Blowing out the sun

bibowj · Aug 9, 2009

One of my favorite effects is when someone shoots a client in normal daylight, and by using high powered strobes the sky is darkened. Ive seen this used by some of my fav photogs but they generally shoot digi (with cameras that sync above 1/250).
My question is, if I doing this in traditional film (MF) on a 'blad with strobes, how would I meter it to get the correct exposure since I cant chip it? I shoot canon in digi and my 5d only syncs to 1/200. I imagine I could Polaroid it, assuming I have that back (which I dont) but im sure theres a basic equation out there that would work usin ambient and fill etc...

Please enlightenment if you happen to know..

(if youre wondering the exact effect Im meaning, look at Dead Link Removed pretty much any of his outdoors stuff is done that way...

Ian Tindale · Aug 9, 2009

This effect is known as "synchro-sun".

eddym · Aug 9, 2009

Whatever the ambient light is, you just overpower it with your strobe. For example, if it's an f16@1/125 day, then light with the flash for f/16 and set your shutter for 1/250 or 1/500 to underexpose the background. It's the opposite of fill flash, where you want 1-2 stops less flash than ambient. You need a strong flash.
Personally, I think the effect sucks, but whatever blows up your skirt.

2F/2F · Aug 9, 2009

It is no different with film than it is with digital. (Why would it be? Light is light.) You are effectively making two exposures in one shot; one using ambient light, and the other using flash. You need to meter for each to get what you want. When your flash meter and your ambient meter read the same exposure, you are at a 1:1 ambient-to-flash ratio. What you are doing by making the background a little bit darker is changing this 1:1 ratio to something like 1:1.5 or 1:2.

One method: Meter the ambient light first, and then set your camera to underexpose it by the desired amount. You then adjust your flash power until your flash meter tells you to use the f stop at which you are already set for the ambient exposure.

Another method: Meter the flash first, and set your camera's aperture according to the meter. Then meter the ambient light. See what shutter speed is recommended for the aperture at which your camera is set. Set the shutter speed to be faster that this, to darken the ambient light the desired amount.

The first method gives finer control, and also makes the desired exposure much more attainable with focal plane shutter cameras. This is because as the first step, a fixed shutter speed is set; one that will synchronize with electronic flash. Then, an f stop is chosen to match. Then, flash power is finely tailored to fit the f stop.

The second method is faster, but gives more course control (unless shooting with a camera that can set in 1/3 shutter speeds), and works best with leaf shutter cameras. This is because with a leaf shutter, you have the entire range of available shutter speeds to use for controlling ambient exposure. The ability to use shutter speed to control ambient exposure will never be nixed above a certain shutter speed, like it is with a focal plane shutter.

DanielStone · Aug 9, 2009

2F/2F said:
It is no different with film than it is with digital. (Why would it be? Light is light.) You are effectively making two exposures in one shot; one using ambient light, and the other using flash. You need to meter for each to get what you want. When your flash meter and your ambient meter read the same exposure, you are at a 1:1 ambient-to-flash ratio. What you are doing by making the background a little bit darker is changing this 1:1 ratio to something like 1:1.5 or 1:2.

One method: Meter the ambient light first, and then set your camera to underexpose it by the desired amount. You then adjust your flash power until your flash meter tells you to use the f stop at which you are already set for the ambient exposure.

Another method: Meter the flash first, and set your camera's aperture according to the meter. Then meter the ambient light. See what shutter speed is recommended for the aperture at which your camera is set. Set the shutter speed to be faster that this, to darken the ambient light the desired amount.

The first method gives finer control, and also makes the desired exposure much more attainable with focal plane shutter cameras. This is because as the first step, a fixed shutter speed is set; one that will synchronize with electronic flash. Then, an f stop is chosen to match. Then, flash power is finely tailored to fit the f stop.

The second method is faster, but gives more course control (unless shooting with a camera that can set in 1/3 shutter speeds), and works best with leaf shutter cameras. This is because with a leaf shutter, you have the entire range of available shutter speeds to use for controlling ambient exposure. The ability to use shutter speed to control ambient exposure will never be nixed above a certain shutter speed, like it is with a focal plane shutter.

but could you be cutting out some of the flash's bandwidth if you use too high of a shutter speed? what i mean is, using a too-high of a shutter speed cut out some of the strobes colorband?

i remember dean collins talking about this, using a fast shutter speed can keep some of your strobe's colorband from being recorded.

not sure if this is still the same with current strobes, or just the 1980's ones that are in the Dean Collins videos from the 80s

bibowj · Aug 9, 2009

Thanks 2F , thats exactly the kind of info I was interested in!

I realize that light is light for either medium. THe only reason I asked was that with DSLR, I can do test shots w/ my camera running into Lightroom on site to make sure all is perfect. I really wanted to know how to do this almost mathematically and still get the same results. Thanks!

John Koehrer · Aug 9, 2009

DanielStone said:
but could you be cutting out some of the flash's bandwidth if you use too high of a shutter speed? what i mean is, using a too-high of a shutter speed cut out some of the strobes colorband?

i remember dean collins talking about this, using a fast shutter speed can keep some of your strobe's colorband from being recorded.

not sure if this is still the same with current strobes, or just the 1980's ones that are in the Dean Collins videos from the 80s

The flash will have completely discharged before your shutter begins to close.

2F/2F · Aug 9, 2009

DanielStone said:
but could you be cutting out some of the flash's bandwidth if you use too high of a shutter speed? what i mean is, using a too-high of a shutter speed cut out some of the strobes colorband?

i remember dean collins talking about this, using a fast shutter speed can keep some of your strobe's colorband from being recorded.

not sure if this is still the same with current strobes, or just the 1980's ones that are in the Dean Collins videos from the 80s

I don't know for sure, because I don't know exactly how electronic flashes work. It could be that the electronic flash has to "ramp up" a bit to get to its intended color temperature of light, however, this would happen very quickly nonetheless. AFAIK the duration of electronic flash never has its edges clipped by a leaf shutter speed (unless the synch timing is off, of course).

Perhaps Mr. Collins was talking about class M flashbulbs, which do have their duration clipped off more and more the faster your leaf shutter fires above the fastest speed that captures the full duration (usually '30 or so). It certainly seems feasible that with flashbulbs, there could be a variation in color temperature during the long duration of the flash such that one of the top shutter speeds clipping off the edge of the duration might slightly change the color balance.

I can't imagine such a "modern high-end gear" head ever giving commercial instruction in flash bulbs, however. Maybe it happened, though. Light is light, but when he was "doing his thing", flashbulbs were definitely not "the thing". The videos of his that I have been forced to watch view like advertisements for Sinar-Bron, Hasselblad, and Lightform, and I can't imagine him pulling out some flashbulbs in one of them. Narrator: "Collins loads a Sylvania Press #25B flash bulb into his 3-cell Heiland-Research flashgun mounted on such-and-such light stand, yadda yadda yadda..."

As you can tell, I never got to see him speak in person, which I am sure I would have loved, and was stuck with the cheesy videos being shoved down my throat in school.

Perhaps he was simply saying that the duration of electronic flash has an inherent effect on the color temperature that the flash emits. I don't know if this is true or not...just thinking of things that you might have heard.

Sirius Glass · Aug 9, 2009

DanielStone said:
but could you be cutting out some of the flash's bandwidth if you use too high of a shutter speed? what i mean is, using a too-high of a shutter speed cut out some of the strobes colorband?

i remember dean collins talking about this, using a fast shutter speed can keep some of your strobe's colorband from being recorded.

not sure if this is still the same with current strobes, or just the 1980's ones that are in the Dean Collins videos from the 80s

With a focal plane shutter, you are limited to the fastest speed that the shutter is completely open.

With a leaf shutter, the stobe duration is much slower than the fastest shutter speed.

Is the question of color band does not apply.

Steve

Lee L · Aug 9, 2009

Sirius Glass said:
With a leaf shutter, the stobe duration is much slower than the fastest shutter speed.

Steve

I'm sure Steve will catch this, but the correct statement is that the strobe duration is much shorter than the fastest leaf shutter speed, and it's timed to occur during the maximum opening of the shutter.

I can't think of any reason for Collins to warn about color this way unless he's talking about extremely short duration flash (1/10,000 second and likely shorter) where high intensity reciprocity failure (HIRF) might cause a color shift in some films. Studio flashes don't have durations short enough to cause HIRF, as they're pumping a lot of power through the tube and the common tubes need more time to handle that much total output. It would be silly to design a standard studio flash head that causes HIRF anyway.

Lee

PeteZ8 · Aug 9, 2009

You need to check the strobe duration of your flashes. Most modern lights (monolight and pack lights) are between 1/750 for the lower end models with higher end gear usually up in the 1/1000-1/1500 of a second range. As long as you keep your shutter speed below the flash duration for your lights you shouldn't have any issues with clipping anything, including color band.

Of course, to get the most efficiency out of your lights you'll want to knock down the ambient as much as you can with shutter speed, then resort to the aperature ring.

PeteZ8 · Aug 9, 2009

Sirius Glass said:
With a focal plane shutter, you are limited to the fastest speed that the shutter is completely open.

Steve

Not entirely true, at least not all the time.

A lot depends on the shot and what you are trying to light.

For example, if you have a subject that fills 70% of the frame and the rest is sky, you can probably bump the shutter speed a stop or so and still not clip anything since the strobe is not lighting the sky. If your shutter clips the bottom of the frame, shoot it upside down so the clipped part of the image is on the top section which is only ambient light anyway.

If you're using a curtain shutter (like a K1000) that moves sideways, obviously the affected portion will be on one side or the other, rather than the top or bottom with a blade shutter.

BetterSense · Aug 9, 2009

I'm sure Steve will catch this, but the correct statement is that the strobe duration is much shorter than the fastest leaf shutter speed, and it's timed to occur during the maximum opening of the shutter.

Test this before you rely on it. I have a leaf shutter that does NOT give the same exposure at high speeds as it does at low speeds. The flash sync must be off.

Lee L · Aug 10, 2009

BetterSense said:
Test this before you rely on it. I have a leaf shutter that does NOT give the same exposure at high speeds as it does at low speeds. The flash sync must be off.

You may also have experienced this with a thyristor controlled studio flash. Thyristors can only handle limited current, so the total flash output is stretched over a longer period at levels that the thyristor can handle. But this drives output from the flash into the durations that a leaf shutter can cut off, sometimes as slow as 1/50 second. Shoe mount units don't put out enough power to cause this problem, and so work well with thyristors at very short durations.

In any case, I never ran into the problem you describe with leaf shutters in decent working condition in MF or LF lenses using decent studio strobes in a dozen or so studios where I worked. Perhaps cheap monolights would be different.

Lee

Alan Johnson · Aug 10, 2009

Using a focal plane shutter at 1/60 sec for 100 ISO film on a dull day the sky reading gives me f16.Stopping down two stops to darken the sky gives f32.
Thus even a powerful strobe with a guide number of 64 meters only gives a working distance of 2 meters.Options are somewhat limited when I have no leaf shutter lens for my Mamiya,but certain shots are still possible with the camera close to the subject.

BetterSense · Aug 10, 2009

You may also have experienced this with a thyristor controlled studio flash. Thyristors can only handle limited current, so the total flash output is stretched over a longer period at levels that the thyristor can handle. But this drives output from the flash into the durations that a leaf shutter can cut off, sometimes as slow as 1/50 second. Shoe mount units don't put out enough power to cause this problem, and so work well with thyristors at very short durations.

In this case it was a Nikon SB-28 on a flash bracket. Puzzling, but I still have the negatives.

Sirius Glass · Aug 10, 2009

BetterSense said:
Test this before you rely on it. I have a leaf shutter that does NOT give the same exposure at high speeds as it does at low speeds. The flash sync must be off.

Yes, my fingers were not typing what the brain was thinking. It should have been that the strobe was much faster than the shutter speed.

Steve

JohnRichard · Sep 5, 2009

This is the most amazing thing I have ever SEEN! It's like he glued chromes onto my monitor. I need this technique in my life.
Let me see if I got this correct: Meter the ambient light and set up the camera for what the meter gives. Lets say f16 at 1/125. Then I want to meter my strobe until it gives me 1/250 or so at the f-stop I have selected? Someone correct me if I got it wrong. I'm gonna go practice!

Blowing out the sun

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