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Thread: Calibrating Modern Flash & Flash Bulbs & Zone Focus 4X5

  1. #11

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    Re: Calibrating Modern Flash & Flash Bulbs & Zone Focus 4X5

    Quote Originally Posted by Tin Can View Post
    Found this guy testing

    Quality of light comparison - Electronic Flash vs M3 flash bulb vs AG-1 flash cube

    Quality of light comparison - Electronic Flash vs M3 flash bulb vs AG-1 flash cube
    That guy cracks me up with the plant growing out of his head.

    His hypothesis on "quality of light" is flawed, light is light--there's no difference.

    The actual difference enters in due to exposure time... a strobe exposes over 1/5000 of a second or faster, whereas a flash bulb exposes over about 1/50th of a second.

    This is evident in old sports photos taken with flashbulbs, there's just enough motion blur to describe the action:

    Click image for larger version. 

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    compare that with a photo in the film/strobe era, which looks completely static:

    Click image for larger version. 

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    Of course these days modern digital can shoot high enough iso's that you can shoot 1/100th of a second indoors without using a flash, so the scenarios where flashbulbs would be warranted are slim, but in very dark situations with fast action, I can still see a use.

  2. #12

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    Re: Calibrating Modern Flash & Flash Bulbs & Zone Focus 4X5

    Quote Originally Posted by djphoto View Post
    That guy cracks me up with the plant growing out of his head.

    His hypothesis on "quality of light" is flawed, light is light--there's no difference.

    The actual difference enters in due to exposure time... a strobe exposes over 1/5000 of a second or faster, whereas a flash bulb exposes over about 1/50th of a second.

    This is evident in old sports photos taken with flashbulbs, there's just enough motion blur to describe the action:

    Click image for larger version. 

Name:	sugar-vs-lamotta.jpg 
Views:	21 
Size:	40.2 KB 
ID:	227051

    compare that with a photo in the film/strobe era, which looks completely static:

    Click image for larger version. 

Name:	300px-TysonThomas.jpg 
Views:	16 
Size:	20.5 KB 
ID:	227052

    Of course these days modern digital can shoot high enough iso's that you can shoot 1/100th of a second indoors without using a flash, so the scenarios where flashbulbs would be warranted are slim, but in very dark situations with fast action, I can still see a use.
    Depends on the strobe. Rollei E250, E1250 and E5000 had constant flash duration of 1/250.

  3. #13

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    Re: Calibrating Modern Flash & Flash Bulbs & Zone Focus 4X5

    Weegee, and other freelance and news photographers of his time simplified things.
    The lens was set at a preferred aperture. The camera was focused at the hyperfocal distance, or a preferred shorter distance. The shutter was set at a speed which allowed it to be fully open when the flash was at it's peak,
    When they went to make a photograph they estimated the distance and the aperture provided enough depth of field to provide adequate sharpness. Their development was standardized, but in unusual circumstances special well known techniques were utilized.
    All exposures were made with flashbulbs, day and night and exposure was based entirely on the output of the bulb.
    Weegee had several cameras in the trunk of his car ready to go. Each was set for a particular type of picture - closeup, to about 10 or 12 feet, mid-distance up to about 20 feet, etc.
    It worked well. I worked closely with a freelancer who gave me my first Speed, and taught me the "tricks".
    I didn't own a meter for the first 10+ years i used this camera. Never an unprintable negative as long as I followed all the rules.

  4. #14

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    Re: Calibrating Modern Flash & Flash Bulbs & Zone Focus 4X5

    Previous discussion about flash bulbs..
    https://www.largeformatphotography.i...ith-flashbulbs

    More about the differences between small compact electronic flash units -vs- vast production flash bulbs than one being "better" than the other.

    If tasked with strobe/flash lighting a room used in this example, easy initial would be to use a BIG umbrella with a strobe/flash head that has enough power to produce the needed lens aperture for the image goals (larger the sheet of film, more strobe/flash power will be needed). Know both the vast production flash bulb and compact electronic flash unit are effectively a very small light source with not a lot of light output for the image area to be covered. This will result in hard/specular/ un-even lighting of the area being imaged. Using a basic umbrella with a proper strobe/flash head will produce an effectively larger light source with better light uniformity over a larger area. Other light modifiers from BIG soft box, wide angle reflector with BIG diffusion sheet in front, BIG reflector and more. All depends on how the lighting wants to be used to achieve a specific emotional expression in this area to be illuminated.

    Color rendition is a factor that can be controlled and predicted by proper testing.
    Clear flash bulbs have a typical color temperature of 4000 degrees Kelvin. Blue flash bulbs have a color temperature closer to 5000 degrees Kelvin due to the blue coating which works as a color correction filter, brings up the color temperature while giving up or trading off light output from the flash bulb.


    All this has been previously done decades ago, being discovered by those new to all this.
    Bernice




    Quote Originally Posted by Tin Can View Post
    Found this guy testing

    Quality of light comparison - Electronic Flash vs M3 flash bulb vs AG-1 flash cube

    Quality of light comparison - Electronic Flash vs M3 flash bulb vs AG-1 flash cube

  5. #15

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    Re: Calibrating Modern Flash & Flash Bulbs & Zone Focus 4X5

    Flash bulbs have a "burn-up" time or time required for ignition of the steel wool inside the oxygen filled glass envelop... typical "M" bulb takes about 20milliseconds to reach peak light output. This is also why vintage shutters have a "M" sync setting, to compensate for the time required for the flash bulb to reach peak light output, about 80milliseconds overall.
    https://filmphotographyproject.com/flash-bulbs-lowdown/

    Electronic strobe/flash units typically use a Xeon flash tube. They also have a time required to reach peak light output, except that time is often in micro seconds or less, far faster than a flash bulb (why "X" sync on shutters, and no image recorded if electronic flash/strobe is used with the shutter set at "M" sync) and their light output duration is typically shorter than a flash bulb. The xeon flash tube light output duration varies depending on tube design, power output, power source and..

    One of the more common higher power flash tube configurations is circular (S type for Elinchrom) with ends like this
    Click image for larger version. 

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    This flash tube has a single arc path producing light when triggered. Time required to reach peak light output and for the light form the arc to die off is related to the total length of the single arc path. If 4000watt/seconds of light output is produced by these single arc path flash tubes, the flash duration would be about 1/350 to 1/500 second. Not ideal for "stop" action images, trading off LOTs of light output.
    Click image for larger version. 

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    Another type of flash tube has two arc light paths. This is achieved by placing the arc electrodes 180 degree apart in a circular tube (A type for Elinchrom).
    With two paths for the arc to produce light, the effective distance between electrodes is reduced resulting in less time require for the arcs to produce peak light output and less time for the arcs to die out or dissipate.
    Click image for larger version. 

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    If 4000watt/seconds of light output is produced by these single arc path flash tubes, the flash duration would be about 1/900 to 1/1000 second. Better for "stop action" images than the single arc light path flash tubes.


    Then we get into lower power flash/strobe units that can produce shorter flash durations which is ideal for stop action images. Lowest power using an type A Elinchrom flash tube/head results in a flash duration of 1/4000 second, can work good for stop action images.
    Click image for larger version. 

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    This flash duration spec has become a marketing hook in the current offering of electronic flash units. Note this flash duration for the Profoto 10 (near bottom of this page), it's flash duration grows as light output power grows. There is no escape from the physics involved with Xeon flash tubes.
    http://www.peterbelanger.com/blog/20...1i1qswq0anj89h

    At 2.4watt/seconds in their "freeze mode" flash duration is 1/80000 second which is not that different than compact portable flash/strobe units with similar light output. Once up to 2400watt/seconds flash duration is 1/1000 second in "freeze mode" which is much the same as using the A type flash tube/head for Elinchrom (at 4000watt/seconds, twice or 1 f-stop more than the Profoto 10). This is the current marketing game being played out in the current electronic flash/strobe struggle to sell their wares.

    Current short duration electronic flash/strobe units achieve short flash duration by a combination of shorten arc light path tubes and a high power solid state device (IGBT, thyristor, SCR or similar) to cut off the power going into the flash tube. This with a combination of altering the regulated voltage at the flash capacitors and time allowed of energy flow into the flash tube is how modern electronic flash units achieve 7 or more f-stops of light output range gaining the ability to reduce flash duration time.


    Bernice






    Quote Originally Posted by djphoto View Post
    That guy cracks me up with the plant growing out of his head.

    His hypothesis on "quality of light" is flawed, light is light--there's no difference.

    The actual difference enters in due to exposure time... a strobe exposes over 1/5000 of a second or faster, whereas a flash bulb exposes over about 1/50th of a second.

    This is evident in old sports photos taken with flashbulbs, there's just enough motion blur to describe the action:

    Click image for larger version. 

Name:	sugar-vs-lamotta.jpg 
Views:	21 
Size:	40.2 KB 
ID:	227051

    compare that with a photo in the film/strobe era, which looks completely static:

    Click image for larger version. 

Name:	300px-TysonThomas.jpg 
Views:	16 
Size:	20.5 KB 
ID:	227052

    Of course these days modern digital can shoot high enough iso's that you can shoot 1/100th of a second indoors without using a flash, so the scenarios where flashbulbs would be warranted are slim, but in very dark situations with fast action, I can still see a use.

  6. #16

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    Re: Calibrating Modern Flash & Flash Bulbs & Zone Focus 4X5

    Circa 1968 Singer Company acquired GPE/ Graflex, introduced the Strobomatic 500 portable electronic flash unit with switchable power outputs of 50/100/200 watt/seconds.
    https://ghq.graflex.org/GHQ-13-4.pdf

    This was revolutionary back in the days when flash bulbs were the accepted and common way of achieving this kind of light output for 4x5 press camera images to weddings. Not long after this the Norman 200B (and others) replaced the Strobomatic 500 to become one of the most common portable electronic flash units made.
    http://normanlights.com/manuals/200Bmanual.pdf

    https://www.largeformatphotography.i...ht=norman+200b



    The game with these 50/100/200 watt second portable electronic flash units was their effective guide number of 160 at ASA (ISO) 100 or f16 at 10 feet using a standard reflector on the flash head. In real world image making, set the lens at f16, estimate the camera to subject distance to be about 10 ft, then "fire" to record the image. The 10 ft subject to camera chart looked like this:

    f16 at 200watt/second.

    f11 at 100watt/second.

    f8 at 50watt/second.

    This was the basic chart. At f16 images became "zone" focused as f16 allowed estimated focusing applying "apparent" focus from the small aperture used (f16) to compensate or make up sort of for critical focusing of camera to subject.



    Bernice

  7. #17

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    Re: Calibrating Modern Flash & Flash Bulbs & Zone Focus 4X5

    Quote Originally Posted by Bernice Loui View Post
    Flash bulbs have a "burn-up" time or time required for ignition of the steel wool inside the oxygen filled glass envelop... typical "M" bulb takes about 20milliseconds to reach peak light output. This is also why vintage shutters have a "M" sync setting, to compensate for the time required for the flash bulb to reach peak light output, about 80milliseconds overall.
    https://filmphotographyproject.com/flash-bulbs-lowdown/

    Electronic strobe/flash units typically use a Xeon flash tube. They also have a time required to reach peak light output, except that time is often in micro seconds or less, far faster than a flash bulb (why "X" sync on shutters, and no image recorded if electronic flash/strobe is used with the shutter set at "M" sync) and their light output duration is typically shorter than a flash bulb. The xeon flash tube light output duration varies depending on tube design, power output, power source and..

    One of the more common higher power flash tube configurations is circular (S type for Elinchrom) with ends like this
    Click image for larger version. 

Name:	Elinchrom S flash tube noted.jpg 
Views:	7 
Size:	51.8 KB 
ID:	227084

    This flash tube has a single arc path producing light when triggered. Time required to reach peak light output and for the light form the arc to die off is related to the total length of the single arc path. If 4000watt/seconds of light output is produced by these single arc path flash tubes, the flash duration would be about 1/350 to 1/500 second. Not ideal for "stop" action images, trading off LOTs of light output.
    Click image for larger version. 

Name:	Elinchrom A_S flash durartion.jpg 
Views:	6 
Size:	57.1 KB 
ID:	227085

    Another type of flash tube has two arc light paths. This is achieved by placing the arc electrodes 180 degree apart in a circular tube (A type for Elinchrom).
    With two paths for the arc to produce light, the effective distance between electrodes is reduced resulting in less time require for the arcs to produce peak light output and less time for the arcs to die out or dissipate.
    Click image for larger version. 

Name:	Elinchrom A flash tube notes.jpg 
Views:	6 
Size:	44.0 KB 
ID:	227086

    If 4000watt/seconds of light output is produced by these single arc path flash tubes, the flash duration would be about 1/900 to 1/1000 second. Better for "stop action" images than the single arc light path flash tubes.


    Then we get into lower power flash/strobe units that can produce shorter flash durations which is ideal for stop action images. Lowest power using an type A Elinchrom flash tube/head results in a flash duration of 1/4000 second, can work good for stop action images.
    Click image for larger version. 

Name:	Elinchrom Ranger flash head duration.jpg 
Views:	6 
Size:	74.5 KB 
ID:	227087


    This flash duration spec has become a marketing hook in the current offering of electronic flash units. Note this flash duration for the Profoto 10 (near bottom of this page), it's flash duration grows as light output power grows. There is no escape from the physics involved with Xeon flash tubes.
    http://www.peterbelanger.com/blog/20...1i1qswq0anj89h

    At 2.4watt/seconds in their "freeze mode" flash duration is 1/80000 second which is not that different than compact portable flash/strobe units with similar light output. Once up to 2400watt/seconds flash duration is 1/1000 second in "freeze mode" which is much the same as using the A type flash tube/head for Elinchrom (at 4000watt/seconds, twice or 1 f-stop more than the Profoto 10). This is the current marketing game being played out in the current electronic flash/strobe struggle to sell their wares.

    Current short duration electronic flash/strobe units achieve short flash duration by a combination of shorten arc light path tubes and a high power solid state device (IGBT, thyristor, SCR or similar) to cut off the power going into the flash tube. This with a combination of altering the regulated voltage at the flash capacitors and time allowed of energy flow into the flash tube is how modern electronic flash units achieve 7 or more f-stops of light output range gaining the ability to reduce flash duration time.


    Bernice
    Bernice, isn’t it about time that you learned that watt seconds is not output, can not be converted directly to a guide number or actual output?
    Watt seconds is another major “marketing ploy”!

  8. #18

  9. #19

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    Re: Calibrating Modern Flash & Flash Bulbs & Zone Focus 4X5

    Yes indeediee Bob, watt/seconds is a relative measure. Same game with Guide Numbers.

    This is why using an accurate flash meter is absolutely essential. Once light modifiers are applied (which is nearly 100% of the time for proper strobe/flash heads) all this watt/seconds, Guide numbers babble become extremely meaningless.

    Fact is, two Elinchrom 404 (4000 watt/second) power packs into a X8000 flash head (8000 watt/seconds total) will produce a LOT more light output than any battery powered compact flash unit.. or why watt/second become a relative power output metric.


    Bernice


    Quote Originally Posted by Bob Salomon View Post
    Bernice, isn’t it about time that you learned that watt seconds is not output, can not be converted directly to a guide number or actual output?
    Watt seconds is another major “marketing ploy”!

  10. #20

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    Re: Calibrating Modern Flash & Flash Bulbs & Zone Focus 4X5

    Profoto B2 – Freeze Mode

    Power 2.0 (1ws) – 8000K
    Power 3.0 (2ws) – 8100K
    Power 4.0 (3.9ws) – 7750K
    Power 5.0 (7.8ws) – 7150K
    Power 6.0 (15.6ws) – 6750K
    Power 7.0 (31.25ws) – 6600K
    Power 8.0 (62.5ws) – 6500K
    Power 9.0 (125ws) – 6350K
    Power 10.0 (250ws) – 6150K


    Paul C Buff Einstein E640 – Action Mode

    Power 2.0 (2.5ws) – 7250K
    Power 3.0 (5ws) – 7000K
    Power 4.0 (10ws) – 7050K
    Power 5.0 (20ws) – 6850K
    Power 6.0 (40ws) – 6700K
    Power 7.0 (80ws) – 6350K
    Power 8.0 (160ws) – 6050K
    Power 9.0 (320ws) – 5900K
    Power 10.0 (640ws) – 5600K

    ~Physics of how Xeon flash tubes work applies here, color temperature shift due to the method Profoto is using to gain shorter flash duration.
    Shift up in color temperature increases the effective "blueish" rendering for the color recording method referenced to 5000 degrees Kelvin.

    Part of why those Elinchrom strobe/flash units remain, they have good color temperature control over their light output range. This is true for Broncolor and similar often forgotten electronic strobe/flash units from the past. Back then good color temperature control over the power range was essential and mandatory as color transparency film was sensitive to shifts in lighting color temperature. It was why owning a Minolta color meter IIIF and a stack of cc filters for both lens and lighting with gray card film batch testing was essential for color control in color transparencies. Today it seems, Fotoshop and similar color adjuster sliders have become the solution to this problem.. which is not quite the same as getting the color proper, accurate-precise on film from the get go.


    Bernice




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