Studio Strobe and slower shutter speeds ( 1/4 - 1/60 )

[1erCru]

If someone is using only strobes in a room with little or no ambient light what is the advantage of using slower shutter speeds for still life. I've read a leaf shutter adapts to most shutter speeds up to a certain point , but isnt a flash of light the same speed no matter what?

I've read of many people shooting largeformat and using strobes and stating that they rarely shoot above 1/60 of a second. Ifs there's no ambient or LED's being used in conjunction with the strobe then what's the point ?

If the modeling lamp doesn't dim after firing I can see the film soaking in a bit of the photons from that but in a completely dark environment wouldn't exposing the film to complete darkness simply increase contrast and grain?

[Bob Salomon]

A leaf shutter syncs electronic flash at all shutter speeds. A focal plane or a guillitene syncs electronic flash at any speed where the entire image area is fully uncovered by the shutter.

[1erCru]

Yeah , I understand that. How exactly would one benefit from using a slower shutter speed with a leaf shutter. I understand the math behind a faster shutter but with slower speeds I don't see how the strobe interacts / responds to the leaf shutter in a beneficial way ( if there is no ambient )

[Mark Sawyer]

A longer shutter speed will capture all the light from longer-burning flashes, like some flash bulbs which may emit light for 1/8 of as second or so, and may take a fraction of a second to ignite. Electronic strobes tend to be so fast (around 1/200 to 1/2000) that any shutter speed works.

[Bob Salomon]

Yeah , I understand that. How exactly would one benefit from using a slower shutter speed with a leaf shutter. I understand the math behind a faster shutter but with slower speeds I don't see how the strobe interacts / responds to the leaf shutter in a beneficial way ( if there is no ambient )

You use your shutter speeds to control the ratio between the ambient light and the output from the flash. Use a very fast shutter speed and you will have a very dark or black background. As you use slower shutter speeds the background exposure will become lighter.

[Pere Casals]

If someone is using only strobes in a room with little or no ambient light what is the advantage of using slower shutter speeds for still life. I've read a leaf shutter adapts to most shutter speeds up to a certain point , but isnt a flash of light the same speed no matter what?

I've read of many people shooting largeformat and using strobes and stating that they rarely shoot above 1/60 of a second. Ifs there's no ambient or LED's being used in conjunction with the strobe then what's the point ?

If the modeling lamp doesn't dim after firing I can see the film soaking in a bit of the photons from that but in a completely dark environment wouldn't exposing the film to complete darkness simply increase contrast and grain?


In general Pros use modeling light to adjust key vs fill power balance, to preview light modification (softbox, etc) and fall-off (The Inverse-Square Law), and then they usually shot with the strobe to have a not shaked image.


The impact of the modeling lamp it can be calculated.

For example if modeling lamp has 300w, if you use it at full power and you shot 1/8s then you get the illuminator throwing 300/8 w·s, this is 37.5 w·s, same impact than if the modeling lamp had 37w and exposure was 1s.

It the flash bulb (that is also fired at same time) has a 500 w·s power and your setting is 1/2 of the full power then you throw 250 w·s, so 7 times more exposure than the modeling light example. Both modeling and strobe are shot at same distance to the subject (and same modificator), so their relative power it is also the relative effect in exposure.


For still live you can shot with the modeling light or with the flash, ro with both... but the modeling lamp is tungsten (today it can be a daylight type LED source), while the flash has daylight color temperature, this is important for BW because the ISO you rate the film may vary depending on tungsten or daylight.

Single reason to expose with modeling light is that you use tungsten equilibrated color film (today is scarce, Vision 3 500T ) and you don't want to use a corrective filter for flash/whitebalance. Another reason is that your subject is completely static and you don't need the strobe.


In general, modeling light is to "model", it is not to shot. If modeling light plays a big share in the exposure (flash at 1/64 and modeling set at maximum) you lose the freezing action of the flash, With strobe you don't have much blur because camera shake or subject motion.

...so with modeling light you model to your desire, then you can measure modeling illumination for key an fill illuminators, also you can set the relative power for the key and fill strobes. Another way is spot metering fill and key illuminations and then you use a flashimeter to in the same spots and orientation to adjust the strobes.

Fortunately today we are in the digital era, and we can use a DSLR as a perfect flashmeter/exposimeter for the view camera.

[chassis]

For a room with little or no ambient light, there is no advantage in using a slower shutter speed for still life. To satisfy oneself of this, try two tests.

With a flash meter (I use a Sekonic L-758DR), trigger the strobe and the meter will tell you the % of exposure from the strobe. Second test: with any light meter, take an ambient reading at your desired aperture, without strobe. If the room has little or no ambient light, the flash meter with strobe reading should be 100% and the ambient reading without strobe should indicate underexposed.

In both of the tests, modelling light will be accounted for, and the tests can be done with and without modelling light to see the contribution (if any).

[Two23]

I shoot outdoors at night, mostly, for the past ~11 years. If there is no ambient light, in effect the duration of the flash becomes the "shutter." For what you are describing, shutter speed really isn't a factor. If the room is totally dark (no ambient at all or 5 stops less than the flash output,) you can even use the "open" flash technique. For this you open the shutter on bulb, pop the flash, and then close the shutter. If you don't have a moving subject, it will be perfectly sharp. If there is some contributing ambient light, then remember that shutter controls ambient, aperture controls flash.


Kent in SD

[LabRat]

Flash duration goes something like this;

There is an initial very fast rise to a peak of brightness (where the flash duration is measured), but there is a period afterward where there is some remaining illumination (I think the term is holdover), that is less bright, but still there (this is the part that your eye actually sees)... On some strobes, the color temp can change during holdover, but the bright peak dominates the film image...

If you shot a shutter on M sync, you would miss the peak, but still might see some dim image on your film, with screwy color maybe (this is that region)... But if your exposure was long enough, there might remains of the holdover region that could possibly leave a slight cast to your color film under a combination of very low power/long exposure/wide f stop/fast film conditions (with some strobes), but usually can't be detected, but a test is always a good thing before important shooting when using these combinations...

Flash units that have longer duration peaks are ones to watch out for longer holdover...

Steve K

[Mark Sawyer]

You can also divert power from the plasma conduits to the deflector dish to power the flash unit warp coils. That way the tachyon burst prolongs the shutter's relative exposure time continuum...

Oh, wait, that's Star Trek. Never mind...

[DrTang]

zero point

[Ari]

You can also divert power from the plasma conduits to the deflector dish to power the flash unit warp coils. That way the tachyon burst prolongs the shutter's relative exposure time continuum...

Oh, wait, that's Star Trek. Never mind...

Stuff and nonsense; you cannot change the laws of physics.
Everyone knows that emitting a tachyon pulse will cause the shutter to be rendered inoperable for at least 4 hours, during which time you can easily disarm your average Romulan.

[Kevin J. Kolosky]

Back when I was doing a lot of weddings I used this technique almost every week. For altar photos of the wedding party prior to the service I would meter my lights (photogenic) for proper exposure for the wedding party. I would set that exposure into my camera. Then I would meter the background and make adjustments. As you know, the inverse square law states that light falls off with the square of the distance. since I didn't want to carry a lot of strobes to also light the background, and since the strobes I was using were aimed at the people, the light from those strobes fell off considerably before hitting the background. the only way to correct for that was to drag the shutter, which I did most of the time. So sometimes in very dark churches I was shooting at f 8 at 1/2 second or even f8 at 1 second in order to get some decent detail in the background. Of course I would have to tell everyone to hold very still during these long (for people shots anyway) exposures. And since light is additive, the low incident light didn't have much effect on the flash exposure on the people.

So yes, dragging the shutter is a very good technique for balancing between strobe and incident light.

[Tracy Storer]

I shoot in dim studios with flash often, many of my lenses are in Ilex #5 shutters (max speed 1/50) or barrel lenses used with Packard shutters (max speed depends on size, but generally not faster than 1/30 or so )
When using strobes at full power, the flash duration is longer than at lower power settings. It's unlikely you'll have any trouble at 1/500, and less likely slower than that. (rational is that most flash durations are in the 4th decimal place, less than 1/1000.
1/500 = 0.002 Seconds, or "two Thousanths")

[Bob Salomon]

I shoot in dim studios with flash often, many of my lenses are in Ilex #5 shutters (max speed 1/50) or barrel lenses used with Packard shutters (max speed depends on size, but generally not faster than 1/30 or so )
When using strobes at full power, the flash duration is longer than at lower power settings. It's unlikely you'll have any trouble at 1/500, and less likely slower than that. (rational is that most flash durations are in the 4th decimal place, less than 1/1000.
1/500 = 0.002 Seconds, or "two Thousanths")
Some studio strobes, for the past 30 odd years, have constant flash duration at all outputs. Some others allow you to vary the duration regardless of power setting.