Technique: leaf Shutter and strobe

[Bernice Loui]

This works depending on the intensity of the ambient light -vs- power of the flash bulb. If one were to use one of those "nuke" Edison base flash bulbs at short distance (10 ft_ish), ambient light intensity is not likely going to be a problem .... Ever. Do this same measurement with a Kodak Flash cube, ambient light -vs- shutter time and built light intensity will be a problem at ... 10ft.

Really a question of bulb burn up time -vs- film speed -vs- shutter open time. Possible to make an ambient light measurement for a given film speed and shutter speed, then figure in this exposure to the amount of light that would be added by the flash bulb.



Bernice

Correct, and to add: Concerning the flash meter with flashbulbs. It is my understanding that if one uses cord mode with correct set shutter speed (or longer) in meter, then a correct flashbulb reading will be made. The cord by-passes sensing of the initiation of flash because bulbs have a long, gentle rise-time which w/o cord mode cannot reliably trigger the meter.

Thank you for any correction you may offer, Bernice.

I am suddenly tempted to try cord-mode with my 1.7 second duration bulbs.

[Bernice Loui]

OK..... why, explain?


Bernice

Also, do not point the meter at the strobe(s) as suggested in post #7. Point the dome at the camera from the subject position.

[Peter De Smidt]

Because the final reading needs to take into account the key light and the fill light, i.e. the fill light will likely add some light to the areas already illuminate by the key light.

[Jac@stafford.net]

This works depending on the intensity of the ambient light -vs- power of the flash bulb.

With bulbs in cord mode, the meter does not depend upon the flash to initiate metering. Ambient light is just added to the measure for the duration of the meter's setting of shutter speed.

[Bob Salomon]

Because the final reading needs to take into account the key light and the fill light, i.e. the fill light will likely add some light to the areas already illuminate by the key light.

Are you talking about classic Rembrandt Portrait Lighting or something else?

Remember, expose for the shadows, the fill light is what the exposure is based on, the key light determines the ratio, which is normally 3:1.

That means you base your exposure solely on the fill light. Then you turn your fill light off and measure the key light so it is 2 stops more then the fill light.

[Leigh]

That means you base your exposure solely on the fill light. Then you turn your fill light off and measure the key light so it is 2 stops more then the fill light.

Hi Bob,

Does that work regardless of whether or not the key and fill overlap?

- Leigh

[Bob Salomon]

Hi Bob,

Does that work regardless of whether or not the key and fill overlap?

- Leigh

You are exposing for the shadow so the key light is not on while metering the fill. When the key light is on it won’t make a difference in the exposure as long as the key is not replacing the fill light on the subject.

[Duolab123]

Shutter speed make a big difference with strobe. Shutter speed is how you balance ambient lighting to the strobe. Want a very dark background? Use a fast shutter speed. Want detail in the background? Use slower shutter speeds.

Sure for balancing ambient and strobe. So does color temperature, and reciprocity failure with traditional films. I was thinking we were talking studio lights etc. Thought we were talking how much light from flash, getting to the film, varied with changes in leaf shutter speeds.

If the OP wants to know about fill flash that's a topic onto itself.

[Duolab123]

Correct, and to add: Concerning the flash meter with flashbulbs. It is my understanding that if one uses cord mode with correct set shutter speed (or longer) in meter, then a correct flashbulb reading will be made. The cord by-passes sensing of the initiation of flash because bulbs have a long, gentle rise-time which w/o cord mode cannot reliably trigger the meter.

Thank you for any correction you may offer, Bernice.

I am suddenly tempted to try cord-mode with my 1.7 second duration bulbs.

I had a garden shed with a huge stockpile of flashbulbs, Edison socket, #25 etc. I got rid of them, I was afraid I would have an accident some night and think the Russians had nuked us . At that time we were in the country. If that shed had got hit by lightning, between the propane, gasoline, flashbulbs and old ammunition it would have been picked up by the "Space Command" :-)

[Pieter]

Incident light meters are designed to measure the light hitting the subject as seen from the camera position, taking in all the lights, fill cards and reflectors. I often used a strong, raking backlight or feather the strobe, the subject just catching the edge of the light and that would give me bad readings if the meter were pointed directly at the source.

OK..... why, explain?


Bernice