why HHS works with the narrow moving shutter curtain slit at indicated speeds above 1/250th on my crop body. The actual curtains move the same speed at all indicated settings. What changes is the latency between the curtains and distance between them as one chases the other across the narrow dimension of the frame.

Distance is always 7ft in HHS with single flash in M mode at 1/1 here because overall exposure controlled by ISO/Aperture/Shutter is predicated on exposing the sunlit parts below clipping. My outdoor test was just a confirmation of what the distance indicator on the back of the flash indicates.

If one chooses to intentionally blow highlights allow the ambient light to render the shaded content lighter that changes the "target" exposure the flash must match. For example if you blow highlights by one stop:

1/1000th @ f/5.6 @ ISO100 Highlights under clipping
to
1/500th @ f/5.6 @ ISO 100 Highlights blown by 1 stop

The indicated HHS range will change to 10 ft. If you took the shot at 7ft the background and flash lit foreground would both be blown by 1 stop. If you move back to 10ft with the flash the background will still be blown out but the front will be correctly exposed.

The more you blow the sunny parts the lighter you make the shady side too and less flash power is needed at the same distance or the further you need to move back to get correct flash exposure at the same power setting.

If you take a camera and put it in your lap with 580ex flash on it in HSS mode @ 50mm zoom you will duplicate all the readings shown above because that's what I just did to verify them.








Feb 02, 2013 at 04:50 PM
BrianO
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p.2 #15 · p.2 #15 · Canon flashes


You're repeating yourself, Chuck. Once again, you're using equivalent exposures (same EV), and assuming the same ambient contribution, so of course the range doesn't change. That's my point: your blanket statement only applies to that one exposure value. High Speed Sync is useful in more situations than that.


Feb 02, 2013 at 05:02 PM
cgardner
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p.2 #16 · p.2 #16 · Canon flashes


No it applies to the goal of capturing a full tonal range without any blown highlights. If that is the goal the strength of the sun is the limiting "creative variable" limiting the effective range of the flash.

Stop getting your knickers in a twist and about the fear that someone else might misunderstand what I wrote about the goal of the exercise using flash outdoors - fitting scene range to sensor. That means recording normal looking detail in highlights and shadows, not blowing the ambient highlights to change the max. range of the flash. That's not the goal.

You just can't accept my statement within the context of the exercise and my goals and want to apply it to some broader context outside of scope of the exercise and the stated goal. Many statements taken out of context will appear incorrect. If you have different goals the same facts may not apply and be true. Not because they are not correct but because it's a different situation / goals.

We all have different goals Brain but they don't affect the cause and effect of gear used to meet them. Let's agree to disagree on goals and move on...




Edited on Feb 02, 2013 at 05:36 PM · View previous versions



Feb 02, 2013 at 05:28 PM
BrianO
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p.2 #17 · p.2 #17 · Canon flashes


cgardner wrote:
If you take a camera and put it in your lap with 580ex flash on it in HSS mode @ 50mm zoom you will duplicate all the readings shown above because that's what I just did to verify them.


I just did better than that; I stuck my camera out my van's window and took an actual picture:

ISO 320, f/4.0, 1/800, ETTL II, HSS, 70mm (I have my 70-200 mounted). The range bar on my 580EX II reads 1 to 6 meters. That's 3.3 to 19.6 feet.

I didn't have a great subject on hand, so I just did a brick wall test, but it's not "blown" at ISO 320 and f/4.

SOOC except for resize:








Feb 02, 2013 at 05:32 PM
BrianO
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p.2 #18 · p.2 #18 · Canon flashes


Just to be complete, I just switched to my 50mm lens, and still at ISO 320 and 1/800, but now at f/1.4, my range bar says 3 to 18 meters (9.8 to 59 feet ). Still not blown; still good tonal range.


Feb 02, 2013 at 05:40 PM
cgardner
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p.2 #19 · p.2 #19 · Canon flashes


Sure if you change all the variables and use ETTL instead if M at 1/1 you will get different readings. Duplicate my steps in 1/1 M power at 50mm zoom and you'll get identical result.

Plus how often do you actually see the sun there? Perhaps that's the problem, you don't recognize what Sunny 16 looks like

If overall ambient isn't Sunny 16 the bar the flash must match is lower and the max. range greater. We don't disagree about how the gear works, only the creative goal and criteria for successfully meeting them.

Show me some actual results on a sunny day with a scene identical to my test and then we can continue the debate. Until you are willing / able to do that give it a rest.

I'm checking out here...


Edited on Feb 02, 2013 at 05:49 PM · View previous versions



Feb 02, 2013 at 05:41 PM
BrianO
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p.2 #20 · p.2 #20 · Canon flashes


cgardner wrote:
...how often do you actually see the sun there? Perhaps that's the problem, you don't recognize what Sunny 16 looks like


Exactly; as I said before: we aren't all shooting under bright mid-day sun, so your one-size-fits-all statement that 7 feet is the maximum range in HSS isn't true...as I have just proven.

cgardner wrote:
...we don't disagree about how the gear works, only the creative goal and criteria for successfully meeting them.


You've got that right.



Feb 02, 2013 at 05:48 PM
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